I think my CPC 6128's expansion port might be damaged.
I'd like to get Duke's M4 wifi board working correctly, but I fear this may be impossible.
The symptoms I am getting is the CPC system is highly unstable, crashing spectacularly within minutes (sometimes seconds) of having the CPC powered on with the M4 board connected. The system failure is different each time: scrolling garbage, system reset, keyboard input failure, clicking cassette reed switch, all manner of error messages... it's totally random each time.
I've tried to clean up the edge connector contacts as best as I can, but it's not helped at all. I don't have the equipment or budget to repair/replace PCB traces :(
The only other device I have which I can test the expansion port with is a Multiface Two. The MF2is also glitchy when connected, but more stable than when the M4 board is connected. i.e. - with the multiface connected, the CPC won't crash or reset, and I can load and run programs from disk. The problems only start after I press the MF2's stop button, but even then the glitches are minor like some garbage pixels appearing on the screen, and the system can usually recover and keep on going, but not always.
Other than cleaning up the edge connector traces, what else can I try?
@blackdalek (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2263)
I use an eraser (Rubber) as per Photo.
Please clean both the Upper and Lower contacts.
The Eraser (Rubber) is Cut down to clean the Underside contacts.
Good Luck
Ray
audronics advice is one in which many expansions need to address as these (expansion connectors) can become "dirty" or even worse corroded. The later is something in which it will eventually fail completely over time.
rpalmer
I fear my expansion port connectors may fall into the "corroded" category
Can you post some photos of the connector top and Bottom.
Thanks Ray
I use a record cleaner solution I bought on ebay to clean contacts. Put a few drops on the tip of a cotton swab and rub that hard on each individual pin. I used an eraser before but wasn't satisfied with the result. I'm using this product specifically (https://www.ebay.com.au/itm/Vinyl-Record-Cleaner-Into-The-Groove-SAMPLES-2-x-50ml-100ml-TESTER-BOTTLES-/351550470219), got myself a 50ml bottle and most of it is still unused after cleaning a dozen of game cartridges.
If the contacts are corroded you can apply a small amount of solder over the corrosion: put a blob on it then remove it with a braid. It will leave a very thin layer of lead over the faulty contact.
And if the traces are broken you will need to use wires to repair them.
[edit]
QuoteOther than cleaning up the edge connector traces, what else can I try?
Test the continuity between the CPC board and the expansion. Use a multimeter (most have that option), follow the trace of the first pin on the cpc to the nearest component, and do the same on the expansion board. test continuity between these two components. Do that for each 50 pins.
But it's very likely you just haven't cleaned them well enough.
I went with the nuclear option and soldered locking pin headers directly to the edge connectors. Also means I can easily make up new cables without having to hunt down more obsolete connectors.
@pelrun (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1106)
Do you have some Photos Please
Ray
When the edge connectors fail, it can be a very good time to upgrade to centronics :) Sadly, this means that you will have to modify the case too... but it is quite worth it, in my opinion :)
Quote from: Audronic on 23:13, 05 November 17
Do you have some Photos Please
http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/edge-adapters-(motherx4-ribbon-cable)/msg101542/#msg101542
Quote from: pelrun on 08:05, 06 November 17
http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/edge-adapters-(motherx4-ribbon-cable)/msg101542/#msg101542 (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/edge-adapters-(motherx4-ribbon-cable)/msg101542/#msg101542)
Thanks
Ray
OK. I finally got a chance to take the CPC apart again (looking after a 3 month old is time consuming lol!)
Examining it under better light, the tracks don't actually look as bad as I thought they did. Attached are some photos of the expansion port top and underside.
What do you think? They look OK to me I guess, but I'm no expert....
OK, I must be doing something wrong, because every time I try to attach a jpg I get an error...
An Error Has Occurred! Your attachment has failed security checks and cannot be uploaded. Please consult the forum administrator.
Going to try something... removed the exif and xmp data from the files...
Do you have a continuity tester?
Quote from: khaz on 16:34, 17 November 17
Do you have a continuity tester?
I have a multimeter with continuity test, yes. I'll try to test all the pins tomorrow.
