Author Topic: My 6128 does not work with my Mother x4 with addons  (Read 3836 times)

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Offline kribjo

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Hi,I have a 6128 bought 2014 on ebay with a "pico" (in quotes as its probably not original Pico) psu with ac/dc adapter and 3.5" disk drive. Works as it should without anything connected. However connecting my Mother X4 with addons and it restarts all the time and with a clicking sound. Some times it just hangs. And even more seldom it works. Using the Mother X4 and addons on my 664 is no problem.  It works 10 out of 10 times on my 664. I did a continuity check with my multimeter on the 6128 from the 50 "dots" on the pcb to through the extension cable to the Mother X4  side and no problem. I even used swab and Isopropyl Alcohol (IPA) - 99.8%. I believe the issue might between the "dots" and lines to the other components on the pcb. Do anyone have some tips on how to do a debug on this and perhaps how I can fix it?


I would like to add some images showing the pcb, but I get an error when uploading. Will upload later.
I linked to my image at Google Photos in the mean time. Image of pcb.

Bjørn.
« Last Edit: 01:10, 30 January 16 by kribjo »

Offline pelrun

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #1 on: 10:59, 30 January 16 »
The edge connector is pretty marginal (especially after 30 years of dirt and corrosion buildup); the more addons you have the harder it is to get a reliable setup. Cleaning the connector, or using the external power input on the MotherX4 may help.


(in the end I got fed up with the edge connector and soldered locking 0.1" headers to them instead, which solved my connection issues. But it's a pretty drastic step.)

Offline Munchausen

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #2 on: 11:04, 30 January 16 »
The edge connector is pretty marginal (especially after 30 years of dirt and corrosion buildup); the more addons you have the harder it is to get a reliable setup. Cleaning the connector, or using the external power input on the MotherX4 may help.


(in the end I got fed up with the edge connector and soldered locking 0.1" headers to them instead, which solved my connection issues. But it's a pretty drastic step.)

+1. I ended up soldering pin headers on to one of my CPCs. I actually still had issues afterwards though. Something very odd about those edge connectors sometimes.

Offline TotO

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #3 on: 11:40, 30 January 16 »
No need to soldering anything... And the external PSU is only required when the CTM is not enough to power the CPC and the expansions.

The best is to clean the expansion connector sides with cotton swabs and 70% alcohol, while they stay not white.
Next, to plug and unplug the edge connector some times and see the result.
« Last Edit: 11:50, 30 January 16 by TotO »
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Offline pelrun

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #4 on: 12:33, 30 January 16 »
No, there's no need for soldering anything if the other solutions work, obviously. But it absolutely and permanently fixed all the issues I'd been having, when nothing else did.

Offline Munchausen

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #5 on: 13:29, 30 January 16 »
No, there's no need for soldering anything if the other solutions work, obviously. But it absolutely and permanently fixed all the issues I'd been having, when nothing else did.

Yeah I think sometimes cleaning is not enough. I had also tested with a meter and all connections showed up as fine, with no shorts.

Offline TotO

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #6 on: 13:51, 30 January 16 »
If the CPC expansion connector was never used into the past and the CPC not stored under the rain, cleaning is enough.  ;D
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Offline Munchausen

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #7 on: 16:56, 30 January 16 »
If the CPC expansion connector was never used into the past and the CPC not stored under the rain, cleaning is enough.  ;D

Not always! SYMBiFACE edge connector issues

Offline OCT

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #8 on: 20:59, 30 January 16 »
Hi,I have a 6128 bought 2014 on ebay with a "pico" (in quotes as its probably not original Pico) psu with ac/dc adapter and 3.5" disk drive. Works as it should without anything connected.
This rare (for a CPC) type of power supply does raise a flag to check whether any ripple, induction or other interference might cause issues as soon as extra hardware increases the load.
Are you anywhere near a scope (or multimeter with a port for repeated measurements) ?

Offline 1024MAK

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #9 on: 05:52, 31 January 16 »
I think we need to start with the basic test of the +5V power lines.

So please use a multimeter to test between the 0V (GND) and +5V (VCC) terminals of the MotherX4 board. See this wiki page for details of the computer end. Do the first test with NO expansions plugged into it. Switch the computer on. Record the exact voltage. Wait for 2 minutes. Record the voltage again. Switch off. Connect up the expansions. Switch the computer on. Record the exact voltage. Wait for 2 minutes. Record the voltage again. Switch off

Post the results here, along with details of the multimeter that you are using.

Mark
 
Looking forward to summer in Somerset :-)

Offline kribjo

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #10 on: 17:05, 31 January 16 »
I have swabbed the expansion port with IPA multiple times. My Mother X4 have an external psu which I always use.

I do not have any experience in electronics or use of multimeter other than measuring continuity, and limited time. But hey, I can learn something new here. Definitely gonna figure this out.  :) I'll investigate the schematics and give it a try OCT and 1024MAK. I believe my multimeter can do repeated measurements (UNI-T UT61D).

Bjørn

Offline kribjo

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #11 on: 19:28, 31 January 16 »
Game of elimination. I've removed my HxC Floppy Disk Emulator during testing.


One more try with my 664 and Mother X4 Main Board w/ext. psu + MiniBooster MX4 Board + X-MASS MX4 Board + X-MEM MX4 Board (swithes cpc:6128, boot:rom, rom:free) . OK. Working as is should.


