Sansui 881 lights out

[jham55]

Sheesh it seems like this problem comes up again and again. So one stereo light was out.. I replaced it with leds and they all worked.. then flickered. I tapped the plastic case and they went on.. then every light on the unit went out. All the fuses I can see were good. There is one spot I on the plastic case that gives me caution. I will add a picture of it. The upper right top corner looks like a wire was there? I do not see any loose wires in the unit. Anyone come across this?

 

[ZR9B]

the one all the way to the left on my 881 does whatever it wants. something in my board...Ill keep an eye on yours.

 

[Warren-Oates]

I can't see much in that picture, but it's likely a baked solder joint on some of the lamp holders. A common thing for this series. First thing I would do is just reflow the joints, then retest and go from there.

 

[jham55]

all good thanks

 

[Wayne Tj]

Hi. I have the same problem, did the solder reflow fix your problem?

I had one meter lamp and one dial light out, replaced the both and now all the lights don’t work, including function indicator lamps.

I am getting 12v to the lamp board on the orange wire.

Thanks.

 

[jd3rdcoast]

Hi. I have the same problem, did the solder reflow fix your problem?

I had one meter lamp and one dial light out, replaced the both and now all the lights don’t work, including function indicator lamps.

I am getting 12v to the lamp board on the orange wire.

Thanks.

I can't see much in that picture, but it's likely a baked solder joint on some of the lamp holders. A common thing for this series. First thing I would do is just reflow the joints, then retest and go from there.

Best advice for this series right here. Pull that board and reflow all the solder joints. Have seen same problem in past on a 771.

 

[Wayne Tj]

I reflowed the board last night and no go. I put an LED bulb in for the good incandescent FM bulb and it is very-very dim - (almost) off.

There appears to be a short because when I touch the DMM leads to the FM LED bulb’s positive lead and a pad where a blue wire is attached the bulb goes to normal brightness.

The schematic that comes with the service manual that I downloaded from HFE is not that informative for the lights board (F1502).

I’ll start a deep dive on it tonight. Kind of strange that two lights were out (tuning meter and right dial lamp) and I put in three new LED dial lamp fuse type bulbs and all the lamps went out when I powered it on.

 

[jd3rdcoast]

Check Fuse F01.
Looks like voltage is fed through the selector switch S-1c (clean that real good). All the lamps are strapped across a secondary winding of transformer via B1-B4 on the power supply with Fuse F01 5A protecting them. One bulb, PL706 (Signal Meter Lamp) is tied to ground. rather than looped back to the transformer. If that bulb was shorting or perhaps have an LED in reversed it may pull it down.

Might double check your LED's to see if any (or all) need to be wired in with a + and - configuration. I apologize if I don't have the proper terminology here.

Personally, I might be prone to remove all LED's and go back and test with incandescent bulbs to confirm each bulb is working and all wiring is correct. Then proceed with LED install. Did you check with your bulb supplier that these LED's are bi-polar and whether or not you need dropping resistor before the LED's to reduce current draw? I am not an expert but have needed input from good bulb suppliers to make sure LED's are set up properly.

 

[Wayne Tj]

Thank you for the info jd3rdcoast, you gave me some ideas on where to look. All the original incandescent lamps test good, why two were out will probably lead to the cause. I did go back to troubleshooting with the original lamps.

Does anyone know if switch s-1c provides power to the lamps or provides the path to ground?

 

[jd3rdcoast]

On a 771 I rebuilt couple years ago, it was the Fuse lamp holders solder joints.

 

[TomD62]

I had issues with my 881 where the new LED's would go dim or flicker. I soldered jumper wires on the back of the board to eliminate the PCB traces and the lights remain perfectly bright every use. YMMV.