Hey and thanks for letting me join. I purchased a CPC464 with Green screen and a bunch of games for a bargin prices over the weekend, had one as a kid and wished I'd never let it go. Anyway's up shot if when it's powered on all I get is a Green Box on the display, from what I have read this seems to indicate a faulty RAM chip, the tape deck fasts forward and rewinds but there are no beeps if you press any keys? I have pulled it all apart and given it a good clean, but is there anything else that I could do while waiting for RAM? Thanks Alex
That doesn't look like a RAM problem to me, it looks either a monitor problem or an ASIC problem. Does it beep when you press the DEL key? Make sure to turn the volume wheel up.
No, nothing happens when you the volume is on and I press Del.
@abalore , for these cost reduction boards does the ASIC include the 6845 CRTC functionality?
Quote from: Wobble_master on 16:16, 05 November 24No, nothing happens when you the volume is on and I press Del.
Next thing you can try is an external diagnostics cartridge, but if you don't want to waste more money, wait for the RAM and cross fingers. If it's the ASIC you'll have a beautiful brick. You can also send the motherboard to me for fixing, just for the cost of shipping and required components.
I'll leave a video on how to use a diagnostics tool:
Quote from: Rabs on 17:24, 05 November 24@abalore , for these cost reduction boards does the ASIC include the 6845 CRTC functionality?
Yes
Thanks, where can I get the diagnostics cartridge from? I may well take up on the repair if I'm unable to resolve. I have an external power and cable on order to eleminate the screen as being the problem.
Quote from: Wobble_master on 17:40, 05 November 24Thanks, where can I get the diagnostics cartridge from? I may well take up on the repair if I'm unable to resolve. I have an external power and cable on order to eleminate the screen as being the problem.
here is the hardware:
https://rancanuoteam.com/producto/cpc-mini-dual/
then you can install the diagnostics software as explained in the video.
Excellent, will have a look at this once I have checked the other parts.
Hi,
that looks very much like a dead ASIC. Have you checked the temperature of it? If you have a multimeter or a scope there are some pins you could check to confirm that it's a dead ASIC.
Bryce.
I've checked chip temps and nothing is getting overly warm, I have a multimeter if you can advise on the chips and pins to check that would be fab
Quote from: Rabs on 17:24, 05 November 24@abalore , for these cost reduction boards does the ASIC include the 6845 CRTC functionality?
I was wondering what you guys were talking about when reading this thread on my mobile phone without being logged in (so I would not see any attachments).. Anyhow, now I am reading from my laptop and can see the images
@Wobble_master attached. I think I have never seen a mainboard like the one in the first post. Is IC101 the ASIC you are talking about? What are IC102 and IC103 doing?
Quote from: BSC on 21:57, 05 November 24Quote from: Rabs on 17:24, 05 November 24@abalore , for these cost reduction boards does the ASIC include the 6845 CRTC functionality?
I was wondering what you guys were talking about when reading this thread on my mobile phone without being logged in (so I would not see any attachments).. Anyhow, now I am reading from my laptop and can see the images @Wobble_master attached. I think I have never seen a mainboard like the one in the first post. Is IC101 the ASIC you are talking about? What are IC102 and IC103 doing?
As part of my research for a fix, I only saw 1 other board like this one and they used it to show the variety of revisions, if memory serves its D1. My 1st concern were the 2 black wires, but they showed the same on the other one I saw.
Bit more research on here and it looks like it was the last board produced:
Board: PT NO Z80329, MC0099A, Copyright 1988
MC0099A board fitted with 2x41464 (64Kx4 bits) chips instead of 8x4164 (64Kx1 bit) chips.
https://www.cpcwiki.eu/index.php/Mainboard_Versions
Quote from: Wobble_master on 22:22, 05 November 24Bit more research on here and it looks like it was the last board produced:
Board: PT NO Z80329, MC0099A, Copyright 1988
MC0099A board fitted with 2x41464 (64Kx4 bits) chips instead of 8x4164 (64Kx1 bit) chips.
https://www.cpcwiki.eu/index.php/Mainboard_Versions
I've just noticed that on the image shown on here of my board there are 2 chips above the RAM, on my board they are missing?
