Sansui RA-500 question

Oneoff

Oneoff

AK Subscriber
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I’m trying to figure out if my unit is working properly.
I hook it up to my receiver tape loop I can hear a stereo signal out but the reverb effect is only on the left speaker. Is that normal?
This unit is very clean and after a service. It was performing like this before.
I also hear a little of a buzzing noise when the reverb is in full effect. But I guess it is normal with those reverb tanks.
Thank you!
 
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Is it the RA-500 or is the drop out occurring in the tape loop? Does a tape deck work through both channels?

The buzzing may be something touching the spring in the RA-500.

- Pete
 
No it’s in the unit with every type of connection, when the reverb ON button is pressed. For example also when my phone is hooked to ‘tape in’ in the unit and ‘tape out’ is connected to my receiver ‘Aux input’. I’m thinking it might be something in physical like the push button mechanism, or the rotary selector switch.
 
afaik those are stereo with 2 springs, so check & see if they're both connected in side the reverb pan?

could explain the buzz + 1ch out
 
bolero said:
afaik those are stereo with 2 springs, so check & see if they're both connected in side the reverb pan?

could explain the buzz + 1ch out
Click to expand...
Yes it was the first thing I tested. Then the entire circuit was recapped, and all the contacts cleaned.
So I’m left with something that is disconnected on the
Switches I guess.
 
Also- the schematics show stereo input and a mixed signal output of both channels into one single mono output which I guess is then mixed with the dry stereo signal. Not sure if it has something to do with that but those units are not entirely stereo output- wet signals.
 
there is a service manual around, the 500 & 700 are pretty much the same circuit

there are a few ways to hook things up, too: lots of RCA ins/outs on the back: try different options?
 
OK I checked my notes: the reverb outs are definitely stereo. The input signal is summed to mono before the reverb tank though.

Inputs are summed by the time they reach J on the schematic

K,L are stereo outs from the reverb tank, one per spring.

I have B,H as outputs to the rear switches, it's a bit confusing with those. So that may be wrong but you get the idea

"reverb amp output" I think is a good place to test?

There must be a backwards part or bad connection somewhere in your unit?

Hope that helps
 
Thank you for confirming this!
I need to trace the wet sound to the point it reduces to one channel… there was also one open fuse (one of the two 0.3A) and I replaced it but it had no effect on my issue, or anything else and that is weird.
I can’t find these two fuses on my schematics. I’m guessing they’ve added them on the later versions.
 
Additional fusing may have been market specific addition, as was required for units sold in the US (by UL listing requirement) and Canada (where CSA dictated such).
 
I missed the part about 1ch not working ever since you got it & before restoration

So probably a bad component? And if a fuse was blown there's a clue
 
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I checked each and every transistor and diode , replaced all the caps, and cleaned all the contacts.
Maybe this weekend I’ll have some time to dig deeper.
 
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