Do you have a spare Z80 by chance ?
My original 464 once started to be unstable will all its extension connected and It worked fine without.
Replacing the Z80 solved the problem.
Update:
[attach=2]
I've plugged the M4 board in and performed continuity test between the 50-pin connector pins on the M4 and the solder spots between the CPU and the PCB edge. All pins showed continuity with resistance between 0.7 and 0.5 ohms.
I then tested continuity between the solder spots and the CPU leg sockets... again all contacts gave 0.7 to 0.5 ohms.
Is this good or bad?
What should I test next? Is it time to test a new Z80A? I have no spares :(
Where can I get a suitable working Z80A CPU to test with? Does anyone on the forum want to sell me one? :)
There's plenty on ebay
https://www.ebay.com/itm/1pcs-Z0840004PSC-Z0840004PSC-Z80CPU-DIP-40
Does it have to be a Z80A CPU or can it be any Z80 CPU?
An update...
After thoroughly cleaning and recoating all 50 contacts of the expansion edge connector.... I'm still experiencing flaky and unstable operation no matter what I connect to the expansion port.
So perhaps it's not my edge connectors after all?
Next I will try replacing my Z80. I have no spare to use, so I will have to order one off ebay. This could take between 10-30 days.
Does anyone in Australia have a spare Z80A they wish to sell me so I can get one faster? ;)
EDIT:
I'm starting to get pretty desperate to fix my CPC6128 expansion port problem. I'm beginning to wonder if I should just pack the main logic board into an old keyboard box and mail it to someone more technically minded and pay them to fix it for me... :-[
Is there anyone in Australia willing to examine my 6128 motherboard if I post it to them? ;) I'd pay you for your time of course.
The symptoms are: Plugging any kind of device into the expansion port gives varying and unpredictable results, and depending on the device, can make the whole CPC so unstable it crashes after a few seconds of putting the CPU under load. Anything can happen when powering on the CPC with a device connected to the expansion ranging from a few pixels of garbage, to a jumbled screen to no sign on message at all and no monitor picture. Another quirk that occurs from time to time is the keyboard gets scrambled so that the key you press does not correspond to what appears on the screen. Other times the tape relay switch might click or the disc drive may suddenly spin up.
I've tested and re-tested the continuity of the traces to the edge connector finger plates and the resistance and conductivity always seems good.
In desperation, (lacking any kind of proper electro plating kit) I went ahead and painted over every one of the 50 finger with spot of solder in the hopes that this might fix it. Continuity test results never changed - every pin on the expansion port still seemed to be working great.... but the unstable CPC problem persisted.
I've pulled the Z80 CPU and cleaned its socket out with a blast of compressed air. Reseated in and still the problem persists. I don't yet have any other CPU to test with.
I've run out of ideas of what else to try. I don't know what else I should test next. :(
Z80 Posted
Ray
Thanks Ray.
The replacement Z80 did not make any difference :(
I am still experiencing random glitches and crashes while anything is plugged into my expansion port.
Other than the contacts of the edge connector, what else can I check?
Is there some other component between the edge connector and the Z80 I should check which may be causing the problem?
I realise now that my CPC has probably had this issue since I bought it.
I bought a PACE RS232 interface many years ago which never worked and always crashed. I always assumed the RS232 was broken and resold it as not working. The only other device I have ever had connected is a Multiface 2, and although it worked most of the time, it occasionally froze or put garbage up on the screen when I pressed the red button. I just assumed that was normal for the device. Looking back now, the RS232 was probably perfectly fine and I gave it away for next to nothing thinking it was broken :(
Fast forward to 2018.... I've recently started collecting new gadgets to connect, and only now I've started to realise my CPC was at fault and not the devices I connected.
Have you measured the voltage on the PCB? Is it getting 5V?
Bryce.
Also to make sure your replating job is OK, probably it would be best to connect ie. MotherX4 to the expansion port and measure signals directly from the Z80 & GA to the male pin header on the rear of the MotherX4.
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225) My multimeter read 4.92 +V off pin 27 with nothing connected to the expansion port.
