Talent DPC200 issues

Supporter (4)

27-03-2022, 05:47

Hello everyone!
I'm experimenting the following issues with my Talent DPC 200, looking for ideas for troubleshooting or where to search to fix it:

1-At start, shows this screen with vertical white lines.

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2-After some seconds, it changes to this one (supposedly i'ts the basic screen), filled with bold white vertical lines.

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3- When I press the keys, they made the appropiate sound.

4- I've tried to load a .Cas file via MSX2CAS app. Despite I am not able to see what I'm doing on screen, I typed the command carefully, letter by letter, guided by the keys sound. But it didn't worked, nothing loaded.

4-Caps lock turns on when pressed.

5-typed the command [play"abc"] but it didn't worked.

Could it be the VRAM? It has TMS4416-20NL chips, I ordered two of them by the way.
Could a bad VRAM prevent from loading games or execute the command "Play"ABC"?

Looking forward from your valuable comments! Thanks in advance!

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Par mohai

Paladin (971)

27-03-2022, 13:32

Hello.
Sorry. Your screenshots aren not shown.
I would try to test solder points. Check for bad solder in the board.
I got myself a DCP 200 (Dynadata) that was not starting at all. After checking some chips (PPI, clock, Z80...), it suddenly started normally. I double checked and found that there was a bad solder in a chip after the PPI. Removed the tin and soldered again. It is workin normally now.
This model often has some fixes in the board, factory-made. Pleade check them too.

You said the PLAY command is not doing any sound but, can you hear CLICK sound? If so, then check for sound output from PSG too or audio connector (bad solder again?)
Can you hear BEEP sound at startup or if you press ctrl+g ?

Par Manuel

Ascended (18858)

27-03-2022, 21:51

I think that commands entered in BASIC are read from VRAM when they get executed. So yes, faulty VRAM could probably interfere.

Par BillyLee

Supporter (4)

28-03-2022, 04:38

Thanks guys for your comments and tips, very appreciated!!
I'll wait for the replacement VRAM chips and will let you know the results.

Yes, I can hear the beep sound at startup and the keyboard is making sounds when the keys are pressed.
The capslock also lit when pressed.

Thanks again for your support!

Par BillyLee

Supporter (4)

28-03-2022, 04:55

These are the screens:

At startup:

Once started (supposedly basic screen)

Par BillyLee

Supporter (4)

29-03-2022, 22:18

Hi guys, finally fixed!! It was the VRAM chips. Installed new ones with sockets and all it's working now! :-) Thanks for your support!

Par mohai

Paladin (971)

31-03-2022, 11:01

Manuel wrote:

I think that commands entered in BASIC are read from VRAM when they get executed. So yes, faulty VRAM could probably interfere.

I do not think so. There is a command line buffer in RAM.

I am glad to hear your computer is fixed.
DPC-200 has no engine on it. Only discrete logic, so it is easy to diagnose and fix.