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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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Car Cassette Deck-1 Channel Dead
Realistic Am/Fm Auto-Reverse Tape Deck
The tuner and output/line level amps are ok on both channels. The cassette deck left channel is very weak-right channel OK. I adjusted the head for best freq. response but still no left channel. Auto reverse decks use 4 channel head and switch the channel pairs for rev. So, it can't be 1 dead channel in the playback head, as the left channel is dead both directions. Ditto for the phase switch. Preamp? Or am I missing something? JR |
#2
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Look for an open or high esr cap mabe between the head and pre-amp
circuits. "JR NORTH" wrote in message ... Realistic Am/Fm Auto-Reverse Tape Deck The tuner and output/line level amps are ok on both channels. The cassette deck left channel is very weak-right channel OK. I adjusted the head for best freq. response but still no left channel. Auto reverse decks use 4 channel head and switch the channel pairs for rev. So, it can't be 1 dead channel in the playback head, as the left channel is dead both directions. Ditto for the phase switch. Preamp? Or am I missing something? JR |
#3
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"JR NORTH" wrote in message ... Realistic Am/Fm Auto-Reverse Tape Deck The tuner and output/line level amps are ok on both channels. The cassette deck left channel is very weak-right channel OK. I adjusted the head for best freq. response but still no left channel. Auto reverse decks use 4 channel head and switch the channel pairs for rev. So, it can't be 1 dead channel in the playback head, as the left channel is dead both directions. Ditto for the phase switch. Preamp? Or am I missing something? JR Bad caps are often the cause of weak or distorted channels. You could use an ESR meter and start checkin those electrolytics down the line. ESR isn't the last word in capacitor analysis, but it does help find bad ones in many cases. As a last resort, substitute the electrolytics in the bad channel one by one. Of course, after you've fixed the actual problem, you may find output still isn't up to par, as you've misaligned the head azimuth. Easy enough to correct for best APPARENT sound, but doing a proper job involves an alignment tape and a scope with a vector (X-Y) mode -- you have to adjust not only for amplitude but also zero phase shift between the two channels. |
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On Mon, 16 Aug 2004 17:00:26 -0700, JR NORTH
put finger to keyboard and composed: Realistic Am/Fm Auto-Reverse Tape Deck The tuner and output/line level amps are ok on both channels. The cassette deck left channel is very weak-right channel OK. I adjusted the head for best freq. response but still no left channel. Auto reverse decks use 4 channel head and switch the channel pairs for rev. So, it can't be 1 dead channel in the playback head, as the left channel is dead both directions. Ditto for the phase switch. Preamp? Or am I missing something? JR I had a similar problem with a Fujitsu Ten player. IIRC, the problem was either a broken flex cable, or a dirty switch. - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
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