SHARP VC-A420U
Manual de Servicio

NO.12 FLOW CHART NO.14

The drum motor fails to run. No head switching pulse.

VC-A410U(B)/H810U(B) VC-A411U/H811U VC-A420U/H820U

Is the voltage more than about 2.6V NO DC given out pin(46) of IC701.
See FLOW CHART NO.13,14.

Check IC701. Is the drum motor rotating?

YES YES

Check PC 5V line. signal present on pins(66) and (65)
YES YES NO

Is the PG signal and drum FG Is the supply voltage of 5V feed to NO Are there drum PG M.M.signal at pin(3) IC706? pin(87) of IC701? of IC701, respectively? Check C753 and readjust R701. Check between pin(30) of IC701

YES

Is the voltage more than about 2.6V NO and all the way up to pin(2) of (HEAD SW. POINT control.) applied at pin(2) of IC706? IC706.

YES Replace IC701.

Is the supply voltage of feed to Check AT 12V line. pin(21) of IC706? Are the PG and drum FG YES
Could be lines between IC706
NO

NO

YES and IC701.

signals present on pins(7) and (8) of IC706? Check peripheral circuit of IC706.

Check or replace drum motor.

FLOW CHART NO.13

42
Replace IC706.
NO

The drum motor runs only for a few seconds.

Is drum PG signal given out NO Check pin(4), (5), (6) of IC706 and pin(7) of IC706? periperal circuits.

YES

Check or replace drum motor.

Is drum PG signal given out of

pin(66) of IC701?

Check line between pin(7) of IC706 NO and all the way up thru to pin(66) of IC701.

YES

Is V-H.SW.P pulse given out of NO Check IC701. pin(23) of IC701?

YES

Replace IC701.