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I need help diagnosing one dead channel - Sansui SD3030

Joined
Nov 29, 2017
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#1
Anyone have experience with diagnosing a Sansui SD-3030 quad player? I'm not getting signal from the front left channel. Using a quad tape, in forward play, I get signal on the front right, but not front left. In 4 channel mode, the rear two channels sound like they are playing backwards. In reverse play, all four channels work perfectly.

Heads and pots were cleaned (alcohol and deoxit, respectively).

I can't locate a service manual anywhere, and the SD-5050 looks sufficiently different that its service manual isn't much use.

I've got a DMM, and an oscilloscope (although I'm not great at using the oscilloscope yet) for diagnostics. Besides a signal generator (which I assume I can get an app for). what else do I need to re-align the heads?

Thanks,

Mike

Ampex AX-300
Sansui SD-3030
Akai X200D
Fostex R8
 

quadsearcher

700 Club - QQ All Star
Joined
Nov 8, 2010
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#2
If you hear something backwards while other tracks are playing forward, it must not be a quadraphonic tape. Hearing two channels backward at the same time as two (or one) forward indicates it is a stereo tape. Quadraphonic tapes are recorded with four channels in the same direction. No malfunction of the unit can change the direction of tracks on the prerecorded tape.
 

quadsearcher

700 Club - QQ All Star
Joined
Nov 8, 2010
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#3
Also keep in mind that if a groove is worn into the heads where the tape travels, the heads cannot be adjusted without damaging tapes. If somebody has already changed their position, look carefully at the tape path when threaded, with a good light, to make sure it isn't already creasing the edge. Been there, done that, took a while to get them back where they had been.