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A-1000 right channel issue

Looking like input select switch
Jeff F said:
The only controls on front of amp I haven’t been able to clean are the input selectors. They are push button but on the backside there are no openings to get any cleaner in,they are sealed white rectangles soldered on input board. Is there any way to clean this type of push button selector?
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Post a photo.
 
Just tried tape1, 2 and tuner input. Same thing. Also have tried both speaker A and B with same result
 
Just realized no matter which input I’m plugged into, I can push any input button and if I turn volume up, I can faintly hear music. Example, plugged into aux on back of amp, press DAD input and turn volume up, can faintly hear music
 
Check all solder connections on that circuit board.
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Those switches will need to be disassembled to clean them %100 certain.
 
The input board on those can also have corrosive glue that may be causing the issues you're talking about. I've gone through a few A-1000s and some have nearly no glue while my current one had enough to where I needed to replace about 30 components that had been damaged.
I'd try tapping around on the input board (the one where the RCAs plug into) to see if you can get any change in sound. It's possible you may simply have a bad solder joint over there as well.
Luckily these don't seem to go Chernobyl when the glue eats things away.
 
This one really doesn’t have an over abundance of glue, just enough to have a little squeeze out. It was partly covering a few resistors but nothing really covered. What’s is really strange to me is the pulsating sound I hear in the right channel when relay clicks speakers on. The pulsating goes on for 8-10 seconds and the tempo speeds up until it stops. Hear it through speakers and headphones alike even with volume down. When I have some free time I will dive in a little deeper. I would really like to get this amp performing as it should so I can hear the excellent phono section I’ve been reading about
Jeff
 
That's an odd issue for sure. Need to do some signal tracing through the right channel to see what's up.
It could be oscillating or going through some sort of instability for a bit at startup. I'm sure it's connected to the poor sound on that channel.
Do you have a scope to watch what it's doing?

Along with the glue you will likely find a bunch of cracked solder joints as well. Some of the caps are down in value as well but I've never heard much of a difference in sound.

These are some of the nicest sounding amps you'll find IMO and an incredible value once you get the kinks of old gear worked out.
 
Unfortunately, I do not have a scope. It sounds like checking and reflowing solder joints would be a good place to start. I will also look closer at the glue on the 4 caps on that input board to rule that out. I haven’t heard any of the older, vintage Yamaha stuff but this amp would round out my system very well I think, if I can get it figured out
 
Had a little time this evening to look over circuit boards and I also cleaned rca inputs. There is a loose cement molded resistor on input board. No time to re-solder tonite. One more thing that I noticed about amp today, when turning on after being off, cooled down, it takes about 45 seconds after power button pushed in before speaker relay clicks speakers on. I then hear the pulsation then it stops and right side then will play but distorted. Hopefully will have time tomorrow to reflow solder in bad joint on resistor.
 
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Another question, should the speakers kick off when headphones are plugged in on this unit? Both play at same time on this unit, wondering if that is part of the problem.
 
Thanks omgcat, appreciate that. I am trying to rule things out on that right channel issue. Nothing glaring or obvious that I can see. Amp is very clean and like I said, not much glue. It really should work by just looking at it
 
Sorry it took so long to get back. Finally checked and no, the speakers don't shut off when you plug headphones in.

Without catastrophic failure I've only seen glue, weak capacitors and many, many cracked solder joints on units with a lot of hours one them. Otherwise the A-1000 is pretty solid.

Might be worth poking around all of the boards with a chopstick and see if you can start or stop the issue. Also, with it unplugged, give the transistors on the board a gentle wiggle. Sometimes the joints get so bad the transistors are almost falling out yet still (mostly) work fine.
That white power resistor on the BBQ board up near the volume control also likes to unsolder itself due to the heat. When I restore these I'll kink the legs of new 1/4 watt resistors so they sit up off of the board in order to increase airflow and avoid charring the board if it's still in nice shape. The big white resistor is usually the one that gets quite loose though, the small ones don't get that bad.
 

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Thanks for checking on the headphone jack. Like I said, when time permits I will reflow solder joints and probably take off caps and really clean glue off. I did notice where I did scrape some glue off of the main board for the right channel, there is a jumper by the 3 big caps that looks like it is corroded thru. I didnt notice this before. Are those jumpers any particular material or can they be made out of any type of metal? Also, how do the small white connectors from board to board come apart? Many thanks for helping out
 
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The jumpers are just tinned copper. I use clipped off component leads to replace them.
The white connectors aren't really connectors. They are soldered in pins and the white things just hang onto them.
 
The BBQ board on mine looks very good and the big white resistor is tight. That is a very good idea putting kinks in the legs of resistors for airflow. Would like to get mine running correctly then decide what to do for a refurb on it
 
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