so ive got the original 464 board completely populated now...
i only have the board.. no monitor, no keyboard, no tapedeck.. im gonna add my own digital versions with overpowered arduino and/or esp32
i will use this thread to document my progress and ask a few questions (so i dont blow it up!)
i need some clarification on the power jack... i cant find the correct information, is it "centre negative" or "centre positive"...
ive done a continuity test...between the side pin of the barrel jack socket (onboard)... and both the AY-3 (pin 3) and Z80As (pin 11) 5v pins... and they seem connected...
but everything ive read is saying the 5v jack is centre positive.. even tho im seeing different on the board...
can anyone clarify it for me please?... (or should i just give up now! LOL)
next no so much a question but my next steps...... i have a SCART to RF modulator.. with female scart in...
i found this... http://www.cpcwiki.eu/imgs/c/c1/Cpc_to_scart.png (http://www.cpcwiki.eu/imgs/c/c1/Cpc_to_scart.png)
i will be wiring the 464 board directly to the scart pins on the RF board (in reverse! female din to female scart)...
heres the current look....
(https://i.imgur.com/PjV5WlP.jpg)
Center is positive for 5V and GND is outside... Just check the ground continuity with other connectors.
You can test the 74LSxx IC where the bottom left pin = GND and the top right pin = VCC. (not the RAM)
thanks ToTO, ill wire up the scart and kick it in the guts...
hopefully theres not other issues on the board...i hope i dont have to break out the sillyscope!
it does seem a bit strange the side pin on the barrel jack socket is connected to 5v positive on the main chips.. and the one coming from the centre is neg... yet it seems swapped from the actual 5v plug... all the other barrel jack sockets ive played with are outside to side pin, and then centre to centre... this seems swapped :/
i guess theres some inverse logic going on here...
tested side pin on the barrel jack socket to bottom RIGHT pin of the 74LS132p and they are indeed ground... (i looked up the datasheet!)
im confuse! ..but ill work it out! (ahh im workin from the top of the board!.. flip it..and yes bottom left is gnd ..top right is pos!)
Quote from: WacKEDmaN on 18:54, 09 December 20
thanks ToTO, ill wire up the scart and kick it in the guts...
hopefully theres not other issues on the board...i hope i dont have to break out the sillyscope!
it does seem a bit strange the side pin on the barrel jack socket is connected to 5v positive on the main chips.. and the one coming from the centre is neg... yet it seems swapped from the actual 5v plug... all the other barrel jack sockets ive played with are outside to side pin, and then centre to centre... this seems swapped :/
i guess theres some inverse logic going on here...
tested side pin on the barrel jack socket to bottom RIGHT pin of the 74LS132p and they are indeed ground... (i looked up the datasheet!)
im confuse! ..but ill work it out! (ahh im workin from the top of the board!.. flip it..and yes bottom left is gnd ..top right is pos!)
As far as I know, the plug is positive on centre pole unless you have a very rare version of a 464. :D
How do you check continuity from jack center to the IC pins ?
5V should no go straight from the plug to the ICs. You have to do a short on the tape connector, where the power switch is connected.
oh yeah! that probably explains why im having issues!... ive got the board sitting on the bloody silver side of the cardboard shield!
now im not getting continuity on the centre to the 5v in on the 74LS chips even with the switch connector bridged :/
(i was forgetting the switch! thanks for the heads up Gerald!)
...it looks like i know enough...just to be dangerous! LOL
hooked up scart..and powered up the board..
..and nothing.. seems to draw about 0.9Amp and there seems to be activity on the z80 buses.. (checked with oscilloscope..)
...need to checked voltages ..seems to be 4.3v on everything..
CRTC chip (HD6845SP)seems to be getting warm after a few minuites.. (ram very slightly).. is it known to get warm to hot? (its not burning hot!)
seems to be working..i just cant get a picture ::)
..i might invest in a cga/ega to vga board...the scart to RF modulator is horrible, i plugged wii into it to make sure it works..
..ok thats ordered.. should be here by the end of the year if im lucky! :)
so the EGA/CGA to VGA board arrived today...
wired it up (soldered to the pins on bottom of cpc board)... this board and pinout.. https://www.octoate.de/articles/connect-cpc-to-vga-display/ (https://www.octoate.de/articles/connect-cpc-to-vga-display/)
but still no picture...
Question: does the cpc "need" anything else connected on boot? like does it look for the tape drive or keyboard? im guessing not
i cant test the the board is working (just no pic) with no speaker or keyboard! (cant hit esc/delete to beep!)... i suppose i could hook up an amp and speaker to the headphone jack.. but bit hard to make a keyboard from an arduino without the display showing!
next step is to replace the Z80... i tryed it on a bread board and it was doing weird things on the bus.. (would stop increasing the address bus after a few cycles just doing nops..should continue increasing right?)
be a few more weeks before ill get my hands on them tho with xmas and new years
The CPC Mainboard will run with nothing attached accept the power cord. You would need some test equipment to know whether it's running or not, so it easier to have it connected to a display at least.
Bryce.
thanks Bryce
i do have an oscilloscope.. (guess i need a logic analyser)..
not sure what i should be looking at!.. i am seeing activity on both the data and address buses on all the main chips..and the logic chips seem to be all be working...
but like i said i think the z80 maybe bad..so im going to replace that first..
...another month before i get to move on!..unless someone has some ideas for me! :P
What are you getting on pins 39 and 40 of the CRTC?
Bryce.
