sansui au-20000

More details (and punctuation) would help your cause.
Please explain? What other details do you need? It seems very clear to the problem I stated. As 4 punctuation not everyone is as smart as you!!’
 
So your tuner is misbehaving? Bad signal maybe? Better antenna? AUX input?

Tjerk, 9ZZ
 
So your tuner is misbehaving? Bad signal maybe? Better antenna? AUX input?

Tjerk, 9ZZ
Tuner in Aux input is ok works great, only on tuner input is the high pitch noise it’s like an intermittent problem. When the noise comes on the meters go crazy and I quickly turn the unit off it normally happens when amp is cold.
 
That is weird because TUNER and AUX inputs are functionally identical. If it goes berzerk, does the volume control have any effect? Does the sound go down if you lower it?

Tjerk, 9ZZ
 
That is weird because TUNER and AUX inputs are functionally identical. If it goes berzerk, does the volume control have any effect? Does the sound go down if you lower it?

no the volume has no effect the noise only comes on for a few seconds and i quickly turn it off as i'm afraid might damage something. As for the Aux input I haven't had any problems yet so if the inputs are identical that is strange. I hate those intermittent problems.
 
That's the pain with troubleshooting from a distance. With the amp on my workbench I'd prolly be able to pinpoint the issue in no time. Right now I have no clue. The volume control is behind the source selector switch. It doesn't make any sense.

Tjerk, 9ZZ
 
I had problems similar to this when I was refurbishing my AU-20000.
I’ve found a variety of issues on mine such as corrosion on the molecular style PCB connectors and pins (both sides), cracked solder joints & PCB feed throughs losing conductivity.
By that I mean - these had some double sided circuit boards and the plates holes that connect the two sides lose connectivity (primarily on the power amp boards - which get hot).

What is the serial number of your AU20000? That can help us to determine if it’s an early or later build.
 
Just fixed a restored unit.
Bad solder joints on the pins for the power regulator board.
Factory solder was iffy, restore probably lessened them when the board was pulled to work on it.

The AU-20000 is such a complicated machine there is little hope that a novice can fix it.
 
Just fixed a restored unit.
Bad solder joints on the pins for the power regulator board.
Factory solder was iffy, restore probably lessened them when the board was pulled to work on it.

The AU-20000 is such a complicated machine there is little hope that a novice can fix it.
Where the power voltage selector wires are I noticed I couldn’t tighten the screws that hold the wires there is some play there, Is that normal and could that have anything to do with the problem? Also why do I have the problem in tuner input only? Thanks
 
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Do you have any diagnostic skills?
You should start tracing the signal.
 
I had problems similar to this when I was refurbishing my AU-20000.
I’ve found a variety of issues on mine such as corrosion on the molecular style PCB connectors and pins (both sides), cracked solder joints & PCB feed throughs losing conductivity.
By that I mean - these had some double sided circuit boards and the plates holes that connect the two sides lose connectivity (primarily on the power amp boards - which get hot).

What is the serial number of your AU20000? That can help us to determine if it’s an early or later build.
When I first bought the amp it had 2 pins on the protector board fused together pin 24 and 25. since then I connected them maybe that's why that was done, those plugs go to the thermistor PR01 picture attached.
 

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