Yamaha KX-930 Playback not Recording Issue

[Radster]

Strange problem with one of my newer decks. As usual Yamaha has done a great job of creating a clear. easy to read circuit board with clearly defined areas for all the functions.

However...recording works fine both channels. On playback only the right channel works. The left channel meter shows -4 constantly and no sound is detected coming from that channel. When I rotate the PB pot for that side the bar goes up and down in sync with the rotation but no sound still arrives.

With the clean interior and newer parts that is not that much to clean contacts on.

Any ideas? Is there a channel contact or switch somewhere in the mech?

Thanks

Konrad

[Jay Pemberton]

Sounds like at least a bad op amp in the playback section....start tracing backwards from that level pot. Is that DC or something ultrasonic causing that steady level?

[Scorpion8]

First thing I'd try is (a) is it the same on headphones, and (b) clean the heads. And then clean them again. And again since you're at the machine. Especially if this is a "sudden" problem then it's likely there's just a piece of tape shed in the head gap. Do the easy stuff first before we chase signal paths.

[Jay Pemberton]

First thing I'd try is (a) is it the same on headphones, and (b) clean the heads. And then clean them again. And again since you're at the machine. Especially if this is a "sudden" problem then it's likely there's just a piece of tape shed in the head gap. Do the easy stuff first before we chase signal paths.

The left channel meter shows -4 constantly and no sound is detected<snip>

How could that be caused by a dirty head?!

[Scorpion8]

I've seen it happen, and at worst he loses 5 minutes and ends up with clean heads. Always do the easy things and tests first.

[Radster]

Used contact cleaner on all the pots and switches. Also cleaned the head several times. As a deck it was pretty spotless to begin with. I have to agree with the ultrasonic thing since it shows alot of output and nothing arrives at the headphone or output jack.

I was also wondering if it could be a cold solder joint somewhere on the circuit board attached to the head or the main board. Would the head ouput show up on a multimeter? Both channels are labeled pretty well so the connections are obvious.

Thanks

Konrad

[Scorpion8]

Sounds like (bad pun) you've verified that it's somewhere in the circuitry. Time to probe along and find the bad component or bad solder joint.