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Defective Oric 1 and Atmos ... need help for a repair ...


YuT666
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Hi,

 

got two defective Orics (1 and an Atmos) and both show bad screens. It looks like a defective cpu and/or defective rams.

 

So i'm searching for someone, who had similar problems and tried to repair an Oric and could tell something about this ...

 

Both seem to have an ordinary 6502A CPU, so a replacement would be easy (i think).

 

Thanks in advance ...

 

Tom

 

 

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Thanks for your help ...

 

Yeah, i know the defence-force board and i'll check your link.

 

I hope i'll fix one of the Orics in the next two holiday weeks. Would be great. I'll open them and check what's socketed and whats not ... i've some spare 6502 for first test.

Edited by YuT666
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Are you using the same power supply to test both units?
If the voltage output is off it might cause this.

The simplicity of the design usually makes the Oric pretty reliable.
Lets face it, there aren't a lot of things to fail.
RAM would be the next thing I'd check after power, then the ULA.

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Thanks for your answer James.

 

I now tried two different universal power supplies ... the same result.

 

The RAMs are all only warm, not hot (both computers). I don't think, that this is a RAM problem.

 

I will shorten pin 1 und 40 tomorrow, 'cause the reset switch ist only for NMI.

 

I went to the defence-force board, 'cause there are some Oric freaks there, but ... i really appreciate all your help and it is welcome ...

Edited by YuT666
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  • 1 month later...

Ok, bought some UM6502 in Ireland ... i desoldered the old cpu of the Oric 1 and soldered a socket (my first socket so far) ... put the first cpu in ...

post-47392-0-83726600-1487001475_thumb.jpg

... AND ...

 

post-47392-0-05796100-1487001479_thumb.jpg

Tried some keys and they works so far. I'll test the Oric 1 with a test ROM, so i hope, that the cpu was the only bad component ...

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As I mentioned on Defence-Force, usually the 6502 is not the first chip to go bad but apparently this was exactly the cause here. Perhaps it depends on the application, in Commodore PETs and subsequent computers there are more chips that go bad before the CPU but perhaps the Oric interfaces it differently.

 

Congratulations!

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Atmos:

I desoldered the old cpu and put a socket in. Tried three different cpus and the Atmos still has the same issue (the pattern i showed in the first post). I checked the socket again and again, but that changed nothing. All cpus worked with the Oric 1, so there must be an other problem. I piggybacked all RAMs ... nothing. Crap.

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Yes, i know ... i'll transfer the issue 3 board into the Atmos case (and put the V1.1 in the rom socket), so i've time to repair the issue 4 board. I get an 6522 in the next days, so i hope, that this one caused the error.

Edited by YuT666
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  • 5 years later...

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