Mine matches this board:
Board: PT NO Z80329, MC0099A, Copyright 1988
Tiny mainboard. Uses 100pin SMD Gate Array (combines the old Gate Array, CRTC, and some FDC/DRAM/RESET logic in one chip).
But has D1 as a revision, the board above has D2
QuoteI've just noticed that on the image shown on here of my board there are 2 chips above the RAM, on my board they are missing?
The board can use either 8x4164 chips or 2x41464 chips as ram options.
Yours obviously is using eight 4164 ram chips, so no missing chips on your board.
Thanks for confirming the board type.
Quote from: Wobble_master on 20:56, 05 November 24I've checked chip temps and nothing is getting overly warm, I have a multimeter if you can advise on the chips and pins to check that would be fab
If you take a look at the GX4000 or CPC+ Schematics you can see the full ASIC pinout and functions. I'd start by checking the CLK signals and then move on to outputs to the DAC. However, before doing any of that, I'd try swapping out the CPU.
Bryce.
Quote from: Bryce on 16:18, 06 November 24Quote from: Wobble_master on 20:56, 05 November 24I've checked chip temps and nothing is getting overly warm, I have a multimeter if you can advise on the chips and pins to check that would be fab
If you take a look at the GX4000 or CPC+ Schematics you can see the full ASIC pinout and functions. I'd start by checking the CLK signals and then move on to outputs to the DAC. However, before doing any of that, I'd try swapping out the CPU.
Bryce.
've got the schematics to reference pins, just to confirm is this a continuity test with the power on to the board?
Thanks
Quote from: Wobble_master on 18:18, 06 November 24Quote from: Bryce on 16:18, 06 November 24Quote from: Wobble_master on 20:56, 05 November 24I've checked chip temps and nothing is getting overly warm, I have a multimeter if you can advise on the chips and pins to check that would be fab
If you take a look at the GX4000 or CPC+ Schematics you can see the full ASIC pinout and functions. I'd start by checking the CLK signals and then move on to outputs to the DAC. However, before doing any of that, I'd try swapping out the CPU.
Bryce.
've got the schematics to reference pins, just to confirm is this a continuity test with the power on to the board?
Thanks
No, you should check if any voltage or signal is present on each pin while the CPC is running.
Bryce.
Thanks, will be the weekend now.
Quote from: abalore on 17:37, 05 November 24Quote from: Wobble_master on 16:16, 05 November 24No, nothing happens when you the volume is on and I press Del.
Next thing you can try is an external diagnostics cartridge, but if you don't want to waste more money, wait for the RAM and cross fingers. If it's the ASIC you'll have a beautiful brick. You can also send the motherboard to me for fixing, just for the cost of shipping and required components.
I'll leave a video on how to use a diagnostics tool:
Quote from: Rabs on 17:24, 05 November 24@abalore , for these cost reduction boards does the ASIC include the 6845 CRTC functionality?
Yes
@abalore , I have a Dandanator on order if I get nothing from this I'd like to take you up on the repair as I could spend a fortune on just replacing parts, and tools to do so.
Quote from: Wobble_master on 13:48, 11 November 24Quote from: abalore on 17:37, 05 November 24Quote from: Wobble_master on 16:16, 05 November 24No, nothing happens when you the volume is on and I press Del.
Next thing you can try is an external diagnostics cartridge, but if you don't want to waste more money, wait for the RAM and cross fingers. If it's the ASIC you'll have a beautiful brick. You can also send the motherboard to me for fixing, just for the cost of shipping and required components.
I'll leave a video on how to use a diagnostics tool:
Quote from: Rabs on 17:24, 05 November 24@abalore , for these cost reduction boards does the ASIC include the 6845 CRTC functionality?
Yes
@abalore , I have a Dandanator on order if I get nothing from this I'd like to take you up on the repair as I could spend a fortune on just replacing parts, and tools to do so.
perfect, will send you a PM
60Hz set.... maybe
@Wobble_master have You oscilloscope or multimeter ?