[screwup]... this is pin 40 of the CRTC (pin 39 looks the same) with just the power connected, no jumper between pin1 and 3 on the tape connector (power switch)..power supply says no current!
when i do jumper it, it remains the same... just triggering more often ... and showing about 90mA current usage on the power supply...[/screwup]
ermagherd im dumb!.. i scoped the clock pin!..and the power supply was too close inducing the ripple onto the signal.... SMH...told ya im dangerous! LOL
... ok next attempt!... this is the real pin 40..
it seems its triggering vsync every half second or so...that doesnt sound right.. should be with every frame drawn right?..
10ms timebase..
(https://i.imgur.com/vjZFzEx.png)
here it is at 500ms timebase..
(https://i.imgur.com/cDeaK6r.png)
for pin 39 - hsync...its looking much better..
200us timebase!
(https://i.imgur.com/o1cvzOh.png)
it also seems the CRTC is the hottest IC after having it running for about an hour..its much warmer than the 40007 gate array...
..im gonna order a CRTC chip and some z80s... cant hurt to have spares!..
also grabbed a 6pin din today..so ill rewire the EGA to VGA board to make things a little nicer..
edit.. so after some reading i find this..
Quote"The standard monitors on the Amstrad (GT6x, CTM64x, CM14 or even TV) have a 50Hz Vertical refresh rate (meaning that a VSync pulse must appear every ~20ms, 19968μs exactly) and a 15625Hz Horizontal refresh rate (an HSync pulse every 64μs). Of course they can usually tolerate some slight variations of these timings but each monitor has it's own limitations."
it seems the vsync timings are a bit off on my board?!
If you probed properly and that's the output of pin 40, then the CRTC has an issue. The signal levels are too low too. But just to be 100% sure: What scope are you using?
Bryce.
cheap hantek 6022be...
thanks Bryce.. CRTC will be socketed and replaced..aswell as the z80 replaced for good measure!
so got the new CTRC and Z80s today..
...removed the old CTRC IC..and put a socket in..
fired it up...
and same..no sign of video.....altho all the chips seem to be getting hotter now....ill have to check on oscilloscope later...
...i think im in over my head :doh:
so ive had a bit of a look around the CRTC with a continuity tester....
seems i killed some vias ripping the old chip out and puttin the new socket in... now i gotta rip the socket out (and possably destroy more vias) and wire the bastard up!
...im thinking i might make a "floating" chip! (wires outta the board to the socket) coz fixing it with the socket in place is gonna be a PITA!
i wonder if it would be cheaper (labour wise), easier, and nicer in the long run, if i was to redesign the board to make it smaller.....
...or...
should i just stop now and send this to someone i know can fix it!? would make a nice vid for a youtube channel!:P
(llopis im looking at you!)
YAY! i finally got some output!
i pushed down hard on the CRTC... and it booted!.. i guess i need to touch up the solder joints!
but that said... it look like there is ram issues...
i get either a gray screen with blue border, or corrupt colored pixels on screen...
im correct thinking this is the ram right?
Yup, RAM problem.
Bryce.
thanks Bryce..
...more waiting for parts...
..im back!.. with the fix to my issues! ;D
IMG_20220414_045541.jpg
i should have it going in a few hours..then i have to make a keyboard for it! :P
powered it up.. no boot... its pulling 700mA... which seems a bit low? (usually around 800mA on boot right)..
checked chips and they all seem to be getting about 4.3v... time to setup the oscilloscope again....
Maybe check the diodes orientation.
You should be getting 5v not 4.3, and that 0.7v difference is the same as the usual diode voltage drop.
tried the diode..no luck..(band at the top of the board right?)
i may have the transistors installed wrong.. i used the new ones that came with the board..
my shitty scope is showing 8mhz out of the xtal...(again a new 16mhz)... and it looks horrible.. it seems to be very low voltage wise too..
the clock on the z80 and gate array seems to be just under 4mhz... but its not square.. (dont think its my shitty oscilloscope)...theres no activity on the z80 bus either..
i may remove the original transistors and try them...
...i suck at desoldering/removing components.. ...the whole reason i got this board! LOL
edit:
https://pdf1.alldatasheet.com/datasheet-pdf/view/2827/MOTOROLA/2N2369.html .. hard to tell which leg is which..
it seems i may have got the collector and base around the wrong way.....check and double checked..and rechecked..and its installed right!..
The clock signal will never be a perfect square as shown in textbooks. It will always be rounded and the lower the bandwidth of your scope, the worse the signal will look. However, it doesn't need to be a perfect square, all that matters is that it's there and passes a certain threshold on each cycle. The 4.3V is a bigger issue. You need to find out where the other 0.7V is being lost.
Bryce.
thanks Bryce...
it use to be 4.3v on original board aswell..... do you think i could possibly have a bad logic chip somewhere? (i havent got a tester)
..i guess i could pull one chip at a time and see when the voltage goes up!
my scope is still the hantek6022BE...only 24Mhz bandwidth but should be plenty... the clock signal out of the gate array looks nothing like it does in Noels youtube vid... its the same at the nand gates and at the crystal (just lower voltage. i even changed that back to the original!)
...ive changed Ram, CTRC, and z80.. so really theres only the logic, AY, PIO, and ROM that could be bad..
How are you powering the board?
powering the board with a small CV/CC power supply i use for all my micros n what not, 5v exactly at the barrel jack on the board..has voltage and current draw displays so i can see whats being used..
heres the clock on the scope.. (with "phosphor" on to sorta help..)..i see no squares!
