Sharp DV-NC70U Service Manual - Page 42

DV-NC70U/C DV-NC72U 42 FLOW CHART NO.7 Key-in input is not received. NO Does the key switch make good contact, when the cassette tape is inserted? YES Is there the function control voltage inputted at the pins(88) and (89) of IC701? YES Check switch contact. FLOW CHART NO.10 A cassette tape is taken in, but ejected at once. Does the start sensor pulse at pin(87) of IC701 NO change from "L" to "H" level when the cassette tape is loaded? YES Does the end sensor pulse at pin(86) of IC701 change from "L" to "H" level when the cassette NO tape is loaded? YES Does the master cam mode shifter operate NO normally when the cassette tape is loaded? Replace IC701. YES Check line start sensor and all the way up thru to pin(87) of IC701. Check line end sensor and all the way up thru to pin(86) of IC701. Check cam switch (A), (B) and all the way up thru to pins(93), (94) of IC701. Check or replace the peripheral circuit of IC701. FLOW CHART NO.8 No operation is possible from the infrared remote control. Operation is possible from the VCR, but no operation is possible from the infrared remote control. YES NO Is the supply voltage of 5V fed up to pin(3) terminal of remote control receiver? YES NO Is "L" pulse sent out from pin(1) terminal of receiver when the infrared remote control is activated? YES Is "L" pulse inputted to pin(4) of IC701? NO YES Replace IC701. FLOW CHART NO.9 A cassette tape is not take in. Is "L" level applied at pin(92) of IC701? YES NO Are start sensor shutter go to open when the cassette tape is inserted? YES Does pin(92) of IC701 change from "L" to "H" level NO when the cassette tape is inserted? YES Does pin(87) of IC701 change from "H" to "L" level NO when the cassette tape is inserted?. YES NO Does pin(10) of AC connector become to "H" level (4.7V) when the cassette tape is inserted? YES NO Is the specified voltage (about 10V) applied at the loading motor terminal when the cassette tape is inserted? YES Replace loading motor. Check AT 5V lines. Replace the remote control receiver or replace the remote control transmitter if necessary. Check line between remote control receiver thru to pin(4) of IC701. Check start sensor shutter. Check S702, R735, C753 and pin(97) of IC701. Check between start sensor and pin(87) of IC701. Check between pin(92) of IC701 and pin(10) of AC connector. Replace capstan motor unit. FLOW CHART NO.11 The cassette tape fails to eject. Does the capstan motor start when the EJECT NO button is pressed? YES NO Does the take-up reel disk turn when the capstan motor is running? YES Are pulses applied at pin(2) of IC701 when the NO take-up reel disk is turning? YES NO Is a "H" level (about 4.7V) applied at pin(10) of AC connector when a reel pulse has been inputted? YES NO Is the specified voltage applied at the loading motor terminal? YES Does the loading motor run? NO YES Replace cassette cam, gear, etc. FLOW CHART NO.12 No power is turned on. NO Does power control(H) signal at pin(96) of IC701 change from "L" to "H" level? YES Does the base of Q1905 change from about 5V NO to 4.5V? YES NO Is 5V sent out of the emitter of Q1905? See FLOW CHART NO.13. Check reel disk and reel drive unit. Check take-up reel sensor and all the way up thru to pin(2) of IC701. Check pin(92) of IC701. Change the capstan motor unit. Replace loading motor. Check IC701. Check the pin(96) of IC701 and all the way up thru to Q1905. Check Q1905 and the AT 5V line.