Yamaha CA-600 - Right channel drop, but AC signal test is ok?

AintBeenDead

Active Member
Hopefully someone can help me here. I have a CA-600. I really want to use it as a pre-amp. However, I get a significant signal drop in the right channel. And on any input. It does this in both, coupled, and un-coupled state.

In very good shape, was thoroughly cleaned, and deOx'd. Both bias, and mid-point dialed in smoothly, and are both steady as a rock after multiple passes. As well, I ran a 1000hz test tone into the AUX (both), turned up to 5v. and I get just above that (5.3) in the R channel (bad one).

I'm baffled. If it's in the pre-amp stage, why would I get a pretty even signal at the out puts in both modes?

Suggestions much appreciated.
 
Hopefully someone can help me here. I have a CA-600. I really want to use it as a pre-amp. However, I get a significant signal drop in the right channel. And on any input. It does this in both, coupled, and un-coupled state.

In very good shape, was thoroughly cleaned, and deOx'd. Both bias, and mid-point dialed in smoothly, and are both steady as a rock after multiple passes. As well, I ran a 1000hz test tone into the AUX (both), turned up to 5v. and I get just above that (5.3) in the R channel (bad one).

I'm baffled. If it's in the pre-amp stage, why would I get a pretty even signal at the out puts in both modes?

Suggestions much appreciated.
Have you tried cleaning the switches and controls yet?
 
Have you tried cleaning the switches and controls yet?

Done that everywhere I can think of. They're all very easy to get too. And I scoured the phone jack as it was very oxidized. All the pots, and switches got a good spray, and woggle.
 
I get a significant signal drop in the right channel.
Lightly tap on the protect relay. See if it causes the right channel to drop in and out.
 
Tapping the relay with an input going through made no difference. I also noticed with the volume completely down, it still produces sound in the right, dead in the left, and that of course continues as volume is increased. it's also pretty scratchy in the volume pot when first turned up in either channel. But I've hit that pot twice now (will try one more).

Also, if it makes a difference. I just changed the bulb, as it was toast. I'm using a 14v 80mA that I had left over form one of my other Yammies. It was from djwojo, and said it was okay to use in 12v application. Bias was re-trimmed, and and both channels sit at about 48mv, mid-point is 3-4mv in each channel. And I still get all of a .20mv difference in the L/R on AC signal test, with the left being slightly lower (this being the louder channel though).
 
Also, I know you told me before that at least with offset, a +/- value on the read out didn't matter, and I'm assuming the same on bias. One channel reads +, one channel reads -, but both in the same number range.

Does this matter?
 
Also, I know you told me before that at least with offset, a +/- value on the read out didn't matter, and I'm assuming the same on bias. One channel reads +, one channel reads -, but both in the same number range.

Does this matter?

No. Doesn't matter.
 
If it helps anyone, help me here. This is what I did/found today. Pulled the function sheet, re-flowed all the solders on it, as well as all the solders on the vol/bal/loudness sheet, and everything they attach to. And re-pasted the outputs for good measure (unrelated, but who knows). As well, hit every connector with deOx, and the air duster.

One thing I have found is that with the audio muting engaged I get pretty even output, at least with very little test speakers. I'll have to hook it to the main rig to see if that holds true. But I triple cleaned the heck out of the switch, and wiggling in anyway makes no difference in output level.

Could anyone say if there is some specific components that feed into the switch that could be an issue? Also, if I need a new vol/bal pot, where would a guy come across one of these new?...

UPDATE: audio muting was a fluke, still the same drop in the right.
 

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where would a guy come across one of these new?...
Slim to nil chance of finding a new one.

On these CA models I have to disassemble and clean the Mode,Function and tape monitor switches to get them working properly. This means removing them from the board and disassembling to clean them.
 
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Slim to nil chance of finding a new one.

On these CA models I have to disassemble and clean the Mode,Function and tape monitor switches to get them working properly. This means removing them from the board and disassembling to clean them.


Do you think those switches being not clean enough would cause this problem?
 
Do you think those switches being not clean enough would cause this problem?



A very good chance... Its impossible to get the deoxit where it will do any good without tearing them apart.
 
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A very good chance... Its impossible to get the deoxit where it will do any good without tearing them apart.

Well, I'd definitely like to try. Can you give me a basic method?

Eraser, fine wire brush? I'd think being gentle would be key, and a brush would damage the switch. or would just some Q-tips and deOx in the case work?
 
Well, I realized about 10 minutes in, that without some wick (out), I wasn't getting that switch off. I did manage to pop off some traces with the solder sucker :(

Anyway, got the traces fixed, pulled the vol/bal pot, sprayed and air dustered the living heck out of it, put it back together, problem worse. I"m thinking it's that pot. In addition to a bigger gap in output, it was even scratchier than before. I either got dead spots, or some are just getting that much cleaner than others. Seems so anyway. And I have no idea how to completely break down that double-double stack pot.

So, avionic, or anyone; Got a good clean vol/bal pot (100 over 250k) for sale?
 
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Well, I realized about 10 minutes in, that without some wick (out), I was getting that switch off. I did manage to get pop off some traces with the solder sucker :(

Anyway, got the traces fixed, pulled the vol/bal pot, sprayed and air dustered the living heck out of it, put it back together, problem worse. I"m thinking it's that pot. In addition to a bigger gap in output, it was even scratchier than before. I either got dead spots, or some are just getting that much cleaner than others. Seems so anyway. And I have no idea how to completely breaking down that double-double stack pot.

So, avionic, or anyone; Got a good clean vol/bal pot (100 over 250k) for sale?

ebay
 
YAMAHA CA600 volume /bal /pot

So, avionic, or anyone; Got a good clean vol/bal pot (100 over 250k) for sale?

Avionic says : EBAY

" There is another hope "
 
So, avionic, or anyone; Got a good clean vol/bal pot (100 over 250k) for sale?

Avionic says : EBAY

" There is another hope "

Such is the life of a Yamaha fan (or any I suppose). I got two great pieces, one needs at least a pot, the other a power switch. Might live my whole life, and never find either. Unless it's from tearing down another unit :(
 
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