Print Page - CPC 464 is not working (after overvoltage ?)

Title: CPC 464 is not working (after overvoltage ?)
Post by: Snocksman on 21:50, 14 July 22

Hi !

I got my first Amstrad CPC 464 a week ago. It came to me without the Display and without the Power suppy, so i used the Universal Power supply that i use for my Commodore plus4. Before i connected it to the CPC I looked up the right voltage and polarity. I set up the right polarity and started up the CPC and yes, i forgot the voltage, so i gave the 9V (setting for the Plus4) to the CPC :doh: I really don't know If it was working before, but now it doesn't.

So I started to repair it... Here is what I have done allready:
- Replaced all RAM ICs (tested the RAM in the Plus4, before)

- Burned a Diag-ROM and replaced the Amstrad 40009 Chip with it

- replaced IC114

- replaced ICs 104, 105, 109 & 113 (Multiplexer)
- checked ICs 112 & 115 with TL866 (both OK)

After all the Diag ROM Displays this Screen to me:
IMG20220709184015__01.jpg

Looks to me like all RAM ICs are defektive, but they really work ! 100% !

What else could i try to get my CPC 464 running ?

Title: Re: CPC 464 is not working (after overvoltage ?)
Post by: TotO on 21:56, 14 July 22

May be 373 or 244 ...

Title: Re: CPC 464 is not working (after overvoltage ?)
Post by: Snocksman on 22:06, 14 July 22

The 373 (IC114) has allready be replaced by a new one and the 244 (IC115) has been tested in my TL866 programmer and should be OK.

By the way... Is it possible to switch the Board on without the little PCB for the Datasette (by bridging two Pins, or so)?
IMG20220707185052__01__01.jpg

Title: Re: CPC 464 is not working (after overvoltage ?)
Post by: Snocksman on 08:12, 15 July 22

What about the big Chips ? The Zilog CPU and the 40010 GateArray... If one of these would be faulty, would i get a picture on Screen from the Diag ROM ?

Title: Re: CPC 464 is not working (after overvoltage ?)
Post by: pelrun on 10:18, 15 July 22

Getting a working RAM check display from the diag ROM requires the Z80, GA and CRTC to be almost fully functional.

Title: Re: CPC 464 is not working (after overvoltage ?)
Post by: TotO on 10:20, 15 July 22

If you got the RAM diag screen, that mean you can display properly because the Z80, the CRTC and the GA are working. If, they are all RED, it is because the program can't write/read the RAM to report a good status. (faulty RAM or 373/244 IC).

Title: Re: CPC 464 is not working (after overvoltage ?)
Post by: Snocksman on 12:22, 15 July 22

I got my CPC back to life !!! I cleaned the PCB and found two broken tracks. I replaced them and now it works !

IMG20220715124623__01__01__01.jpg

Title: Re: CPC 464 is not working (after overvoltage ?)
Post by: TotO on 13:43, 15 July 22

Congratulations!!! :D
Now, you can try the next level using 12V... :-\

Title: Re: CPC 464 is not working (after overvoltage ?)
Post by: Snocksman on 15:54, 15 July 22

Hey, cool Idea ! The new Game for the whole Family... Roast, repair, repeat ! :picard:

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General Category => Technical support - Hardware related => Topic started by: Snocksman on 21:50, 14 July 22