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avatar_WacKEDmaN

464 Resurrection - with only mainboard!

Started by WacKEDmaN, 18:35, 09 December 20

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eto

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.

WacKEDmaN

#51
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 :(

Audronic

Ok 
Last thoughts :-
Change 
IC115 75LS244
And /Or
IC114 74LS373

Keep Safe

Ray
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

WacKEDmaN

#53
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....
You cannot view this attachment.
 

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.....
You cannot view this attachment.

....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...


Audronic

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
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Audronic

#55
Do you have an other 40009 Rom to try ?

Can you temporarily add to the New Mother board a reset switch ?

Ray
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

WacKEDmaN

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....
You cannot view this attachment.


 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...

Audronic

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

Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

WacKEDmaN

Quote from: Audronic on 13:22, 12 May 22
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



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?


WacKEDmaN

#59
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!
You cannot view this attachment.

Audronic

#60
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
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Audronic

Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

WacKEDmaN

#62
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!!

WacKEDmaN

#63
..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!...

WacKEDmaN

;D
..and still going...
You cannot view this attachment.

WacKEDmaN

#65
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?!
You cannot view this attachment.

..and i also cleaned up my workbench..  ;D
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Bryce

I thought you had a 40010 GA on your board? It doesn't get hot enough to ever need a heatsink.

Bryce.

Devlin

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
CPC464 & CPC6128 + USIfAC II + Revaldinho 512k(universal cpld ver) - Schneider CRT TV
Administrator of Amstrad Discord : https://discord.gg/ksWvApv

WacKEDmaN

#68
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!)

Bryce

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.

TotO

#70
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.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

WacKEDmaN

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..

WacKEDmaN

#72
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)


WacKEDmaN

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..

WacKEDmaN

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!
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