Quote from: McArti0 on 14:53, 11 November 2460Hz set.... maybe
@Wobble_master have You oscilloscope or multimeter ?
We already stated that the unit doesn't beep when DEL key is pressed after turning on, so it's something more than just the bad image.
Quote from: McArti0 on 14:53, 11 November 2460Hz set.... maybe
@Wobble_master have You oscilloscope or multimeter ?
I have a multimeter and logic probe, I'm struggling with the schematics against the later costs down board saving board in mine. Has anyone got a basis diagram of the layout.
Internet not remember pinout ASIC3 AMS40226 :-X
Quote from: McArti0 on 15:37, 11 November 24Internet not remember pinout ASIC3 AMS40226 :-X
Found the pin out for the ASIC
Try found 4MHz Clock signal on Pin6 CPU and 1MHz on WAIT signal on PIN24 CPU with duty 25%
Quote from: McArti0 on 16:20, 11 November 24Try found 4MHz Clock signal on Pin6 CPU and 1MHz on WAIT signal on PIN24 CPU with duty 25%
I think I'd need an oscilloscope for that, all I have is multimeter and logic probe.
Thanks 🙏
Add photo this multimeter and logic probe
Quote from: McArti0 on 16:38, 11 November 24Add photo this multimeter and logic probe
[(https://www.dropbox.com/scl/fi/x1dl6ohv0tlx9k69gg3pv/IMG_4732.jpg?rlkey=7s184du3vxe1xkmfka2ab0me5&st=g3o9b06f&dl=0)]
Hopefully you can see the image?
Preview and Click or drag files here to attach them.
https://www.dropbox.com/scl/fi/x1dl6ohv0tlx9k69gg3pv/IMG_4732.jpg?rlkey=7s184du3vxe1xkmfka2ab0me5&st=g3o9b06f&dl=0 (https://www.dropbox.com/scl/fi/x1dl6ohv0tlx9k69gg3pv/IMG_4732.jpg?rlkey=7s184du3vxe1xkmfka2ab0me5&st=g3o9b06f&dl=0)
Image of the Meter and logic probe
Quote from: McArti0 on 17:14, 11 November 24Preview and Click or drag files here to attach them.
Got it, thanks 👍
Ok use oscillophone.
Set speeker volume louder.
Cross Pin1 expansion port (sound) and Pin16 CPU (INT) You should hear 300Hz sound.
Try this on Synchro Pin videoPort too (60Hz)
Quote from: McArti0 on 18:52, 11 November 24Ok use oscillophone.
Set speeker volume louder.
Cross Pin1 expansion port (sound) and Pin16 CPU (INT) You should hear 300Hz sound.
Try this on Synchro Pin videoPort too (60Hz)
Will give this a try tomorrow, also order this to help
Its not help
Minimum is DPOX180H
Quote from: McArti0 on 18:52, 11 November 24Ok use oscillophone.
Set speeker volume louder.
Cross Pin1 expansion port (sound) and Pin16 CPU (INT) You should hear 300Hz sound.
Try this on Synchro Pin videoPort too (60Hz)
You only need one wire for this.
Quote from: McArti0 on 01:09, 12 November 24Its not help
Minimum is DPOX180H
Is this just because its doesn't have a probe? Will try you suggestion tomorrow.
DSO152 mini 2,5MSa/s 200KHz ... You need 100-200 times more ...
Board fixed, it was a bad RAM IC
@Wobble_master but you at least should have been able to see the screen geometry, so don't discard the monitor is also broken. A 2x1 scam :(
Quote from: abalore on 17:58, 19 November 24Board fixed, it was a bad RAM IC
Wow can't wait to get it back and have a play. Might not be everyone taste but I loved the Dizzy games.
Quote from: abalore on 18:04, 19 November 24@Wobble_master but you at least should have been able to see the screen geometry, so don't discard the monitor is also broken. A 2x1 scam :(
I have no plans to get rid of the green screen as that will complete my 80's experience of having a CPC464 😊
Massive thanks to
@abalore for fixing my CPC board, just playing Bomb Jack 👌👌👌👌