@Duke (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1624) where is the GA? I know where the Z80 is at least ;) ...and which pins on the Z80 or GA do I test etc?
Have you ever opened and cleaned the power switch? 4.92V is ok with no further load, but connecting extra hardware might pull it below the limit (4.75V is where TTL ICs will start glitching).
Bryce.
I never even knew it was possible to open the power switch. :o
It does not look easy to take apart and get back together again. Perhaps I should just solder a new switch in if it is the culprit?
Quote from: blackdalek on 08:57, 16 March 18
@Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225) My multimeter read 4.92 +V off pin 27 with nothing connected to the expansion port.
@Duke (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1624) where is the GA? I know where the Z80 is at least ;) ...and which pins on the Z80 or GA do I test etc?
Check the expansion port pinout here:
http://www.cpcwiki.eu/index.php/Connector:Expansion_port
Z80 pinout:
http://static.righto.com/images/z80/pinout.png
As for the gate array it's the 40010 chip on your motherboard, check signals ramrd and romen.
http://www.cpcwiki.eu/index.php?title=Gate_Array_and_ASIC_Pin-Outs
Quote from: blackdalek on 09:07, 16 March 18
I never even knew it was possible to open the power switch. :o
It does not look easy to take apart and get back together again. Perhaps I should just solder a new switch in if it is the culprit?
You can short the pins of the power switch at the PCB (small 2 pin header) to see if the switch is the culprit (short with jumper and then re-measure the 5V rail). There are pictures somewhere here in the forum of how to open and clean the switch if it does turn out to need cleaning.
Bryce.
I've made a new discovery...
I just spent the last half hour soldering my MotherX4 board together (I got mailed a kit by mistake :P ) to enable me to plug in more than one device at a time.
This is what I found:
M4 board in slot 1 & slot 2 empty = CPC boots OK with M4 message
M4 board in slot 1 & slot 2 Z-Mem card = CPC blank monitor. Will not boot.
Z-Mem in slot 1 & slot 2 empty = CPC boots OK
MF2 board in slot 1 and Z-Mem in slot 2 = CPC blank. No boot.
MF2 Board in slot 1 & slot 2 empty = CPC boots OK and MF2 works
M4 board in slot 2, slot 1 empty = CPC boots OK
MF2 board in slot 2, slot 1 empty CPC boots OK
So as you have probably gathered, I can run 1 board (unstable and glitchy), in any slot of the MotherX4 board.
But if I add 2 boards to any slot of the MotherX4 board, the CPC refuses to start.
Sound like a voltage issue?
Quote from: blackdalek on 11:30, 16 March 18
Sound like a voltage issue?
Yes, try to connect an external 5V PSU to the MotherX4
Quote from: Duke on 11:53, 16 March 18
Yes, try to connect an external 5V PSU to the MotherX4
Sadly, I have no 5V PSU with a connector that fits. All the PSU I could find in the house output 8V or 12V or somewhere in between.
The best I can do at this time is power the M4 board through its USB port. I have no idea if other cards on the MotherX4 board can share this USB power from the M4.
** edit: OK, I connected the M4 to USB power and put the Multiface 2 card into the MotherX4 board as well. At first the CPC did not turn on again, but after I pressed the reset M4 board button, it sprang to life and both the M4 and MF2 are working normally.
I ran a test program executing the |time rsx command on a loop. That ran stable for 5 minutes before I manually aborted it. Much longer than ever before.
I then loaded Chibi Akumas Episode 1 from the M4's SD card. Now this game I have NEVER been able to run any longer than 30 seconds before it crashed the whole CPC spectacularly. This time it ran stable and lasted through to the 4th stage without glitching or crashing. Again I had to manually terminate the program instead of having it crash the CPC.
Putting more power through to devices on my expansion port seems to at least be making the CPC run stable, so this voltage loss does indeed appear to be at the root of my CPC's problems.
I guess the next step is to follow Bryce's advice and test the power switch to see if it needs a clean (or replace).
Definitely a power problem. Either your PSU can't supply enough amps (for that setup I would advise you to use a PSU that can supply at least 3A or more), or there is too much voltage drop across things like the power switch.
