I am trying to service my 410 cassette drive. Made in Taiwan. Put in new belts, FF and rewind work. Following test points in the service manual, trying to confirm the health of the two ICs, one CA3046 transistor array and other the LM324N opamp, while I have it open.
With the unit plugged in, with no tape, play engaged, not hooked up to my 400 computer, should I be seeing measurements on the pins of the ICs? Schematic shows +5V test point next to R130, i have nothing. Tried engaging S101 as well. Not getting any readings in static mode either.
I am using pin 4 of IO cable as ground reference. i soldered a wire to that pad so I can clip to ground with VMM.
got nothing on V+ of the opamp.
Do I need a cassette in to get test point readings? Any advise would be appreciated.