Mailliw
Well-known member
Hello,
I've been picking at this machine for a while, but recently I re-soldered all the molex connector pins and re-socketed/re-chipped the analog torque board. It *seems* to have fixed a torque problem with the supply reel, but now I have a problem with the take-up reel spinning fast on idle.
I checked the DC offset for the reel motors (as per the maintenance manual) and I measured +5.5V on the take-up reel (TP1) and +2.5V on the supply reel (TP2). The manual says they should both be +/- 0.1V or less. The 10K trimmers are having no effect on the DC offset. I tried the other adjustments (idle, full reel, empty reel) but none of them have any significant effect on the DC offset.
I did hours upon hours of re-soldering to restore some consistency to this machine, meaning my soldering iron touched a lot of these circuits. The problem could be anywhere.
On the bright side, the problem does affect both reel motors (the take-up reel a little more so).
Schematic:
In order for the schematic to be legible, it is 3000 pixels wide!
Any help is appreciated. :grin:
I've been picking at this machine for a while, but recently I re-soldered all the molex connector pins and re-socketed/re-chipped the analog torque board. It *seems* to have fixed a torque problem with the supply reel, but now I have a problem with the take-up reel spinning fast on idle.
I checked the DC offset for the reel motors (as per the maintenance manual) and I measured +5.5V on the take-up reel (TP1) and +2.5V on the supply reel (TP2). The manual says they should both be +/- 0.1V or less. The 10K trimmers are having no effect on the DC offset. I tried the other adjustments (idle, full reel, empty reel) but none of them have any significant effect on the DC offset.
I did hours upon hours of re-soldering to restore some consistency to this machine, meaning my soldering iron touched a lot of these circuits. The problem could be anywhere.
On the bright side, the problem does affect both reel motors (the take-up reel a little more so).
Schematic:
In order for the schematic to be legible, it is 3000 pixels wide!
Any help is appreciated. :grin: