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Re: Consumer electronics "war stories"
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Mark Zacharias
Mar 30, 2016, 8:03:51 AM3/30/16
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Circa 1987
Harman Kardon HK-400XM:
Three-head cassette deck.
Intermittent failure to record on one channel. Playback fine.
Customer sent to HK twice for factory service.
Twice HK replaced the record / play head assembly. Problem persisted.
On the bench, at failure mode, discovered full peak-to-peak bias at the
output of the affected channel, swamping out the audio.
Defective (intermittent coil) in bias trap. IIRC a small module.
That customer still looks me up 30 years later when he has a problem.
Couple years later, same problem on a Kenwood KX-1030. Open coil.
Over 30 years - never seen this since.
Mark Z.
Harman Kardon HK-400XM:
Three-head cassette deck.
Intermittent failure to record on one channel. Playback fine.
Customer sent to HK twice for factory service.
Twice HK replaced the record / play head assembly. Problem persisted.
On the bench, at failure mode, discovered full peak-to-peak bias at the
output of the affected channel, swamping out the audio.
Defective (intermittent coil) in bias trap. IIRC a small module.
That customer still looks me up 30 years later when he has a problem.
Couple years later, same problem on a Kenwood KX-1030. Open coil.
Over 30 years - never seen this since.
Mark Z.
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