Sansui 2000X static hiss

sansuilove

Active Member
Hello.
I’m enjoying this sweet receiver , but there’s a constant humm / hiss , doesn’t get affected by the volume.
1. All notorious 2sc458 were replaced with ksc1845 .
2. All caps been replaced (except the filter caps)
3. Replaced R803/R823 with metal film resistors .

Still, constant hiss.
Any help would be great.
 
Turn power off, remove pre-power jumpers and switch on again!
If hiss and hum are still there, it's the power amp section, if not there then it's in the preamp!
 
Turn power off, remove pre-power jumpers and switch on again!
If hiss and hum are still there, it's the power amp section, if not there then it's in the preamp!
It has been done, and when jumpers are out it’s silent as dead.
So It’s the power amp section .
Can the supply board be the suspect?
 
Maybe some confusion here. Removing the power from the pre-amp section isolates all but the driver amps and outputs. Now there is no noise, so the noise is before that area. So is the noise in both channels? Noise in all input selections? Might be a power supply issue?
 
I think you meant to say 'pre-amp section'. ;)
Yes it can, but my money is on the pre-amp section in this case ;)

I meant that the suspect is the power amp section because when jumpers are plugged , it has the noise.
When they are out, no noise.
I even used it as a preamp for another receiver I have (HK 330A) , and there wasn’t any noise.
 
Maybe some confusion here. Removing the power from the pre-amp section isolates all but the driver amps and outputs. Now there is no noise, so the noise is before that area. So is the noise in both channels? Noise in all input selections? Might be a power supply issue?

The noise in all inputs.
Both channels equally.
 
I meant that the suspect is the power amp section because when jumpers are plugged, it has the noise.
When they are out, no noise.
In other words you are listening to the Power Amp ONLY.

Gary Francks has it right in post #2

The jumpers being removed are the pre-amp - power amp jumpers - are they not? in other words 'signal' jumpers (not the power to the pre-amp) - therefore the noise is coming from the pre-amp!

Disconnect the pre-amp = NO noise - hence the power amp is quiet and an innocent party. :)

OR am I misunderstanding the terminology you are using?
 
Last edited:
Went ahead and checked with my old scope
This is the preamp with volume at max . Both channels clean signal (10khz)
 

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And this is the power amp board (c805/c815)
 

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