Hi
Thank you for letting join.
I have just bought an Oric 1 (had 1 back in the early 80s) I have bought it from an auction house, but after turning it on (with a modern power supply) it’s got scrambled graphics and lines on screen, could someone point me in the right direction. I have repaired BBC micro’s but I only have basic equipment and I am just a novice .
Please see images.
Any help would be much appreciated, as I would love to see this running again.
Oric 1 issues
Re: Oric 1 issues
Hi,
first, looks like the ULA is working because we can clearly see we have 40 columns of "characters", and possibly the 27ish lines as well.
That's good, it's the only specific Oric chip, and it's in charge of the display, but also generating the frequencies used by the other chips as well as doing the memory refresh.
A common issue with the Oric is people using the wrong PSU, with the incorrect polarity, which generally results in frying RAM chips (a variant of that is to plug the power connector by mistake on the expansion bus when trying to reboot, which results in the same type of problem, so I suggest putting something on the connector to avoid that.
First diagnostic would be to open the machine, let it run, and then try to see if any of the RAM chips are warmer than the others, that's often been suggested as a way to test things.
If you have an eprom programmer, using a diagnostic ROM can be helpful as well.
first, looks like the ULA is working because we can clearly see we have 40 columns of "characters", and possibly the 27ish lines as well.
That's good, it's the only specific Oric chip, and it's in charge of the display, but also generating the frequencies used by the other chips as well as doing the memory refresh.
A common issue with the Oric is people using the wrong PSU, with the incorrect polarity, which generally results in frying RAM chips (a variant of that is to plug the power connector by mistake on the expansion bus when trying to reboot, which results in the same type of problem, so I suggest putting something on the connector to avoid that.
First diagnostic would be to open the machine, let it run, and then try to see if any of the RAM chips are warmer than the others, that's often been suggested as a way to test things.
If you have an eprom programmer, using a diagnostic ROM can be helpful as well.
Re: Oric 1 issues
Hi
Thank you for your swift reply, I will open it up and check ram for heat, I will post back after checking.
Thank you.
Thank you for your swift reply, I will open it up and check ram for heat, I will post back after checking.
Thank you.
.Re: Oric 1 issues
Right I have had oric 1 apart and the only 2 chips that are warmer than the rest is C5 and C6.
Please see image below, all looks very clean and tidy so far.
Please see image below, all looks very clean and tidy so far.
Re: Oric 1 issues
Thank you, I have been searching and will continue to do so as its in such good order, not a mark on it, so would love to get it running again.
Re: Oric 1 issues
I would also suggest to get the service manual:
https://library.defence-force.org/index ... ch=service
Regarding the diagnostic cartridge and rom, you can find them on Mike Brown site:
http://oric.signal11.org.uk/html/diagrom.htm
https://library.defence-force.org/index ... ch=service
Regarding the diagnostic cartridge and rom, you can find them on Mike Brown site:
http://oric.signal11.org.uk/html/diagrom.htm
Re: Oric 1 issues
Hi Every one
Sorry for the delay, I was waiting to borrow a thermal imaging camera to show temperature of chips on the Oric 1.
this is after 5 minutes .
I have also took some minor readings with my multimeter. Power supply output 10 volts, Oric input 9v, bridge rectifier converts it to 5 volts, common is just over 0.
Sorry for the delay, I was waiting to borrow a thermal imaging camera to show temperature of chips on the Oric 1.
this is after 5 minutes .
I have also took some minor readings with my multimeter. Power supply output 10 volts, Oric input 9v, bridge rectifier converts it to 5 volts, common is just over 0.
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