Bryce.
I also have an ABBA drive swapping switch which I soldered in myself about 30 years ago. Should I also check that or would it not affect the voltage?
My PSU is currently the CTM 644 Colour monitor ;)
Found this on ebay... https://www.ebay.com.au/itm/351567502313
Does this look suitable to power the motherx4 board?
Quote from: blackdalek on 12:19, 16 March 18
At first the CPC did not turn on again, but after I pressed the reset M4 board button, it sprang to life and both the M4 and MF2 are working normally.
I have to do this everytime since i have my M4 Board, and then everything always works well...
@blackdalek (http://www.cpcwiki.eu/forum/index.php?action=profile;u=2263)
Just fold back the 4 tabs.
Disassemble carefully.
Straighten the little silver contact.
Clean all contact points with MILD abrasive, Cotton bud to clean the ones in the Body of the Switch.
Reassemble.
And away you go.
Good Luck
Ray
Quote from: Bryce on 09:00, 16 March 18
Have you ever opened and cleaned the power switch? 4.92V is ok with no further load, but connecting extra hardware might pull it below the limit (4.75V is where TTL ICs will start glitching).
Bryce.
I found a good soaking of contact cleaner followed by some switching and it was good as new without needing to open it.
I seem to be taking 1 step forward, 2 steps back.
I found a 5V 2A power supply with the correct plug size for the Motherx4 board.
It seems to work with these combinations:
Multiface 2 & M4 board = OK
Z-Mem card & M4 board = Crashes horribly
Z-Mem card & Multiface 2 board = OK
I wanted to run SymbOS 3 off the SD card in the M4, but that's not going to happen because it crashes when the Z-Mem card is in place.
SymbOS loads perfectly with the Z-Mem card removed, but is unusable because there is no free memory available to the system.
To make matters worse... I just made voltage measurements off the expansion port with the power switch shorted at the main board PCB... 3.2V. This is not good. I reconnected the power switch. 3.2V again. Yet I was getting 4.92V last night :( I don't know what could have changed since last night to cause this massive drop. All I've done is plug in a 5V supply I found this morning. :'(
**edit: I just measured the voltage direct from the 5V monitor cable - it is outputting 5.27V, so plenty on that end of things. Measured the voltage off the expansion port again... still at a crippling 3.2-3.3V
**edit: I just measured the voltage direct from the 5V monitor cable - it is outputting 5.27V, so plenty on that end of things. Measured the voltage off the expansion port again... still at a crippling 3.2-3.3V
As Bryce indicated Probably the Power switch is dirty.
If the volts at the expansion PORT is 3.3v then maybe ADD a WIRE lead from the Expansion port back to the Output of the SWITCH.
Just some thoughts
Good Luck Ray
Quote from: Audronic on 02:56, 17 March 18
As Bryce indicated Probably the Power switch is dirty.
If I am getting the same bad voltage reading both with the switch connected AND shorting the board pins directly, then wouldn't that mean the power switch is having no impact on the voltage problem and therefore not in need of a clean?
OK.
Can you measure the Voltage on Both sides of the SWITCH with the switch turned on ?
It should be the same on both sides.
Ray
Quote from: Audronic on 03:21, 17 March 18
Can you measure the Voltage on Both sides of the SWITCH with the switch turned on ?
I'll have a go, but not sure where i should put the probes, so I tried the following:
Pin 27 to 49 = 3.35V
Pin 27 to left side terminal on power switch = -1.63V
Pin 27 to right side terminal on power switch = -1.62V
Pin 49 to left side terminal on power switch = 4.99V
Pin 49 to right side terminal on power switch = 4.99V
left side switch to right side switch = 0V
Let me know where else I should put the probes and I will post results.
Quote from: blackdalek on 03:45, 17 March 18
I'll have a go, but not sure where i should put the probes, so I tried the following:
Pin 27 to 49 = 3.35V
Pin 27 to left side terminal on power switch = -1.63V
Pin 27 to right side terminal on power switch = -1.62V
Pin 49 to left side terminal on power switch = 4.99V
Pin 49 to right side terminal on power switch = 4.99V
left side switch to right side switch = 0V
Let me know where else I should put the probes and I will post results.
