TCW
Member
I picked up non-working R-82.
This is my latest observation. These selections were made in secession one after the other after each record had been returned and magazine returned to home position. It seems to show a warmup of weak circuitry. Any information regarding component level repairs on any of the boards associated with the R-90 - R-93 class would be graciously appreciated.
Selection 101 picks up Slot 9 rather than Slot 1, next time Slot 6, then 2, & 2 again and then 1, & 1, & 1. that's got it! I then selected 102-106 and it picked them correctly in slots 2-6. Then I selected a B side, and I heard a click (B side solenoid) and the display stopped on the correct number (200), but the magazine continued to spin without end and the data LED had stopped flickering and was out. I cycled the power at the Scan Control Console and when it came to rest, I reset the Memory Unit. The data LED is lit, doing its flickering but now misses every record selected and will no longer pick up any records because it just keeps spinning. Sounds like something was not only warming up but failing and the Mech Control isn't receiving any signals to stop anywhere. I checked all the transistors and diodes in the Memory Unit. Maybe a weak cap or resistor changed value while being loaded? I would just replace all six of the fixed capacitors, but I imagine four of them would have an effect on the trimmer cap circuit that would alter the clock/data pulses (that's how it knows where to stop the Mech control).
I saw where member @omegaman set the frequency of the trimmer cap at 48 KHz on both the Memory Unit and Selector Logic unit. What I would like to know is at the Memory Unit are you supposed to measure the frequency right at chip Z704 Pin #7, Clock Send and (chassis as ground) also at Clock Send Pin#25 at Selector Logic chip Z501? Once I know where to read the frequency with my scope, I can see if that is my communication issue and I can replace the caps because they are old and i can recalibrate the frequency of the trimmer caps Memory Unit and Selector Logic unit.
Thanks for any help that can be offered to help in DIY repair.
Thanks, - Tom
This is my latest observation. These selections were made in secession one after the other after each record had been returned and magazine returned to home position. It seems to show a warmup of weak circuitry. Any information regarding component level repairs on any of the boards associated with the R-90 - R-93 class would be graciously appreciated.
Selection 101 picks up Slot 9 rather than Slot 1, next time Slot 6, then 2, & 2 again and then 1, & 1, & 1. that's got it! I then selected 102-106 and it picked them correctly in slots 2-6. Then I selected a B side, and I heard a click (B side solenoid) and the display stopped on the correct number (200), but the magazine continued to spin without end and the data LED had stopped flickering and was out. I cycled the power at the Scan Control Console and when it came to rest, I reset the Memory Unit. The data LED is lit, doing its flickering but now misses every record selected and will no longer pick up any records because it just keeps spinning. Sounds like something was not only warming up but failing and the Mech Control isn't receiving any signals to stop anywhere. I checked all the transistors and diodes in the Memory Unit. Maybe a weak cap or resistor changed value while being loaded? I would just replace all six of the fixed capacitors, but I imagine four of them would have an effect on the trimmer cap circuit that would alter the clock/data pulses (that's how it knows where to stop the Mech control).
I saw where member @omegaman set the frequency of the trimmer cap at 48 KHz on both the Memory Unit and Selector Logic unit. What I would like to know is at the Memory Unit are you supposed to measure the frequency right at chip Z704 Pin #7, Clock Send and (chassis as ground) also at Clock Send Pin#25 at Selector Logic chip Z501? Once I know where to read the frequency with my scope, I can see if that is my communication issue and I can replace the caps because they are old and i can recalibrate the frequency of the trimmer caps Memory Unit and Selector Logic unit.
Thanks for any help that can be offered to help in DIY repair.
Thanks, - Tom




