SX-650 Very Low Output on One Channel - All sources except tuner

Or-- your tuning into a highly compressed FM radio station, thus making any other signal source appear weak !!

Hey !! With the heavy handed compression used on OTA transmissions, a OTA FM signal as a over all sensitivity reference against other inputs would be questionable IMHO/E !!
A specially after cleaning/spraying out the function switch, and checking out the other line level inputs with a known reference source, whether a CD player, audio signal generator`s output set to the equipment`s input sensitivity specifications with a scope, and or ACVM connected to the speaker outputs, or tape outputs to get some idea if there is really a circuit issue.

Just a thought..

Good luck.
Much kind regards, OKB
 
As I noted above, output is fine on both channels when using the tuner. Output is dramatically reduced on right channel with other inputs.
 
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Success! I took off the front chassis plate again and used a stiff hobby paintbrush and deoxit to clean the selector switch contact points yet again. I then desoldered and resoldered all of the switch connections. Put things back together and sounds great; of course, since I didn't power it up until I had done the deep clean AND the resoldering, we'll never know which it was!

I had already addressed a problem in the phono section, and this evening I went ahead and recapped it and the tone board (including the blue sanyo aluminum caps).

Now all I have to do is prep, prime and paint the cabinet, and it will be good to go. The authentic woodgrain vinyl had some bad spots, so I peeled it off. I've done this on several of the lower end x50 and x80 receivers over the years, spraying them semi-gloss black and finishing with clear coat. I really like the way they look when done this way.

Thanks very much to all who took the time to respond to this thread, especially avionic, whose direction clearly narrowed it down to the selector switch.
 
This whole endeavor will be useless without photos of the finished product (I'd be interested to see the results of the refinish).
 
This whole endeavor will be useless without photos of the finished product (I'd be interested to see the results of the refinish).

I may not get around to painting the cabinet for a little while...I have it and one from an SX-780 to do, and I've found that taking the time to set up a little spray booth in the garage provides much better results (keeps the dust off while the paint is setting up).

In the meanwhile, here are a couple of pics of SX receivers I've done in the past:

SX780g.jpg IMG_0080.JPG SX750.JPG
 
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Thanks. I like the look, contrasting the aluminum face with black. It's crisp.

Me too. When I used this approach for the first time, I wasn't quite sure how it would turn out. But I too like the look...crisp is a good adjective. The black makes the faceplate really pop.
 
Think again. This time review the schematic.:thumbsup:

I always am amused when its just bad contacts. Reassuring though.

I once repaired an SX-737 that had only one channel out from the tuner and only the tuner. Turns out someone had desoldered a capacitor in the signal path and forgot to re solder it.
 
I may not get around to painting the cabinet for a little while...I have it and one from an SX-780 to do, and I've found that taking the time to set up a little spray booth in the garage provides much better results (keeps the dust off while the paint is setting up).

In the meanwhile, here are a couple of pics of SX receivers I've done in the past:

View attachment 1317027 View attachment 1317030 View attachment 1317033

When I first read the description of what you were doing I thought "no, no no no no... noooooo" (I do love my real wood 636 cover) but I have to admit after looking at the pictures for a bit, it looks great.. almost good enough that I wouldn't mind owning one of these later silver-faced, full of levers, instead of buttons, receivers if it looked like that. :beerchug:
 
When I first read the description of what you were doing I thought "no, no no no no... noooooo" (I do love my real wood 636 cover) but I have to admit after looking at the pictures for a bit, it looks great.. almost good enough that I wouldn't mind owning one of these later silver-faced, full of levers, instead of buttons, receivers if it looked like that. :beerchug:

If it had been a wood veneer, I would have repaired it. Not much you can do with that vinyl/plastic stuff they used.

I have veneered a 750, and it came out quite nicely. Good experience, but not cost effective...took quite a bit of time.

Did you take the vinyl off of your 636 and do the wood veneer yourself, or did you have it done?
 
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I always am amused when its just bad contacts. Reassuring though.

I once repaired an SX-737 that had only one channel out from the tuner and only the tuner. Turns out someone had desoldered a capacitor in the signal path and forgot to re solder it.

Glad I could amuse you.

If I had to bet, my money would be on a solder joint as the cause of the problem, given that the switch contacts showed no signs of serious oxidation, and given that they had been cleaned/"deoxit-ed" pretty well already.

The switch assembly is board mounted, and years of use put a lot of stress on those joints.
 
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Glad I could amuse you.

If I had to bet, my money would be on a solder joint as the cause of the problem, given that the switch contacts showed no signs of serious oxidation, and given that they had been cleaned/"deoxit-ed" pretty well already.

The switch assembly is board mounted, and years of use put a lot of stress on those joints.
Ah! Well it's good that you got it running!
 
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