..at pin 12 of the quad nand...
Screenshot 2022-04-16 044958.png
and here is leg of R141 (out of the opamp..to z80)..its just lower on pin 39 on the gate array..
Screenshot 2022-04-16 044009.png
the CRTC pin 21 is generating a nice square-ish wave..
...im going to replace the LS153s, the 244, 373, 32 and the 00, later today if i can get over to the shop..i cant get the others locally unfortunately..
How much current can your power supply give?
I think around 2 amps should be good but you'll need more if you add expansions.
Quote from: robcfg on 23:23, 15 April 22How much current can your power supply give?
I think around 2 amps should be good but you'll need more if you add expansions.
3Amp... 5 with better cooling!
i noticed all the main chips getting warm, gate array, z80, crtc, pio..are all a bit warm..
so i changed the 4 LS153s, the 244, 273, 373, and the 00..
the last 3 LS chips will need to be ordered from somewhere...
...and same result...(i think my scope cant keep up with the clock..CRTC is puting out nice square waves.)
no activity on the bus..(low this time)
im really stumped.....
i guess i could order a new AY, and PIO...and new CRTC for good measure..
...maybe a rom burner aswell...
seems i cant get an ay, ppi, or crtc in the country...SMH...good old parts shortage...
what should i be checking for next...? ..could it be ram/rom?..if i pull all them, it should just nop right? so i should see activity on the address bus...
or should i be checking something else on the gate array?
should i pull the rom and try to read it with an arduino?
maybe i should pull TR2 and replace it with the original?..(altho that shouldnt stop bus activity)
not sure where to go next.. some help would be appreciated..
ordered the LS32,LS132 and LS145...should be here in a coupla weeks knowing auspost!
ive got a funny feeling its LS132 or LS32.. LS132 would make sense being part of the reset circuit..
so you had a board a couple of years ago, now you have a different board but that doesn't work either, tbh not sure what it say.
Quote from: tjohnson on 00:45, 19 April 22so you had a board a couple of years ago, now you have a different board but that doesn't work either, tbh not sure what it say.
yup...its that bad!..ive been at this about 18months now...
..old board i purchased online cheap.. missing the gate array.. sourced one from Tot0 here.. no boot..
i was playing around with it and pushed down hard on the CRTC and got a screen..but looked like bad ram..never has it booted again!...
tryed replacing CRTC..killed the board..damaged tracks and ripped out almost every via on the CRTC :/
...so waited till these new boards where available..soldered it up.. looked good.. put chips in..nothin.. tried replacing most of the logic, the ram is also new..crtc is new..
could only be the ROM..the 8522, the AY-3, a bad CRTC..or hate to say it..bad gate array..
..i dont have a rom burner, or any rom boards like dandanator etc.. so im flying blind!... i do have sillyscope.. but its crap! wont read the 16mhz clock, 4 and 1mhz is fine..
other than replacing the logic i havent replaced yet.. im stumped where to go next...
What are you trying to achieve? Maybe you can send the board to Bryce to diagnose and get working. I'm assuming the board is actual known working i.e. not a development board where there could be faults. Tbh it would have been easier to find a working machine i would think rather than trying to build a new board.
Quote from: tjohnson on 08:29, 19 April 22What are you trying to achieve? Maybe you can send the board to Bryce to diagnose and get working. I'm assuming the board is actual known working i.e. not a development board where there could be faults. Tbh it would have been easier to find a working machine i would think rather than trying to build a new board.
just trying to get a working cpc!..
this is the board ive after it was tested and faults found and fixed..
https://www.tindie.com/products/bobsbits/amstrad-cpc464-replica-pcb/
and ..im in australia..so im not really fond of sending it out of the country...i waited a month for the new board to arrive..
so i bumped up the voltage on my power supply to 5.6v... chips now getting 4.9v.. but still no boot :(
24MHz is definitely not enough bandwidth to measure a 16MHz square wave. I've a post here which will explain why: https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/understanding-retro-electronics/msg144677/#msg144677
Bryce.
yes Bryce..that was what i thought!... Nyquist says you need atleast double the bandwidth of the frequency youre trying to measure.... the clocks out of the gate array look fine so im going to assume the 16mhz clock is fine too...
got the last of the logic chips today.... and still nothing...
not even a black screen signal.....
so..thats gotta be gate array or CRTC right?!
ill order another CRTC... but...if its gate array..im guessing im screwed until the chip is reengineered....
i did notice the 3 new logic chips increased the current by almost 100mA... it pulled 1A on first boot with the new chips but dropped to 970mA shortly after...
I know that sensation... You have a computer that cost cheaply and you want it work and you begin buy buy and buy pieces because nothing work and at finish you spend 10x more money that another cost on eBay or similar.
I'n your case the 464 are the more cheaply.. Maybe os better search another and then you can swap ics?.
But well,you have here a gate array spares.
https://www.icompplus.com/es/circuitos-integrados/12619/40010
https://www.icompplus.com/es/circuitos-integrados/32243/40007
I have not buy there... But they are in my city. I can made a order there and pickup it in person.
Quote from: dragon on 10:48, 26 April 22I know that sensation... You have a computer that cost cheaply and you want it work and you begin buy buy and buy pieces because nothing work and at finish you spend 10x more money that another cost on eBay or similar.
I'n your case the 464 are the more cheaply.. Maybe os better search another and then you can swap ics?.