Ok Lets go.
Pin 27 to 49 = 3.35V Not Good-===========-
Pin 27 to left side terminal on power switch = -1.63VPin 27 to right side terminal on power switch = -1.62V
Can you measure from the Small connector BOTH SIDES to Pin 27 Please
-==========-
Pin 49 to left side terminal on power switch = 4.99VPin 49 to right side terminal on power switch = 4.99Vleft side switch to right side switch = 0V
This area is GOOD.
-===========-
Notes I Made earlier
Power Problem CPC6128/464
1) POWER SOCKET is the soldering in good condition ?
Resolder the pins on the POWER Socket
2) The Flying lead from the Power Switch plugs into Connector
CP305 SW POWER is the soldering Good under the board ?
Resolder the 2 pins on the CP305 SW POWER connector
3) Now re test:-
How many volts are you reading on PIN 27 on the EXPANSION CONNECTOR ?
-ve Probe on 0 Volts. +ve Probe on Pin 27
Quote from: Audronic on 04:03, 17 March 18
Can you measure from the Small connector BOTH SIDES to Pin 27 Please
By small connector, I assume you mean the connector on the PCB which I shorted earlier to turn the CPC on?
Pin 27 to left side of PCB power pin = 0V
Pin 27 to right side of PCB power pin = -5.09V
Quote from: Audronic on 04:11, 17 March 18
Notes I Made earlier
Power Problem CPC6128/464
1) POWER SOCKET is the soldering in good condition ?
Resolder the pins on the POWER Socket
2) The Flying lead from the Power Switch plugs into Connector
CP305 SW POWER is the soldering Good under the board ?
Resolder the 2 pins on the CP305 SW POWER connector
3) Now re test:-
How many volts are you reading on PIN 27 on the EXPANSION CONNECTOR ?
-ve Probe on 0 Volts. +ve Probe on Pin 27
Would you like me to resolder
CP305 SW POWER and POWER SOCKET now?
Quote from: blackdalek on 04:22, 17 March 18
Would you like me to resolder CP305 SW POWER and POWER SOCKET now?
Yes please.
After you re solder the above items.
Can you do a test of Pin 27 WITHOUT any expansion items connected. AND WITH
expansion items connected.I am confused by This :-[ Pin 27 to left side of PCB power pin = 0VPin 27 to right side of PCB power pin = -5.09V
Could do the same test with respect to 0 Volts PleaseThanksRay
I have just desoldered connector cp305 and 5V power socket. Now soldered back into place.
retesting...
Pin 27 to left pin of connector cp305 = 0.01V (it was actually 0.01V last time too but I rounded it off to 0V)
Pin 27 to right pin of connector cp305 = -5.09V (same as before)
WITH Z-Mem board only attached to the expansion port....
Pin 27 to left pin of connector cp305 = 0.05V
Pin 27 to right pin of connector cp305 = -4.82V
Ok Well done i think that you have fixed it
One last test
Pin 27 to 0 Volts (Pin 2 ) on the expansion connector what does that read.
Ray
Pin 27 to 0 Volts (Pin 2 ) on the expansion connector what does that read
Place Probe on Pin 27 and the other on Pin2.
Ray
Quote from: Audronic on 05:45, 17 March 18
Ok Well done i think that you have fixed it
Let's not get ahead of ourselves :P
Forget everything you've just read from me in this thread since this morning :P
I have just realised that every measurement I took from pin 27 was actually pin 29 (M1) ...thanks to my short-sightedness and inability to count the correct number of spaces from the keyed slot on the middle of the expansion port :P
I'm pretty sure that was the source of all those 3.2/3.3V measurements I wrote down.
NEW test result from the ACTUAL pin 27 to power switch connector with a Z-Mem connected and power switch unplugged from the PCB...
27 to left pin of CP305 = 0.00 V
27 to right pin of CP305 = -5.15V
NEW test results with Z-Mem connected AND power switch connected and CPC turned on...
