Hi, I've just brought my Apple SilenType printer back to life yesterday, hooked up on my Apple II Europlus. Amazing it still prints.
There is just one problem: it won't move the print roll. So lines are printed on top of each other. I suspect a defective electric motor on the print roll rod.
Does anybody here know what the problem could be?
@joethezombie Thank you for the suggestion! The caps are all on the back of the DayStar 040 accelerator card as shown in this photo...
I first measured voltage across each capacitor to ensure there was no voltage (caps were indeed discharged) and then performed a Continuity check across each of the tantalum capacitors using my Fluke 8845A benchtop meter. There were no shorts across any of the tantalum caps, which are the big black components in the photo above (light gray stripe marking the Positive side).
I then used my DER EE DE-5000 LCR meter to measure Capacitance and ESR, but the capacitance reading clearly shows that the caps are connected together at unknown points (I don't have a schematic) along with some of the tiny ceramic caps too, no doubt:
When measuring across either of the tantalum caps marked 10-16V (C46 & C28):
When measuring across any of the 4 tantalum caps marked 4.7-25 (C11, C29, C32, C49):
Such heart-breaking to hear! So sorry, and dang it!
You can try checking the tantalum caps on the back side for continuity. They shouldn't be shorted. So if you find one that conducts through, it's toasted and needs replacement. I don't want to suggest it will fix the entire board, but I have now repaired two PDS cards which held up the rail, stopping the computer from startup, both due to shorted tantalum caps. Ethernet cards in my case, but with some serious luck, maybe?