But well,you have here a gate array spares.
https://www.icompplus.com/es/circuitos-integrados/12619/40010
https://www.icompplus.com/es/circuitos-integrados/32243/40007
I have not buy there... But they are in my city. I can made a order there and pickup it in person.
yup its a bit like that!... but i havent really spent all that much trying to get it working (thats if you dont count the new black board!)...all the logic only cost about $20.. got the gate array from user here for like 20$ with postage..CRTC was coupla $... the original board was purchased very cheap as it was missing the gate array (and obviously had other issues!)
thanks for the links ... i'll check them out....
i finally got in contact with a local who has a complete CPC collection....so i maybe able to swap some chips over between his boards and mine to test...
yay! finally some signs of life!
got a hold of a lower rom board with diagnostics... plug it in..fire up the cpc.. hit the reset button... and i get a screen!..albeit corrupted!
IMG_20220511_164024.jpg
this is with the original ram chips... ill drop my new ones in and see what happens....
its really looking like the rom is the whole issue with my board....
Throw the left hand switch to the other position
With the the Computer turned off
Power up and tell us what happened
Keep Safe
Ray
Quote from: Audronic on 07:48, 11 May 22Throw the left hand switch to the other position
With the the Computer turned off
Power up and tell us what happened
Keep Safe
Ray
...still with the original ram...
IMG_20220511_165636.jpg
i guess i need to start working on my ps2 keyboard through arduino if i wanna test some more! (or atleast workout which pins to hit to fake a keypress!)
EDIT: i tryed rebooting Noels rom and now i just get corruption cant read anything... interesting...
well this is a bit strange....
i dropped the "new" ram chips in and just got corruption....
i removed 1 ram chip (top left)... and now i get the ram tester screen....
its saying chip 3 is bad... even tho, what im presuming is chip 0 is missing!
what is the layout for the chips on the ram tester??
IMG_20220511_171438.jpg
Can you send us a Photo of the Motherboard
Noels diag photo said " 128K ram" ????
Ray
Edited Removed NO FDC
464 Ram Location
Bit
0 IC 120
1 IC119
2 IC 118
3 IC 117
4 IC 121
5 IC 122
6 IC 123
7 IC 124
-================-
121. 117
122. 118
123 119
124 120
-================-
Ray
yes i thought the 128kB was a bit strange aswell...theres a pic of the board on page 1...
thanks for the ram location.. i ended up working it out after testing one chip through all the sockets..
i havent been able to get back to that diag screen (Noels)..
i keep getting corruption.... UNLESS i remove chip 3 (top left ram chip)...then i get the ram tester screen...
ive tryed that chip in other slots and it is green... no matter what ram chip i use in slot 3 just causes corruption (they are all showing green in other slots)
i tried taking one ram chip and running it through all slots on its own... some slots would make the colors change (eg purple instead of green)..one would show a few green lines in the correct area but none of the numbers or other lines show...
....thats probably CRTC correct?
edit: heres a pic of the tester with no ram... is that dotted line between 0 and 1 supposed to be there?!
IMG_20220511_180835.jpg
edit2: heres the current setup....
IMG_20220511_183038.jpg
Quote from: WacKEDmaN on 08:52, 11 May 22i keep getting corruption.... UNLESS i remove chip 3 (top left ram chip)...then i get the ram tester screen...
ive tryed that chip in other slots and it is green... no matter what ram chip i use in slot 3 just causes corruption (they are all showing green in other slots)
Ok I would check the "Chip 3 Soldering for Perhaps shorts to ? " and have a good look at Pins 2 and 14
Good luck
Ray
Quote from: WacKEDmaN on 08:52, 11 May 22i keep getting corruption.... UNLESS i remove chip 3 (top left ram chip)...then i get the ram tester screen...
ive tryed that chip in other slots and it is green... no matter what ram chip i use in slot 3 just causes corruption (they are all showing green in other slots)
so most likely not the ram chips. and since all ram chips fail in that socket, it might be the socket. or the lines to the socket.
did you check for shorts/continuity for all pins on that socket?
edit: sorry, just recognised Audronic already said that.
checked all the ram pins for shorts... seems fine...
pin 2 on each socket has continuity to an individual pin on the CRTC...
pin 14 on each socket has continuity to an individual pin on the gate array... (ill admit i didnt check to see they where going to the correct pins..but it 'should' be ok)
all ram pins except 2 and 14 are connected across all sockets....
...so im guessing...bad CRTC..or ....(plz no!)..gate array :(
Ok
Last thoughts :-
Change
IC115 75LS244
And /Or
IC114 74LS373
Keep Safe
Ray
Quote from: Audronic on 08:51, 12 May 22Ok
Last thoughts :-
Change
IC115 75LS244
And /Or
IC114 74LS373
Keep Safe
Ray
:o :o :o :o :o :o :o :o :o :o :o
holy crap!..
big THANK YOU to everyone who had some input!
swapped out the brand new 244 for the original one....
IMG_20220512_182812.jpg
then i switched it off...flipped the on/off switch on the lower rom board... power back up and.... nothing... i hit the reset button and then got this.....
IMG_20220512_183051.jpg
....it seems there maybe still an issue tho... if i remove the lower rom board, and power up the CPC it does not boot (not even black screen/sync).... it only seems to boot the original rom when i hit the reset button with the rom board switch set to off...
edit: seems i need to hit the reset on the lower rom board every boot....its not booting on its own...
Ok Thats good progress
Perhaps the Rom on the motherboard is unwell
? does the Other Diag work (Geralds) Left switch in the other position
Nearly there
Keep Safe
Ray
Do you have an other 40009 Rom to try ?
Can you temporarily add to the New Mother board a reset switch ?
Ray
no i dont have another ROM to try as yet... a local friend has a 1.1 ROM for me..just need to get my hands on it...
yes Geralds diag loads and shows this....
IMG_20220512_202010.jpg
i jumpered the keyboard connector with a wire to hit some keys to load up some tests...(on Noels)
"CANT ACCESS SYSTEM LOWER ROM" on the ROM test...
Quote from: WacKEDmaN on 11:25, 12 May 22i jumpered the keyboard connector with a wire to hit some keys to load up some tests...(on Noels)
"CANT ACCESS SYSTEM LOWER ROM" on the ROM test...
Ok This is normal thats what mine does its not a Problem with the motherboard
I have used a 1.1 Rom that works OK
If you are stuck I can send you a 40009 Revision 2 (Rays version)
That I use with the USIFAc II
Keep Safe
Ray
Quote from: Audronic on 13:22, 12 May 22Quote from: WacKEDmaN on 11:25, 12 May 22i jumpered the keyboard connector with a wire to hit some keys to load up some tests...(on Noels)
"CANT ACCESS SYSTEM LOWER ROM" on the ROM test...
Ok This is normal thats what mine does its not a Problem with the motherboard
I have used a 1.1 Rom that works OK
If you are stuck I can send you a 40009 Revision 2 (Rays version)
That I use with the USIFAc II
Keep Safe
Ray
thank you Ray.. i should be good for the 1.1 ROM in the next couple of days...but will keep you in mind...
reguarding reset button pins...
just jumper !BUSRESET to gnd right?... or do i want !RESET?
ok... jumpered pins 2 and 40 on the edge connector without the lower rom board connected.. and it booted....
i also changed the the new 74LS132 for the original as its part of the reset circuit....no luck..
could the diode around the wrong ways (or bad) be causing it not to trigger the reset? (possibly even the capacitor?)
EDIT: working on the big screen too!
IMG_20220513_005639.jpg
The Reset Button (Momentary)
Reset Button - CPCWiki
https://www.cpcwiki.eu/index.php/Reset_Button
? Which Diode - Capacitor ?
If you are referring to the Power up reset circuit ?
In Next reply
? are you able to Boot without the Lower rom Board ?
If not then press the (New) Reset button and let go
Keep Safe
Ray
Reset Circuit
Ray
Quote from: Audronic on 00:10, 13 May 22The Reset Button (Momentary)
Reset Button - CPCWiki
https://www.cpcwiki.eu/index.php/Reset_Button
? are you able to Boot without the Lower rom Board ?
If not then press the (New) Reset button and let go
Keep Safe
Ray
yes i found that page after asking the question!..
i removed the lower rom board... powered up the cpc (no boot)...jumpered pins 2 and 40 (/BUSRESET to gnd) on the edge connector for a moment and it boots...
easier to just leave the lower rom board connected and use its reset button than jumpering or wireing up a dedicated reset button...
i can get away with using it atm....but it would be nice to have the power on reset circuit working......
ive been scanning over the reset circuit..and im thinking the diode (there is only one! and the electrolytic cap next to it) is installed incorrectly or its bad! i will try a new one soon..(replaced the 74LS132 with the original with same no boot on power-on results)
might have to break out the scope again and see what happening on the reset lines and LS132
edit: another reason im thinking the diode is the voltage drop on the chips...
ive got my CC/CV power supply turned up to 5.7V to get 4.8v on the chips.. if i go any lower, the CRTC starts acting up and the screen bounces..
or...could it be...(wait for it!) what im using for a power switch... a cheap ass dupont cable!.. that has hardly any wire inside!..maybe it cant supply enough current...i thought i felt it getting a little warm too!!
thats first test!!
..fixed!... my dumb ass had the diode around the wrong way :picard2: :picard:
the voltages seem a little low...i dropped CC/CV psu to 5.1v, and im reading 4.5v on the logic chips.. and noticed it rebooted itself after a few mins.. so i bumped up the psu to 5.25v and now im seein a more healthy 4.7v at the logic chips..
the gate array sure does get toasty without a heatsink... i gotta get one on it asap..ive only got a square one thats gonna hang over.. will get something better down the track..
now to sort out my keyboard implementation, so i can at least get some basic happening!..
i think i might have to grab a USIFAc II that thing looks really sweet!...
;D
..and still going...
IMG_20220514_080824.jpg
my arduino mega to cpc keyboard attempt failed!...
ordered an attiny2313..should be here next week..already have a LS138.. will make my own board and mount it on the bottom of the cpc board so it cant be seen/looks neater..i have the cpc board up on feet so there should be enough clearance..
also found the perfect heatsink for the gate array, on an old dead boost/buck converter!
i also changed the links so the boot screen reads "Amstrad" instead of "AWA" (my original CPC was AWA, but i toasted the PPI soldering up a joystick while it was plugged in and running (i was young and dumb!..oh wait im still dumb! LOL), when i got it back from repair the manufacturer had changed to Amstrad)
i was going through my collection of junk and found the only thing left of my original CPC system from back in the day....
the 3 meter long printer cable!.. with edge connector to centronics connector! (parents said that cable almost cost more than the dot matrix printer they got me aswell)...anyone want it?!
IMG_20220519_021522.jpg
..and i also cleaned up my workbench.. ;D
IMG_20220517_100044.jpg
I thought you had a 40010 GA on your board? It doesn't get hot enough to ever need a heatsink.