27 to 49 = 4.95V
27 to 2 = 4.92V (the 0.03V discrepancy could just be because of the way I was holding the probe on the tiny solder spot on the PCB)
That looks OK only a small Voltage drop
If you want to improve it the have a look in the Picture.
Ray
Nice picture. That wire (the red line) looks like it also connects to R319, C207 and a solder spot in the middle of IC207... but I'll assume it's only meant to go direct from Pin 27 to Pin 1 of CP305.
As for a practical test... SymbOS is still crashing when both the M4 and Z-Mem cards plugged in, but not crashing when the M4 ONLY is plugged in.
So even though the voltage levels look good now, it's still not working as it should.
**Edit: Also, SymbOS loads without crashing when both the M4 and MF2 cards are plugged in. The crash now appears to happen exclusively when the Z-Mem card is attached.
Ok Last one for today.
Can you measure Pin 27 to 0 Volts (Pin2) with both devices connected.
If The Voltage has dropped below 4.85 add the Wire.between Pin 27 of expansion Port and Pin 1 of CP305.
Good luck
Ray
With 2 cards connected, the voltage has not dropped below 4.85V
Is it time to ask @TotO (http://www.cpcwiki.eu/forum/index.php?action=profile;u=290) his opinion on why SymbOS could be crashing while the Z-Mem is connected?
? Are there any switches that are incorrectly set ? on the Z-mem.
Last thought have you ran a Memory test on the 1st 128 K.
Good night
Ray
How do I run a memory test?
The Z-Mem has all its setting switches on same as they were when it arrived (top 2 switches are pushed to the right, left 2 switches are pushed up)
Chibi Akumas Ep1 also doesn't run without crashing when Z-Mem is connected.
Memtest disk
Thank you.
Test.bin crashes after about 10 seconds with Z-Mem connected (I tried 3 times)
With no Z-Mem connected, the test.bin is still running stable while I am typing this post.
Take a Photo of the Switches on the Z-Mem or a drawing so you can put it back to " Standard "
Operate each switch 5-10 times (With the Power Off) and do the test again.
Can you alter the z-mem settings for your 6128
? do the switches do ?
? Can you disable some of the memory ?
Ray
The attached shows where the test.bin program ended (or stalled???) with no Z-Mem attached.
The 4 switches on the Z-Mem are labelled as follows:
CPC: "464" or "6128"
RAM: "64K" or "SET"
"7FFE" or "OFF"
"7FFF" or "OFF"
Current settings are CPC "6128", RAM "SET", "7FFE" and "7FFF"
Going Out now
turn off 7FFF
and try that
Bye
Ray
Switching the 7FFF switch to "OFF" didn't help.
Thanks @Audronic (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1169) for all your kind help today.
Have a great night!
Running the memory tester with only the Z-Mem plugged in directly to the expansion port generates random pixel garbage and frequent crashes and resets. I get the same results running it from the MotherX4 board with or without 5V power supply attached.
@totO I am not sure if this is because my expansion port is still bad or if something is wrong with my Z-Mem card :-[
Can I post my Z-Mem card to one of our Australian technical boffins to examine it for me?
The M4 WiFi card and Multiface2 Card are both working without crashing now. They both co-exist happily together on the MotherX4 board. So the repair work I've done on the expansion port and power switch re-soldering has made some improvement at least.
The Z-Mem card crashing seems to be the only issue I am having now at the moment.
Is it possible to switch off all of the Expanded memory on the Z-Mem ( I don't Have one).
and have it connected to see if the Faults continue.
Good Luck
Ray
I've tried every possible combination of switches. I get garbage on screen and crashing every time any of the memory switches are turned on. I have no idea what the RAM: "64K" or "SET" switch does, but either setting makes no difference. Also the switch CPC: "464" or "6128" makes no noticeable difference either.
Quote from: Audronic on 08:50, 29 March 18
Is it possible to switch off all of the Expanded memory on the Z-Mem ( I don't Have one).
I can post you mine for testing if you like... BTW, did you get your Z80 back OK?
Yes the Z80 has arrived, I have been busy with a major crash on my Mac and the Bl##dy NBN, change of service provider, new email address etc.
