Oric Atmos resets after a few seconds ... when not grounded

If you want to ask questions about how the machine works, peculiar details, the differences between models, here it is !
How to program the oric hardware (VIA, FDC, ...) is also welcome.
Godzil
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Re: Oric Atmos resets after a few seconds ... when not groun

Post by Godzil » Tue Mar 03, 2015 11:01 am

Chema: no this is not stupid, as heat make copper contract or expand, a micro cut could do a lot of things.

As the most hot point on the Oric mother board is around the 7905 I would search there first.

Also the wire mess on your oric bother me, I hadn't had time to check everything, but there is still one wire that I can't explain right now.

By the way, if you have an EPROM programmer, maybe you have some empty compatible eprom, there are some test rom for the oric, you could try to burn one, and test your oric with it to see, it if still reset, it would mean that the ROM is not a problem and there is a nasty hardware problem, but if the reboot is because of a faulty chip other than the ULA or the 6502, the test ROM could help to find the culprit.

For a possible microcut, I thing you could do, is to take apart your oric, unplug the keyboard, so leaving only the mother board, plug the screen, the power, and genlty, really gently, bend the board, if there is a microcut on a track it may bring out.

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Re: Oric Atmos resets after a few seconds ... when not groun

Post by TomPhobos » Tue Mar 03, 2015 11:48 pm

Hmm, a micro cut could really be. I measured some main tracks, but i really should measure the voltages and some more lines. And yes, the wire mess is also really strange. Maybe a wrong mod, a broken cable or noise on the wires causes the problems.
Yes, i have an EPROM programmer. But i don't know if a single EPROM would work, because my Atmos has 2 EPROMs. Maybe here i also need a LO and a HI ROM.

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kenneth
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Re: Oric Atmos resets after a few seconds ... when not groun

Post by kenneth » Sun Apr 05, 2015 11:29 am

I think that a ghost signal appears in the RESET pin of the 6502A. IT happens easily with a floating voltage

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Re: Oric Atmos resets after a few seconds ... when not groun

Post by TomPhobos » Mon Apr 20, 2015 3:43 pm

Hmm, that could be ... but the question is, what causes this problem and how can i solve it?
Actually i haven't done much in the last weeks with my Oric. In june i'm at a computer meeting. One of the visitors has an oscilloscope. He is great in repairing computers, so i hope that he will find (and fix) the problem :)

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Re: Oric Atmos resets after a few seconds ... when not groun

Post by Godzil » Mon Apr 20, 2015 4:01 pm

Don't forget to dump the ROM of your german keyboard oric :)

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Re: Oric Atmos resets after a few seconds ... when not groun

Post by TomPhobos » Mon Apr 20, 2015 4:06 pm

Oops. yes. you are right :oops:
Well, i haven't looked at my Oric for a long time ( i know, what a shame ;) ) so i totally forgot it. I hope i'll find the PSU of my "Eprom burner Win98-Laptop" so i can dump the ROMs (2 EPROMs) next weekend.

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Re: Oric Atmos resets after a few seconds ... when not groun

Post by Godzil » Mon Apr 20, 2015 4:09 pm

Thanks :)

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Re: Oric Atmos resets after a few seconds ... when not groun

Post by Symoon » Mon Apr 20, 2015 7:01 pm

As an alternative, CSAVE"ROMGER",A#C000,E#FFFF would do it!
Mmmmh, that is, of course, if you can keep the Oric running long enough without rebooting.

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Re: Oric Atmos resets after a few seconds ... when not groun

Post by Godzil » Tue Apr 21, 2015 9:49 am

And you have a tape cable :D

But that a solution :D

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