Bryce.
Quote from: Bryce on 08:59, 19 May 22I thought you had a 40010 GA on your board? It doesn't get hot enough to ever need a heatsink.
Bryce.
Looking back through the pictures, it is a 40007, unless the part has since been replaced
yes its 40007...as this is a 270100 board (1983) with only the 40007 slot..
it was getting veryyy toasty!.. so hot i could hardly keep my finger on it for too long...the heatsink now gets quite warm... but its doing its thing wicking the heat away from the chips core..
my original z80 (84) gets very hot aswell... swapped it with one from the 90s and its much cooler... i have a small heatsink on the CRTC aswell as it was quite warm too (neither as much as the gate array!)
Quote from: WacKEDmaN on 21:00, 19 May 22yes its 40007...as this is a 270100 board (1983) with only the 40007 slot..
it was getting veryyy toasty!.. so hot i could hardly keep my finger on it for too long...the heatsink now gets quite warm... but its doing its thing wicking the heat away from the chips core..
my original z80 (84) gets very hot aswell... swapped it with one from the 90s and its much cooler... i have a small heatsink on the CRTC aswell as it was quite warm too (neither as much as the gate array!)
Strange. Why did someone clone the older design, rather than cloning the improved 40010 design?
Bryce.
Quote from: Bryce on 08:00, 20 May 22Strange. Why did someone clone the older design, rather than cloning the improved 40010 design?
May be because, since the "covid confinement", a lot of peoples started to be interrested to reuse their old 1980/1990 micro-computer, without thinking that many things was known and done between 2000 and 2020 to keep them alive and attractive.
Quote from: Bryce on 08:00, 20 May 22Strange. Why did someone clone the older design, rather than cloning the improved 40010 design?
Bryce.
i thought the same too...but im glad it was done... iirc it was just a project to see if it could be done, and there is a 6128 version is currently being worked on..
seems i still have some issues with the 74LS244. (IC115)..
sometimes it wont boot.. if i push on the chip into the socket it will boot....or sometimes it shows up like memory corruption.. it reboots itself at random times aswell, with me no where near it...
ive tried resoldering the pins...but had the same issue...
...im guessing the solder hasnt flowed through the hole to make nice contact with the top side of the board...i may have to replace the socket (maybe with machined pins)
i seem to have sorted the 74LS244 issue, just by lifting the chip slightly from the socket... if i push it all the way in i get the reboots/corruption.. its a little strange..but works!
i also did some more work on my ps2 arduino to cpc keyboard.. i got one key working (just testing).. but i sometimes get other characters (from another row that isnt even connected!).. so im guessing my implementation is too slow... i may try writing directly to the arduinos port registers, should speed things up a ton...but really im just screwing around until i get the attiny2313 to do the conversion..
struggling to build up the ps2 adapter... dunno why ...but its stressing me out hard!
took me hours to workout just how to program the attiny2313 with an arduino...its supposed to be straight forward and simple (ive done it with many other chips).. but i kept getting errors... i "think" i have it programmed now... just have to finish soldering up the board...
..i "think" these are the right pins!
IMG_20220525_151643.jpg
Quote from: WacKEDmaN on 06:18, 25 May 22struggling to build up the ps2 adapter... dunno why ...but its stressing me out hard
Why directly hacking the PCB circuits pins instead of using the keyboard connector to build an adapter?
Quote from: TotO on 06:30, 25 May 22Quote from: WacKEDmaN on 06:18, 25 May 22struggling to build up the ps2 adapter... dunno why ...but its stressing me out hard
Why directly hacking the PCB circuits pins instead of using the keyboard connector to build an adapter?
good question!.. i was originally using the keyboard connector with arduino mega..but my code sucks and it was too slow..i was getting multiple keys or keys in different rows at times
so im doing Geralds PS2 adapter (just without a premade board)... the code is completely setup to use pins from the chips directly and not the keyboard connector pins. i guess i could use the keyboard connector pins that connect to the AY-3.. but the code bypasses IC101(LS145 decoder) and also uses IOWR/CS and A0/A1 from the PPI to know when the keyboard is being read
on third thought...
im going to build it up on a breadboard first... might save me some stress to get the board right!..and will allow me to test the pin outs in the schematic are correct (there seems to be some disagreement about that)
this is the schematic im working from...
PS2CPC_Standalone_sch.png
Yes, it mainly use PC0-PC3 (A, B, C, D) form the PPI and X0-X7 from the AY.
And it require a "chip select" signal when the PPI PortC is written.
/CS = (/IOWR OR A11) with A8=1 and A9=0
so i think ive got the PS2 adapter hooked up properly.. the Num lock led is lit...
but.. most the keys do nothing!.. some of the function keys pump out a bunch of characters... up and right arrow aswell.. and a few of the keys on the num keys..
eg if i hit right arrow key.. ill get 2\/MNBC hit it again and ill get 2\/mnbc (switches between shifted and not shifted)
...my keyboard is US... i guess its throwing out different key codes..which are not programmed into the adapter code
IMG_20220526_170001.jpg
.....i just spotted something i missed.... the pull up resistors for the ps2 clk and data!..and smoothing caps...SMH
EDIT: so ive attached them ...and now its worse!.. num led doesnt turn off.. and its ALWAYS sending keys to the CPC!.. just constant stream of characters!
IMG_20220526_170047.jpg
As far as I know, PS/2 keyboards also just have a matrix and send a key code based on that matrix, not caring about what version it is. International versions just have different keycaps and send the same key code, if the position of the key on the keyboard is the same.
