Oric Atmos to bring back to life!

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.
Wolfo
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Oric Atmos to bring back to life!

Post by Wolfo »

Dear Group,
I am new and this is my first post.
I have been given a Oric Atmos and I have seen working for only some seconds before he decided to "crash" :(
I started looking over the internet for help and I have found this Group only devoted to Oric computers! :)

Now the computer is stuck and I can see what in the attached picture.
I also attach a picture of the mobo.
Does somebody recognize the pattern?
Any ideas?

Thank you for your help, support and experience,
Flavio
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Dbug
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Re: Oric Atmos to bring back to life!

Post by Dbug »

Looks like some of the ram chips have been changed, so possibly the machine suffered some problems in the past.
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iss
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Re: Oric Atmos to bring back to life!

Post by iss »

@Wolfo: Welcome at DF forum!

+1 for faulty RAM chips.
What PSU are you using?
What testing equipment do you have (scope, multimeter, etc.) :?: , so we know which spells to suggest for the "resurrection".
Wolfo
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Re: Oric Atmos to bring back to life!

Post by Wolfo »

Hello. I use the original PSU and I have checked the voltages, that "seems" ok.
If helpful I can measure the voltages when the PSU is not connected and when connected to the Oric (not the Oric is open).
In case I could also use a modern PSU with voltage regulator that I normally use with computers that needs special voltages and connectors.

I have a multimeter that I normally use for "easy checks".
I have also access to an oscilloscope but I do not know how to use it... in case I really need to be driven (put this sensor there... change that in this way and so on...)... please forgive me but I am not a technician... :(
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Dbug
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Re: Oric Atmos to bring back to life!

Post by Dbug »

You can use the finger to check the temperature on the ram chips.
Let the machine run for a while, then put your finger on the ram chips and if one (or more) is much warmer than the other, it may be damaged.

A diagnostic cartridge/rom could also help, do you have a way to program some eproms?
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Re: Oric Atmos to bring back to life!

Post by Wolfo »

I have already finger checked everything and I feel no warmer chips like I have felt in other cases.
I have an EPROM programmer... it's it possible to burn a special EPROM test chip?
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Dbug
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Re: Oric Atmos to bring back to life!

Post by Dbug »

Yup, you can download it on Mike Brown's site:
https://oric.signal11.org.uk/html/diagrom.htm
Wolfo
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Re: Oric Atmos to bring back to life!

Post by Wolfo »

Thank you... :-)
Now I have an issue... I was looking for a 27128 and... I have found a world!
What do I have to search for... M27128? 27C128? 27C128-SO? HELP!!!
I normally use TME but they do not have anything.
I was so looking on https://www.questcomp.com/ but there are so many different possibilities I am confused... :-(
I am afraid to ruin (more) the Atmos... :-|
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iss
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Re: Oric Atmos to bring back to life!

Post by iss »

Hm, time flees ... and normal UV EPROMs 16k x8 are impossible to be found as new parts.
It seams the only source is ebay like sites with all the risks to receive fake chips ... :(.

Here is a quick search.
Avoid China suppliers, although I personally don't have bad experience.
Wolfo
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Re: Oric Atmos to bring back to life!

Post by Wolfo »

Bought 2 x AM27C128-150DC.
Waiting for Godot! :lol:
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iss
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Re: Oric Atmos to bring back to life!

Post by iss »

You can try also my simple DiagRom which doesn't use RAM at all. Here is demo clip.
Wolfo
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Re: Oric Atmos to bring back to life!

Post by Wolfo »

I just received my 4 x 27C128 EPROM but I cannot burn them (they are used and NOT erased).
The XGecu program (I use a TL866II Plus) states that it is not necessary to erase them... since I cannot write all of them I suppose that they cannot be erased from the TL866 but they have to be erased with X-Ray, correct? if so, some hints (I have never done it)? It is sufficient to leave them at sun for awhile? If so, how much?
Thank you for your help... :-(
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Re: Oric Atmos to bring back to life!

Post by kenneth »

You can program EEPROM memories, they can be erased with the memory programmer, but UVPROM memories (with the window on the box) cannot be erased electrically, they must be illuminated for 20 minutes with a special uv tube to erase the chips , then the memory programmer will check if the memory is empty, with #FF everywhere, which will allow the file to be burned into the chip. :wink:

Image
Wolfo
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Re: Oric Atmos to bring back to life!

Post by Wolfo »

Just received today the eraser (like the one of the photo) and everything worked well.
But the Atmos is still sick.
With the EPROM I have the second screen.
WITHOUT the EPROM I have the first screen (WITHOUT = without any chip on the socket).
I really hoped to see a sign of life... :-(
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Wolfo
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Re: Oric Atmos to bring back to life!

Post by Wolfo »

Some "big" results:
° changed the eletrolitic capacitors (not a problem with them but I took the occasion to change);
° changed some broken ceramic capacitor;
° changed the RAM chips (socketed);
° socketed the 6502 and the 6522 (thanks to God they are ok);
° changed the two 74257 (socketed);
° the BIOS is also dead.
Now finally the Oric starts!!!!!!!!!
But I have issues with the keyboard... some keys do not work (C, one arrow and most of the numbers, from 1 to 6. The "space" is also strange, sometimes works some other times it do not)...
Can somebody help? What am i doing wrong? :-(
I have check the switches and they work ok (they close the connection).
The connections "arrive" to the pin of the mobo (all of them).
I have noticed that the "band" has one wire more and I connected it from the red wire on (so the opposite one is not connected).

Another (not so important): I have not found the original BIOS but "only" from 1.2 on... I am not sure the issue is related to the BIOS but I take the occasion to ask if somebody has a link to all BIOSes.

Thank you
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