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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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This VCR was not fully erasing tapes, symptom being incomplete erasure
of chroma and hifi audio on most tapes. No voltage was found at the erase head pins when in REC. Opened it up and found R662 , 4R7 burned open. Replacement did the same, but strangely it did so from switch on - the record circuit was not energized. Not sure how significant this is - presumably this means there may be a problem with the 12v coming from the BA7755 (pin1) into choke L652? Would I be right in suspecting the amplifiier transistor Q654 (2sc3203) here are some scans of the circuit. this one is a close up of the oscillator stage, http://www.mediafire.com/?5qmy6qj6y060p2w this one is the general area, with visible lines to heads and supplies http://www.mediafire.com/?6na5n8dhgroee4c ....any thoughts appreciated. B. |
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