My beloved CA-2010 is making strange noises while powering on

bangsezmax

bangsezmax

Turntable Whisperer
Here's the scenario:

I power on my CA-2010 and wait a few seconds for the relay to click.

Once the relay clicks, the amp itself makes a strange noise, kind of a high-pitched oscillating whine. That lasts for about 10 or 15 seconds and then stops.

I've noticed that the output has some distortion for about another 30 seconds or so after the noise stops. Then all seems to be back to normal.

Once the amp is warmed up, repeating this doesn't produce the symptoms -- it only seems to be happening when it hasn't been run for a bit.

This is my favorite piece and the beating heart of my stereo. What can/should I do to make sure I don't have something seriously failing with it? Hoping one of you brilliant experts out there (Merrylander?) can point me in the right direction.

Thanks!!!
 
Should be able to locate the faulty component with a can of freeze mist.Prime suspect would be a transistor.
 
avionic said:
Should be able to locate the faulty component with a can of freeze mist.Prime suspect would be a transistor.
Click to expand...

+1 but I would have also wondered about a "lazy" cap. One that is leaking and taking a while to reach full charge.

Hmmm, I did have a Marantz once with a tired power supply. It would distort on first start up for a little while.

I have been finding a LOT of tired varistors in vintage Yamaha lately. Are the any of those jewels in the CA-2010? First thing I'd hunt down.
 
Could as well be a cold solder connection or dirty mechanical connection.
 
Okay, I did find four of these pesky VD1212 varistors in the tone control circuit -- D201, 202, 205, and 206. I can order the replacement diodes (2 in series) and do that fix. But just as a question, how likely is it that this is the cause of the strange noise? It seems to me from the symptoms that it's a power supply issue, but that's just my hunch. Could those failing varistors in the tone control circuitry (which is always set to "defeat" on my unit as it is) cause symptoms in the PS circuitry?

Is it possible that the relay itself is involved somehow?

Thanks in advance for the advice.
 
how likely is it that this is the cause of the strange noise?
Click to expand...
Unlikely..
I've noticed that the output has some distortion for about another 30 seconds or so after the noise stops
Click to expand...
One channel or both channels?

Decouple the pre-amp from the power amp with the coupler switch on the rear panel and see if it still produces the noise and distortion.
 
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avionic said:
One channel or both channels?
Click to expand...
Not sure -- it goes away pretty quickly. I think both.
avionic said:
Decouple the pre-amp from the power amp with the coupler switch on the rear panel and see if it still produces the noise and distortion.
Click to expand...
Good call -- I'll do that tomorrow AM after it hasn't been running for a while.

So if I decouple the two and there's no distortion in the preamp outs, then we're looking at something besides the preamp. I'd assume I'll get the whiny noise regardless because the amp will still turn on even if it's decoupled.
 
bangsezmax said:
Not sure -- it goes away pretty quickly. I think both.
Good call -- I'll do that tomorrow AM after it hasn't been running for a while.

So if I decouple the two and there's no distortion in the preamp outs, then we're looking at something besides the preamp. I'd assume I'll get the whiny noise regardless because the amp will still turn on even if it's decoupled.
Click to expand...

Decoupled--
If the whine disappears its a pre-amp problem. If the whine remains its a power amp problem.

If the noise is in both channels ,its a power supply problem. If the noise is in a single channel its a different problem.
 
Can you describe this "noise" a little better than whiny.As in, sounds like this or sounds like that.
 
Y'know, it almost reminds me of a slipping belt on a car engine. Not as loud of course, and there's obviously no way that it's something physically similar. But that's kinda what it sounds like -- a high pitched oscillating whine that stops after 15 seconds or so. I'll see if I can record it tomorrow and post it somehow.
 
Let's see if this works. The amp and pre-amp are de-coupled, and here's what happens:

There should be two files here, one labeled "Amp" and one labeled "Output".

Play the one labeled "Amp" first. This was recorded with a Zoom digital recorder. Come to think of it, the noise sounds more like a noisy compressor motor from a fridge. First you hear me hit the power switch, then 5 sec later the relay kicks in and you hear the bad noise and it fades away about 22 seconds after that.

Now turn down your speakers for the "Output" file. It's much louder! I have it edited so that this file starts at the same time as the one above.

Notice the distortion doesn't last as long in the left channel (about 20 seconds from the start of the music) as it does in the right (about 55 secs, or halfway through the guitar solo).

I'm thinking power supply . . .

Let me know if you can't get to the files.
 
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No telling. Squiffy cap or transistor. Like Avionic said, probably have to get in there with freeze spray.

Has it been recapped? Never a bad thing to do and sometimes you get lucky.
 
brutal said:
Has it been recapped? Never a bad thing to do and sometimes you get lucky.
Click to expand...
If this were a Sansui from the same era, I'd be thinking hard about re-capping the whole thing. But I love the sound of this unit so much that I'd rather only remove any component that's suspect as opposed to shotgunning parts.
 
bangsezmax said:
If this were a Sansui from the same era, I'd be thinking hard about re-capping the whole thing. But I love the sound of this unit so much that I'd rather only remove any component that's suspect as opposed to shotgunning parts.
Click to expand...

So you would recap a sansui but not a yamaha of the same age.That makes alot of sense:rolleyes:.I would seriously recomend a recap as well, after you find the problem.What kind of testing gear have you got?
 
Are the relays chattering as well ? Does class A sound about the same?

There are two relays one can be seen from the topside( mode switching),the other from the bottom(protect).
 
Let me put it this way -- I have HAD to get in the guts of all the Sansuis I've owned from the second half of the '70s to fix problems of some sort or another due to solder issues. Some of them multiple times. So in that way, re-capping is at the very least an effective method of retouching a lot of solder joints, and you get fresh caps to boot.

I love the sound of this unit as it is, so I'm resistant to mess with a good thing. But given its age and the amount I use it, it may be time for a re-cap. But as you said -- I want to find this issue first.

I'm very appreciative of any assistance I can get here, and I will certainly defer to people with more knowledge than me. I know a lot about fixing turntables, but not nearly as much about fixing receivers and amps.

To answer your question, I've got a Fluke DMM and an ESR meter and that's about it. Not all that confident about the accuracy of the ESR meter FWIW. No o'scope if that's what you were wondering.
 
avionic said:
Are the relays chattering as well ? Does class A sound about the same?

There are two relays one can be seen from the topside( mode switching),the other from the bottom(protect).
Click to expand...
I haven't yet tried it in class A -- been nervous to do so. I can try that tomorrow when I power it up.

As for the relays -- I'm not sure. If you heard the recording, you can hear the relay click just before the noise starts. I'm at a loss as to what could make that kind of noise that wasn't something mechanical. Like a relay. That's why I was wondering if the relay itself was having issues, arcing or something.
 
I would at least consider .. Replacing all the E-caps on the underside power supply board. As well as checking/replacing the fuseable resistors, refreshing the thermal compound on the two pass transistors and replacing the protect relay .Then thoroughly inspect/reflow(with fresh solder) the power supply PCB.
 
I opened the case yesterday to listen and see if I could pinpoint the source. It does appear to be coming from underneath where the PS board is.

Avionic, I appreciate the recommendations. They certainly sound like the right way to go. Many thanks.
 
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