Sansui 881 Picking up radio signal in Aux mode

[chaisu]

I picked up a Sansui 881 yesterday and I'm getting a radio signal no matter what input is selected. Turning the tuner, volume knob, or activating FM muting doesn't impact the signal, but activating Audio Muting greatly reduces the radio signal, although it is still noticeable. Detaching all input cables further reduces the signal noise, but it is still audible with my ear 3' from the tweeter.

Internet searches have brought up grounding issues with the 881 I but don't know how to troubleshoot that. I've tried moving the receiver to different locations in my apartment with no improvement.

Would appreciate any advice and troubleshooting steps I can take. I'm knew to this so please excuse me if I'm overlooking something simple.

 

[larryderouin]

Sounds like a dropped ground and therefore lack of shielding in the coax cables from the inputs, or RF leakage.

Open it up and physically check the ground from the outer casing of the RCA Jacks to the chassis 1st. Use an OHM meter to check outer casing of RCA Jack to CLEAN BRIGHT part of the chassis. Should be less than 1 ohm. Then trace out each of the cables and Ohm out the far end to the chassis. Should still be less than 1 ohm to 0 ohms. If any more than 2-3 ohms clean the ground point where the jack plate grounds to the chassis.

Check the board grounds on the TUNER BOARDS, to the chassis. Clean and repair as necessary. Also Power supply, AMP Boards(highly doubtful but do it anyway) and preamp boards.

If that doesn't do it, you may need to either re-route coax, or shield them somehow.

 

[chaisu]

Thanks for walking me through it. I'll give it a try this weekend and see what I find.

 

[chaisu]

Unfortunately, I think this is over my head. I used an OHM meter to check the outer casing of the RCA jacks to clean part of chassis and the meter kept jumping around from 2 to 90. I used contact cleaner at every grounding screw I could find and tightened them all down. Still no luck. The braided grounding wires and their connections appear to be good, but I'm not confident in my abilities. It may be time for me to pay someone else to handle this part.

My temporary solution is to keep AUDIO MUTING turned on, then my signal is crystal clear.

 

[Joseph G]

I picked up a Sansui 881 yesterday and I'm getting a radio signal no matter what input is selected. Turning the tuner, volume knob, or activating FM muting doesn't impact the signal, but activating Audio Muting greatly reduces the radio signal, although it is still noticeable. Detaching all input cables further reduces the signal noise, but it is still audible with my ear 3' from the tweeter.

Internet searches have brought up grounding issues with the 881 I but don't know how to troubleshoot that. I've tried moving the receiver to different locations in my apartment with no improvement.

Would appreciate any advice and troubleshooting steps I can take. I'm knew to this so please excuse me if I'm overlooking something simple.

 

[Joseph G]

My unit had crosstalk issues also, and I found several different problems with grounding, excessive flux and a mis-wired ground on the input jack board. To be honest, I spent many weeks chasing the ghost until I finally removed the entire input jack board, phono preamp/selector board and shielded cables. It all comes out as one piece, but it’s a job.
Try cleaning the rear selector switch board where the molex connector is soldered. For some reason Sansui used way too much flux, and on my unit it was becoming slightly conductive. The input impedance is so high that any dirt or corrosion will cause crosstalk. My unit would produce sound when the tape monitor was engaged because of a dirty tone/switch board at the tape monitor switches. It could be many things causing your problem, but the radio audio enters the rear selector switch through the molex connector on the front of the phono preamp/selector PCB. The auxiliary and phono inputs also go into this board through the soldered wires located at the bottom of the PCB. I would start there. The board can be accessed by unscrewing two screws that hold the bracket at the rear of the unit, and removing the selector extender. It can then be pulled forward, making the circuit side accessible. Good luck.