SHARP VT-G21
Manual de Servicio

ELECTRICAL TROUBLESHOOTING
1-1 FLOWCHART NO. 1-2

VT-G14 VT-G21

CASSETTE CONTROL TROUBLESHOOTING VCR POWER TROUBLESHOOTING

The VCR dead. (No power) A cassette tape is not taken in.

Un plug AC power cord. Replug it Is housing distored ? Fix or replace the cassette housing. a few minutes later. NO Does the start sensor cover become NO Replace the fuse. inserted ? TUNER/DEF. PWB ? YES NO IC7701 go to "L" level when Are the 12V UR 8.5V lines Check fuse resistor and transistor up to pin (2) of IC 7701. power PWB. YES YES Does pin (5) of IC7702 go to "H" level NO Check pin (12) of IC7701 and all the YES YES NO Are AT 5V GND lines Check IC7702 and UR12V line. 11V when the cassette tape is YES Is correct voltage at the loading NO loading motor. NO Check between IC7702 and the (39) of IC7701 ? Does pin (2) of IC7702 go to about NO NO Check AT 5V line, Q780 and (about 1.8V) when the cassete tape Check short in MAIN PWB. Does the start sensor pin (2) of NO Check start sensor and the way

YES

Is fuse F1701 alright in the NO open when cassette tape is Check the start sensor cover.

YES

normal MAIN PWB trouble of power circuit in the cassette tape is inserted ?

Is the AT 5V line normal ? way up to pin (5) of IC7702. is inserted ? D785.

Check poor soldering. properly connected with IC7701 inserted ?

54
NO "L" to "H" level after AC cord is Check the signal line of sys-con reset NO way up to IC7701. NO Does end sensor pulse at pin (3) of NO YES up to IC7701. YES Replace IC7701.

Is there oscillation at pins (38) and Check Replace IC7701 and / or X7701. motor terminal when the cassette tape is inserted ?

YES

Does pin (43) of IC7701 change from Check and replace the loading motor .

plugged in or/when RESET all the way up to pin (60) of IC1001. button is pressed and then released ? A cassette tape is taken in, but ejected at once.

YES FLOWCHART NO. 1-3

Check Does pin (21) of IC7701 change from power key input IC1001 to "L" to "H" level when the power Does start sensor pulse at pin (2) of NO and serial datas/clocks between IC7701 change from "L" to "H" level IC1001 and IC7701. when the cassette tape is loaded ?

Check start sensor and all the

button is pressed to turn the power on ? Is the PC 5V line normal?

YES YES end sensor all Is the PC 5V line normal ? Check Q781 and IC780 of PC9V line. IC7701 change from "L" to "H" level way up to IC7701. when the cassette tape is loaded ?

YES

Check wire harness to mechanism Do the cam switches A and B and the sensor inputs to IC7701 from NO operate normally when the cassette tape is loaded ? (at pins (100) and (1))(refer to MECHANISM flowchart) Replace the fuse.

Check cam switches and all the way

mechanism. (CAM Switches, start/end and reel sensors)