Removing all cards and connecting only Mohther X4 Main Board w/ext psu to 6128. OK. Working as it should.
Adding Miniboster MX4 Board. OK. Working as it should.
Adding X-MASS MX4 Board. OK. Working as it should.
Adding X-MEM MX4 Board (swithes cpc:6128, boot:rom, rom:free). Fail.


Connecting X-MEM MX4 directly to 664 expansion port without Mother X4. OK. Working as it should.
Connecting X-MEM MX4 directly to 6128 expansion port without Mother X4. Fail.

I have not spent to much time on loading rom-files, but as said previously it has worked om seldom occasions on my 6128. But maybe I have loaded ROM's one time and forgot to test on 6128. But why then is it working on 664 and not 6128?
ROM List on my 664. Have I missed out on something in my ROM list?

Bjørn
« Last Edit: 20:49, 31 January 16 by kribjo »

Offline TotO

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #12 on: 22:20, 31 January 16 »
What is your 6128 mainboard serial?
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Offline kribjo

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #13 on: 22:54, 31 January 16 »
Serial: 209739 K32-5X.

Offline TotO

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #14 on: 23:29, 31 January 16 »
Is printed "PT NO Z80330" over the CPU and "MC0100A" under the RAM chips ?
This PCB: http://www.cpcwiki.eu/imgs/8/80/CPC6128_PCB_Top_%28Z80330_MC0100A%29.jpg
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Offline kribjo

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #15 on: 00:17, 01 February 16 »

I think it must be Board: PT NO Z70290, MC0020A, ECMKI-94HB, Copyright 1985.
However I cannot find MC0020A on my motherboard.


Picture of my motherboard.
 [ Invalid Attachment ]


Bjørn

Offline Bryce

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #16 on: 00:21, 01 February 16 »
The Z80 pins don't look great. I'd remove the chip, clean the pins and re-insert it. It probably won't solve your problem, but it's not doing you any favours like that.

Bryce.

Offline Terje_Norway

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #17 on: 00:44, 01 February 16 »
I think it must be Board: PT NO Z70290, MC0020A, ECMKI-94HB, Copyright 1985.
However I cannot find MC0020A on my motherboard.


Picture of my motherboard.
 [ Invalid Attachment ]


Bjørn


Hi Bjørn,


You could find the text "MC0020A" on left side of the board, just above the cutout of the board.
Just below the joystick connector and the other connection on the left of Your computer, very close to the keyboard connection.
You'll probably find it now.


Yours

Terje Grind
NORWAY

PS Your machine is made in Korea October 1985.

Offline OCT

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #18 on: 01:11, 01 February 16 »
I believe my multimeter can do repeated measurements (UNI-T UT61D).
Should make a nice USB logger indeed, showing if the voltage goes haywire.

Inductive (or HF) interference is another matter, considering that (as I understand your initial description) a DC/DC switching PSU with a transformer probably operating at several hundred kHz has been transplanted into the CPC 6128 (German models of which were actually sold with an extra shield, albeit possibly more to limit EM emanations rather than ingress):
I wouldn't rule out some part of the machine or unshielded wires to the X4s nearby could get troubled by these frequencies or harmonics thereof.

Offline 1024MAK

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #19 on: 03:56, 01 February 16 »
Connecting X-MEM MX4 directly to 664 expansion port without Mother X4. OK. Working as it should.
Connecting X-MEM MX4 directly to 6128 expansion port without Mother X4. Fail.

I have not spent to much time on loading rom-files, but as said previously it has worked om seldom occasions on my 6128. But maybe I have loaded ROM's one time and forgot to test on 6128. But why then is it working on 664 and not 6128?
ROM List on my 664. Have I missed out on something in my ROM list?
Strange, it looks like the 664 is happy with X-MEM, but the 6128 is not  :-\

Do you have any other expansions to test on your 6128?

Clean the pins on the Z80 CPU and retest. If the CPU in your 664 is in a socket, you could try swapping the two Z80 CPUs around to see if the fault follows the CPU (or not).

Mark


Looking forward to summer in Somerset :-)

Offline pelrun

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #20 on: 04:58, 01 February 16 »
Sounds like one or more address lines on the 6128 expansion port is bad/marginal. Minibooster and X-MASS only decode a few addresses, but the X-MEM uses all of them.


Edit: if so, it's really unlikely to be a problem with the z80 chip itself - because you would have all sorts of other problems then.

Offline pelrun

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #21 on: 05:14, 01 February 16 »
Simple way to check the address lines - there should be a good low-resistance path from a z80 pin to the associated MotherX4 pin. Connect the MotherX4 by itself, then refer to the pinouts of the z80 and the expansion port and check the resistance between the z80 pin and the respective pin on the MotherX4. If one or more is much higher resistance than the others, or outright open-circuit, then there's your culprit.


Z80 pinout: Thomas Scherrer IC Pinouts
Expansion pinout: Connector:Expansion port - CPCWiki (the MotherX4 ports are identical, obviously)

Offline TotO

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Re: My 6128 does not work with my Mother x4 with addons
« Reply #22 on: 08:35, 01 February 16 »
Picture of my motherboard.
Try to exchange the CPU... If it work, I will send to you a new one.
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