If you want to map a US layout to the CPC layout, you have to translate this in your code.
yeah.. i thought as much...
this "solution" is really stressing me out.. i dont like it!
im considering hooking the arduino mega back to the keyboard connector and learning how to code the interrupts and port bit flipping (i was using digitalRead() and digitalWrite() but they seem too slow)
..resoldered everything.. and now its working perfect... :D ;D :D ;D :D
Stoked!.. now to wait on some cash to get a USIFAC II so i can load some stuff...
IMG_20220602_015717.jpg IMG_20220602_015750.jpg
so now ive got keyboard working.. its on to the next project...(while i wait for cash and USIFAC II)
i need a way of loading tapes/CDTs without the tape deck...
looking at the schematic, i see that the signal from the tape head is going through 2 op amps and a tranny..im thinking about using an ESP32s audio out capabilities..i guess i will need to make up an amplifier circuit to boost the signal enough for the cpc to see...
....i have some questions tho...
cant this be done purely digitally?.. i mean just feed a digital signal straight into the connector on the 464 board (near the power switch)
does anyone have a scope handy, to show me what the signal going out of the tape deck into the main board looks like please...(scope at the data out/in pins on the mainboard)
That's exactly what those two "op-amps" are doing. Taking the analogue signals from the tape/CDT and converting them into a digital signal. Of course loading can be done fully digitally, it's called loading from a disk, but if you want to read CDT's then you are starting with an analogue signal so the conversion has to happen somewhere.
Bryce.
Check out this video: https://www.youtube.com/watch?v=-cacZqQf4Go
It shows, how to add an audio-in to the 464, that works with different sources like TZXduino or an Ipad.
One thing I was also wondering while watching this and its follow-up video is, if it's possible to feed the TZXduino data directly into the PPI. Noel is doing that with the BUSY pin of the printer port to create a speed loader. I guess that should also work with the normal data-in port, if you disconnect the audio circuit: https://www.youtube.com/watch?v=MAIsOIwgJWA&t=1348s
thanks Bryce...
and eto.. the problem is i dont have a tapedeck/tape circuitry.. the usual method sends the signal through the op-amps before sending it to the mainboard...
but yes! i forgot all about that Printer port method...
i should be able to do the same sort of thing with an ESP32 instead of the TZXduino (i can probably use code from it tho!)
i could even connect the "play on input" pin to trigger the esp32 to start sending the cdt...(and then a web interface (over wifi) to select/upload cdts to the esp32s flash)
this project isnt really a priority, just something to work on while i wait for USIFAC II...
also just got a hold of a BASIC 1.1 ROM (Patched to show 64K instead of 128K)
IMG_20220602_182434.jpg
built up a tzxduino on mega2560 board..
hooked the output pin from the mega to the data in port on the cpc board..
set the tzxduino running and was greeted with it detecting the first block..runs great..i need to speed it up, im using default baud and its quite slow! ;D
IMG_20220603_172602.jpg
IMG_20220603_170404.jpg
and heres a vid of it loading first time.. and the current setup!
seems im still having an issue with IC115 (74LS244) :picard:
ive resoldered the socket (multiple times!)..but still having random crashes or reboots seemingly related to that IC.. eg if its pushed in too far it boots with gray screen and video corruption, ..or if i tap the IC or board it will sometimes reboot..(remember a brand new LS244 also fails in this socket!)
ive even had it reboot just from looking at it!!..i mean it will sit there fine for like an hour or so, i turn my head to look at the screen and boom reboot!! (happened a few times now!)..i know just coincidence ...but damn!
looks like i have to replace the socket, and if that doesnt work, solder the chip in directly... i dont see why the socket would be causing issues like this tho..
If you have to replace the socket perhaps try Turned sockets as it looks like you are using Double Wipe
Good luck
Ray
unfortunately i dont have any machined sockets handy..i do have a new dual wipe to go in tho..
..this board is so much easier to desolder and clean up than the old original board...
so soldered in the new socket... and the new LS244 works fine...but STILL getting reboots if i tap/move the board...
tryed reflowing the other sockets around the ls244...including memory.. it doesnt seem as bad..but its still an issue... :(
seems it cured most of the random reboots... like its been running Ikari Warriors for the last 12hrs... only seems to reboot if i bump or tap the board now...
oh nice.. i fired up javacpc to search for some games...
i found that you can convert disks to tape!...
so looks like im all set!..
ill still get a USIFAC II coz tape loading is slow..and ive gotta get up to change cdt on the txzduino
also...anyone know why Hunckback II doesnt like 664/6128 ? it just reboots half way through loading (does weird stuff on emulator too!) ..wont work the the 6128 rom installed...works fine with the 464 rom (that also includes the disk version converted to cdt which is very strange!)...its the only game ive found that has these sorts of issues..
It probably uses some firmware addresses that have changed for the 664/6128.
There is at least one cracked version that has been patched to work on all machines. You can find it on cpc-power.com.
now it runs crysis! :laugh: :laugh: :laugh:
IMG_20220605_235438.jpg
made up a crappy screen in javacpc.. saved to disk..transfered to cdt.. then loaded up on the real machine!
now with loading sound!
i think i found why the loading sound is played through the speaker... its coming back from the AY-3... the sound out (of the mainboard) provides the loading sound... i tested this by only connecting the sound out to the amplifier...
usifac ii seems to be working now..(needs ~6.5v with this board)
no tech support needed.. but thought id share my latest DIY addition..
