Fixing input selector on old Yamaha amp

[JulesBadass]

Any advice on the above would be appreciated.

The input selctor is a) noisey in terms of static when moving it, and b) I have to delicately fiddle with it to make the sound come out of both channels clearly - even when I've got it about right, im not convinced it's 100%.

I'm handy with a screwdriver and happy to service it. Question is, does it sound like something which just needs a clean, or does it sound knackered? If the latter, where might be a good place to source a new one?

Thanks in advance.

 

[Vladimir]

Any advice on the above would be appreciated.

The input selctor is a) noisey in terms of static when moving it, and b) I have to delicately fiddle with it to make the sound come out of both channels clearly - even when I've got it about right, im not convinced it's 100%.

I'm handy with a screwdriver and happy to service it. Question is, does it sound like something which just needs a clean, or does it sound knackered? If the latter, where might be a good place to source a new one?

Thanks in advance.

Hey Mr. Badass.

It's a very easy fix. You just need a electronics contact cleaner spray and you just squirt in all pots and switches inside the amp, work them a bit to spread the chemical, repeat like that 3 times and you will have excellent sound. Do not use general use WD40, it must be a specialized for electronics (doesn't have oil in it). You have electronic contact cleaners at Maplins.

Watch a tutorial on youtube how to do this and be carefull not to touch the big caps and the transformer (can hold high voltage even unplugged for days). Have the amp unpluged from the wall socket and be frugal with the spray, spray only inside the pots and switches with the straw nozzle, not like a deodorant all over. You may also spray the RCA input plugs and the speaker terminals to give them a good cleaning.

https://www.youtube.com/watch?v=njwi-GwJBzc

https://www.youtube.com/watch?v=kwDBWO0izQo

If you also have a multimeter, its good to check the DC offset voltage out of the speaker terminals while the amp is turned on, with no music playing with it and volume knob turned down. It should measure under 50mV for each channel. The lower the better.

 

[JulesBadass]

Many thanks - great.

Good tip on the DC offset too, will see what it reads.

Right - will source some contact cleaner then!

Cheers.

 

[Tannoyed]

Try Servisol contact spray, have used it for 30 years. CPC is a good place to look. Smokers suffer from this problem a lot! Residues build up all over the potentiometer tracks. Age and dampness do the same. Pots usually have a small hole in the body (a stamped out section) so spray it in there carefully, leave it for a few seconds then operate the contol over the full range of its travel several times. This stuff will improve noisy input selector switches too. The controls will feel less stiff afterwards but this is normal.

Dont adjust any presets on the pcb without first noting their positions. These may be level settings but they could affect biasing of semiconductors and haphazard twiddling is a recipe for disaster. The front panel controls can be adjusted at will obviously! If it's not on the front panel, be careful.