My thoughts would be Politely PM TotO for some help he may have some updated documentation to help with the switch positions.
He is a Member on this board.
I could have a look at it But Please ask TotO first.
Is the board well soldered, No connector pins bent etc.
Ray
Well, so far @TotO (http://www.cpcwiki.eu/forum/index.php?action=profile;u=290) has not been in contact with me (I guess he's been away), and I have no other CPC to test with.... so can I post my Z-Mem card to you for testing Audronic? Or does someone closer in Queensland want to have a look at it for me? (I am on Darling Downs area Allora Qld)
Well, I'm still having issues with when connecting the Z-Mem card, so assuming the Z-Mem card is OK (it was tested before shipping) what else can I look at on my CPC6128 to troubleshoot expansion port issues.
Also, can I post my Z-Mem card to someone to test on their CPC just to rule out the possibility that the Z-Mem has somehow become damaged?
Still not found the cause of the problem with my Z-Mem. I don't know what happened to TotO - he seems to have disappeared for now...I have no other CPC to test the Z-Mem with. I really would like to get to the bottom of this and get it working.In short, everything seems to be working with my expansion port now with the exception of the Z-Mem which crashes the CPC consistently and randomly whenever it is connected.
Quote from: blackdalek on 15:02, 06 July 18I don't know what happened to TotO - he seems to have disappeared for now
Just message him directly. He told me he had a really busy month of June, and now he may be available again. He's putting together an X-MEM for me right now.
It's been months since I've had the Amstrad out to tinker with due to all the chaos going on everywhere. Anyway, my CPC's expansion port looks to be fine. All my other expansion devices seem to work fine - original multiface2, modern multiface2 for m4 board, the m4 board itself... however the Z-Mem card is still just causing random garbage and crashing whenever it is plugged in. Toggling the onboard settings switches makes no difference. I will try contacting Toto again, see what he thinks.
Well.... I've had the CPC in storage for past few years while raising my son and I really have not even had time to think about working on my cpc problem. He's almost 5 now so I think it's safe to get the cpc out again.
I've just opened it up and checked the continuity of all the tracks i could see between expansion port and the components, then I also tested continuity of visible tracks from the z80 to other components.
I didn't find any broken traces :(
I still don't know why my expansion port doesn't work. Is anyone willing to give any other advice?
Can I post my cpc to someone who can fix it?
@blackdalek Have you tried an other Z80
as most of the lines go directly to the Z80
Just a thought
Ray
Quote from: Audronic on 14:12, 02 May 22@blackdalek
Have you tried an other Z80
as most of the lines go directly to the Z80
Yes. You actually mailed me one to test with back in 2018 and we had no luck with that either.
@blackdalek I have just repaired a CPC6128, one of the symptoms was a clicking RELAY.
Which is one of your symptoms in the first post.
After testing 20 Ram chips purchased from china and found 14 (FOURTEEN) FAULTY.
I replaced the ram chips that were on the mother board that were faulty with some good ones.
This also stopped the RELAY from clicking.
Perhaps it was an intermittent short in one of the faulty ram chips
Just a thought
Good luck
Keep Safe
Ray
Quote from: Audronic on 23:53, 02 May 22Perhaps it was an intermittent short in one of the faulty ram chips
Just a thought
Sounds plausible. How would I test for that?
Cheers,
Fraser
@blackdalek As you have an M4, can you put Noels Diags into it and run it
and let it do the longer test
I don't use an M4 but I am sure somebody can help
Kep Safe
Ray
@Audronic thanks for the tip.
I found and downloaded Noel's diagnostic program.
With only the M4 board connected, the long "soak" test ran without any errors for 53 iterations before I quit it.
I made several attempts to run it with the z-mem board attached but it was impossible. CPC crashed spectacularly within 3 seconds every time. Random screen garbage, tape relay clicking, disc drive motors starting etc.
I made some short videos of the CPC Diagnostics test running.
First video shows the CPC with only the M4 board connected. The soak test runs normally forever until aborted by user.
Next video shows affects of running upper RAM test with Z-Mem board attached.
and once more... This time with nice error bars screen at end.