Sharp DV-NC70U Service Manual download pdf (Page 42)

DV-NC70U/C

DV-NC72U

FLOW CHART NO.7

Does the key switch make good contact, when the

cassette tape is inserted?

Check switch contact.

Is there the function control voltage inputted at the

pins(88) and (89) of IC701?

YES

Check or replace the peripheral circuit of IC701.

YES

Key-in input is not received.

FLOW CHART NO.8

Operation is possible from the VCR, but no

operation is possible from the infrared remote

control.

Is the supply voltage of 5V fed up to pin(3) terminal

of remote control receiver?

Check AT 5V lines.

Is "L" pulse sent out from pin(1) terminal of receiver

when the infrared remote control is activated?

Replace the remote control receiver or replace the

remote control transmitter if necessary.

Is "L" pulse inputted to pin(4) of IC701?

Check line between remote control receiver thru

to pin(4) of IC701.

Replace IC701.

YES

No operation is possible from the infrared remote control.

FLOW CHART NO.9

Is "L" level applied at pin(92) of IC701?

Are start sensor shutter go to open when the

cassette tape is inserted?

Check start sensor shutter.

Does pin(92) of IC701 change from "L" to "H" level

when the cassette tape is inserted?

Check S702, R735, C753 and pin(97) of IC701.

YES

Does pin(87) of IC701 change from "H" to "L" level

when the cassette tape is inserted?.

Check between start sensor and pin(87) of IC701.

YES

Does pin(10) of AC connector become to "H" level

(4.7V) when the cassette tape is inserted?

Check between pin(92) of IC701 and pin(10) of

AC connector.

YES

Is the specified voltage (about 10V) applied at the

loading motor terminal when the cassette tape is

inserted?

Replace capstan motor unit.

YES

Replace loading motor.

A cassette tape is not take in.

FLOW CHART NO.10

Does the start sensor pulse at pin(87) of IC701

change from "L" to "H" level when the cassette

tape is loaded?

Check line start sensor and all the way up thru to

pin(87) of IC701.

Does the end sensor pulse at pin(86) of IC701

change from "L" to "H" level when the cassette

tape is loaded?

Check line end sensor and all the way up thru to

pin(86) of IC701.

Does the master cam mode shifter operate

normally when the cassette tape is loaded?

Check cam switch (A), (B) and all the way

up thru to pins(93), (94) of IC701.

Replace IC701.

YES

A cassette tape is taken in, but ejected at once.

FLOW CHART NO.11

Does the capstan motor start when the EJECT

button is pressed?

See FLOW CHART NO.13.

Does the take-up reel disk turn when the capstan

motor is running?

Check reel disk and reel drive unit.

Are pulses applied at pin(2) of IC701 when the

take-up reel disk is turning?

Check take-up reel sensor and all the

way up thru to pin(2) of IC701.

Replace cassette cam, gear, etc.

YES

Is a "H" level (about 4.7V) applied at pin(10) of AC

connector when a reel pulse has been inputted?

Check pin(92) of IC701.

YES

Is the specified voltage applied at the loading

motor terminal?

Change the capstan motor unit.

Does the loading motor run?

Replace loading motor.

YES

The cassette tape fails to eject.

FLOW CHART NO.12

Does power control(H) signal at pin(96) of IC701

change from "L" to "H" level?

Check IC701.

Does the base of Q1905 change from about 5V

to 4.5V?

Check the pin(96) of IC701 and all the way up thru

to Q1905.

Is 5V sent out of the emitter of Q1905?

Check Q1905 and the AT 5V line.

YES

No power is turned on.

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Sharp DV-NC70U Service Manual Page 42

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