Pioneer SX-939 Lights not working.

[prose116]

Hi all,
I picked up a SX-939 a few weeks ago for $50. from a guy that had it in his garage for 15 + years.
I cleaned it up and recapped all the boards. I put new LEDs in and all lights work except for the function lights AM, FM, Phono 1, Phono 2, Mic, and Aux. I tried following the schematic , but I am not very good at understanding them yet.
Everything else works perfectly.
The lights never worked even before I did anything to it.
Any help would be appreciated.
Thank You.

 

[markthefixer]

does the stereo indicator lamp work?
That's the same power feed as the AM, FM, P1,P2,MIC & AUX lamps.
They are the only lamps run on DC, all the rest are run off of 2 AC windings from the transformer (blue/violet to black ground)
of which either the blue or the violet wire are selected by 3 sections of the switch run in parallel (AWS-068 pins 1,4,5)..

This all tracks back to the AWS-068 BRIGHT/DIM switch which tends to get burned up over time.
paradoxically this is the LESS abused #4 set of contacts (AWS-068 pins 2,3) on that switch.

And I DO mean burned up.

 

[prose116]

does the stereo indicator lamp work?
That's the same power feed as the AM, FM, P1,P2,MIC & AUX lamps.
They are the only lamps run on DC, all the rest are run off of 2 AC windings from the transformer (blue/violet to black ground)
of which either the blue or the violet wire are selected by 3 sections of the switch run in parallel (AWS-068 pins 1,4,5)..

This all tracks back to the AWS-068 BRIGHT/DIM switch which tends to get burned up over time.
paradoxically this is the LESS abused #4 set of contacts (AWS-068 pins 2,3) on that switch.

And I DO mean burned up.

Stereo light works fine.

 

[markthefixer]

The DC is supplied in common to all the named lamps.
To light a lamp, the lamp is grounded.

BOTH sides of an unlit lamp should show that DC voltage, which will indicate a readiness to light.
But you HAVE to be SURE of which side of the lamp you are on, IF you contemplate grounding a lamp to see if it lights.
The WRONG side will just short out the power.

The way the lamp circuits are DRAWN by a draftsman way way back my not accurately represent what was actually done on the production line.

So just see if the lamp voltages are present at the connections to the switch board AWS-069 pins 1,2,3,46,47,48
Be SURE AWS-069 pin 45 has a GOOD ground!!

 

[prose116]

Sorry for slow reply, I have not had a chance to work on it yet, I will get to it on Saturday and will let you know.
Thank You for your help

 

[Neil1988]

Hi, curious, I just picked up an SX-939 and all the lights are out but the Stereo lamp comes on. It plays fine, just no lights, I replaced all the fuses as well, still no luck. Any thoughts? Is there another fuse I am missing? I replaced the 6 on the power board, and by the way, the originals were fine. Any suggestions would be appreciated.

 

[prose116]

Do you measure any voltage on the above referenced pins?

Have they been replaced?
make sure they are not reversed ie, neg to pos and pos to neg especially if the are LEDs