Post by Vyper68 on May 20, 2019 8:09:37 GMT
Some of us here are big Oric fans as well as Atari and it's no secret both 8bitbaz and I are among them. I was gifted an Oric-1 by 8bitbaz originally sent for repair but gifted ( Thanks Baz ) after it was a seemingly urepairable Oric-1 due to someone in it's past had plugged the 9V PSU into the expansion connector and sent 9V all through the board and basically fried every IC on the PCB. So we are talking ALL logic IC's, ALL RAM, AY Sound Chip, CPU, VIA, ULA, ROM, PROM, TTL Crystals, so only the PCB, capacitors and resistors were usable.
So I when I tried to repair it I originally thought it may be a damaged 7905 Voltage Regulator or faulty RAM or ULA so I tried these and nothing worked so it was becoming obvious it was going to be expensive to fix so it was relegated to a part-time project and gradually over time parts were sourced and replaced and the Oric tested. Eventually it had got to the point I had repaired the all the IC's on the main PCB, the 12 Mhz Clock, three BC184 transistors, tested the Oric and still got nowhere. I decided not to bother with the PROM or 8 Mhz clock as they are only used for the UHF Modulator and it would be used only with an RGB SCART lead so to keep costs down I didn't look to change that ( maybe I should now it's working ) I had bought a 65c02 CPU but it still didn't work so I refitted it with pin 1 disconnected and pins 2 and 36 connected as per the thread on DF and then it would boot to Black & White vertical bars so I thought the EPROM I had burned was suspect. I burned a diagnostic ROM designed by MikeB on DefenceForce and tested the PCB again and finally got somewhere the RAM passed as did the ULA it was when it tried to test the VIA it would fail. So I plugged in the Oric 1.1B EPROM again and it would almost boot but stick at thin Black vertical lines on a White background so it hanging on something. So I replaced the 6522 with another I had and powered on to be greeted with the Oric BASIC welcome screen. Sadly the keyboard did not work at that point and it turned out to be the 4051BE IC on the keyboard PCB once that was replaced I had a working Oric-1.
It has turned out to be a mammoth project and sadly an expensive one too. It became a money pit but I was determined to get it working again and to have finally succeeded was very satisfying. So a steep learning curve on Oric repairs but now I am more confident that I could take on another one in the future.