• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

4000 constant speaker noise

A

ArizCats

New Member
Newbie here so please be gentle. Have a Sansui 4000 and based off serial number built sometime in 1970. Through hooking up to other speakers can confirm the 4000 is sending constant and consistent static feedback to the speakers, through all 3 speaker outputs (no audbile difference between outputs), even when the volume is at 0.

In comparing the feedback between my JBLs and my Klipsch KG 4's, the feedback is far more pronounced on the KG4 but sill present on the JBLs, albeit feint. So it seems to be high end feedback only if that helps in pointing me in the right direction.

I assume the issue is before the L and R speaker outputs as the sound is identical out of all 3 outputs. The sound does get louder with volume and with music consisting of clean vocals or piano it gives an almost raspy sound to things.

I do hear a light pop when the power is turned on. The buzzing/hissing is then constant from that point forward.

Thank you for your time
 
Last edited:
Register to hide this ad
You have very likely got some transistors which have gone noisy with age. I don't know if you can easily disconnect the Pre-amp from the Power amp on that model (some you can), this would help to isolate the source of the noise.

As usual with all vintage audio equipment, the switches and controls will very likely be oxidised and corroded, so these will need to be cleaned. There is a possibility that some of the noise you are hearing could be due to that.

There is a thread detailing exactly how to use DeOxit the best known switch and control cleaner for vintage hi-fi use.
Here: http://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/

There are some model 4000 experts around, perhaps one of them will chime in...
 
Thank you for the reply, very much appreciated.

Deoxit seems to be a consistent answer I have read on all posts. In my limited experince i was having trouble mentally connecting how the pots and potentiometer could be causing this feedback, but again I am novice. The inside is crazy clean and has been serviced professionally, based off the service sticker, around 7 years ago.

The receiver came with a full diagram so I may lean on some engineer friends to see what I find out.

In the meantime hopefully a 4000 expert will also have some ideas.

Thank you again
 
I haven't done work on the 4000, but I'd along with John suspect some of the signal transistors. I had a similar issue with a Sansui Eight - "white noise" in both channels, regardless of speaker or inputs - replacing all signal transistors in the pre-amp cured it. You pre-amp board F1149 has 6 x 2sc871 transistors. You may be new to Sansui's but if you have solder skills, replacing those 6 is certainly something we can guide you through. However it can be a host of other things, so lets see if a resident 4000 expert has some suggestions. Are there any difference at all in the noise from channel to channel ?, does it change at all as the amp heats up ?

P.s the speaker bump is normal for this type of amp.
 
Good info on the transistors, thank you. The white noise is the same no matter the channel (am, fm, both phonos, and aux). Warm or cold does not seem to matter.

Thank you for the reply.
 
Update on this. Gave everything a good workout over the past week. After about 30 minutes the sound lessens, never goes away though. Have triple confirmed though swapping the speakers with another receiver that it is the receiver and not something loose in the speakers.
 
Better off and cheaper to do recap and replace the transistors on yours. That board will still have to be rehabbed, so you've added the unnecessary cost of a replacement board to the recap/re-transistor. If your board is un-salvagable, then yes the board would be an alternative. Plus you have the Equalizer board you'll need to do also in all likely hood. You can recap and re transistorize both boards for about 1/2 to 2/3 the cost of the one board.
 
You must log in or register to reply here.
Back
Top Bottom