IMG_20220722_150236.jpg
@WacKEDmaN, Awesome write up. I'm glad you were finally able to bring it to life!
I'm interested in the ps/2 keyboard mod you did. Can you link the the build you are using?
I just ordered one of the "Bob's bits" 6128 boards but don't have a case, keyboard, or drive for it so will be in a similar situation as you were. I am trying to come up with a solution before the new board arrives from UK.
These old CPC's are ultra rare in USA so there is no chance of getting any spares here. I plan on 3d printing a case with enlarged floppy bay to fit a 3.5 inch drive and retrofitting a PS/2 keyboard somehow.
Quote from: jb2590 on 21:10, 26 July 22@WacKEDmaN, Awesome write up. I'm glad you were finally able to bring it to life!
I'm interested in the ps/2 keyboard mod you did. Can you link the the build you are using?
I just ordered one of the "Bob's bits" 6128 boards but don't have a case, keyboard, or drive for it so will be in a similar situation as you were. I am trying to come up with a solution before the new board arrives from UK.
These old CPC's are ultra rare in USA so there is no chance of getting any spares here. I plan on 3d printing a case with enlarged floppy bay to fit a 3.5 inch drive and retrofitting a PS/2 keyboard somehow.
Thanks!
the ps2 adapter is here...
https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/is-there-any-recent-project-to-connect-a-pc-(ps2)-keyboard-to-the-cpc/175/
for the 6128 board, you'll need a 40010 Gate Array...which is hard to get, you might want to use the CPLD replacement..
https://github.com/codedchip/AMSGateArray
for disk drive, use get DDI-5 or USIFAC, or M4board, etc
today i hooked up the esp8266 to the gbs-8200
..the gbs worked ok out of the box, but had some vertical lines, and the characters looked a little blury...
so after hooking up gbs-c (and some playing with the settings) ive now got a perfect picture...and even got scanlines! (at various intensities)
WIN_20220728_13_55_05_Pro.jpg
thought i posted this yesterday...but must of forgot to hit the post button!
so i need a case for my CPC board and bits... was thinking about getting a clear case made up for it (but that will be costly)
...i found an old box my grandfather made for his lawn bowls made from beautiful Cedar wood...
im thinking about making some sort of "laptop" with it (it'll be tooo big for ya lap tho!)
what do yas reckon?! worthy?! (this is just a mock up to see that everything fit!..even fits the joystick and still allows it to be closed)
IMG_20220730_083139.jpg IMG_20220730_083153.jpg
They always said cedar wood helps keep the bugs away ;) That's a fine looking box, maybe have a false bottom to hide the pcb and have a nice place to set the keyboard. Recess the false bottom enough such that the display doesn't touch the keyboard when stowed.
Quote from: jb2590 on 19:24, 01 August 22They always said cedar wood helps keep the bugs away ;) That's a fine looking box, maybe have a false bottom to hide the pcb and have a nice place to set the keyboard. Recess the false bottom enough such that the display doesn't touch the keyboard when stowed.
i was thinking about putting like a shelf in at the back to hide wires.. i sort of want the board to be seen.. the black and gold is sweet!..ill sit the keyboard on that shelf... i cant really move the board anywhere as need access to the expansion port addons (more to come later).. i gotta really make up the PS2 adapter board hide it under the mainboard aswell..
i might have to take the monitor apart yet too, just to lower its profile...(it wont be able to be centred in the lid with the joystick either)
You may want to do it up like a nice storage box with form-fit cutout inserts to hold all your kit stable inside. Then when you want to use it you pull out the keyboard, joystick, and monitor, route the wires into the box to connect to the boards inside, close the lid, and set all the peripherals on top. It would definitely give it a classy old-school homebrew look and feel, also then you can see more of the finished wood instead the inside of the box. If someone see's it and starts nerding out on it, you can open the bonnet to show them all the cool bits inside.
getting there... its quite heavy with the monitor... i couldnt remove the back housing from it..so it still sticks out a little, but lets me hide the vga and power cable behind it...
gbs8200 is under the while foam.. ive gotta work somethin out there to hold the keyboard in place when its closed up (dont want it rubbing on the screen)
still needs power.. i was going to take power from the monitor.. but its probably better to run it separately...ill run power in from a 12v brick, power the gbs8200/esp8266 directly from the 12v..and also run that into a CC/CV boost/buck converter so i can set and monitor CPC voltage and power
just about done!.. usable now..
i just need to get some wood to make a shelf for the keyboard (ill probably do it at xmas when i visit my dad)
hooked up the speakers and hot glued them on!.. stuck down the gbs and esp and the boost/buck converter down.. tidied up the cables
made some power extensions for the monitor and 12v in and glued them to the hole i made on the bottom of the box, so i can unplug the power cables from the box with ease...
todays addition.... thanks to a local friend :)
keyboard and case + tape drive + power + speaker/vol
..tall keys with wired connection perfect for the black n gold 464 board...
theres a couple of broken keys, and Del key is missing, but can fix the ctrl and tab keys, the caps lock key is smashed tho..
keys are still useable via the plungers tho
..and now its all together... pity about the missing keys...i glued the ctrl key on as it had a broken plunger, and in the process of fixing the tab key.. i can use the plungers for the missing keys perfectly fine, so its a 100% working keyboard :)
i tested saving and loading from tape, its all working great...the volume pot is a little scratchy, but thats not problem...
i do need to fix the pause button tho... does anyone know how to fix it? or atleast keep it propped up?..