Hi,
I have a beat up TFTC whose backlight never lit up. I'm ready to look into it - I checked continuity from the backbox lights to the boards and everything looks good (it goes straight to the Power Supply).
I checked the Test Points on there. +5V is +5V sharp, +12 is about +11 and -12 is about -14.

When I look at the pins that should power the backglass, I get somewhere between 0 and 1V AC, where I should get 6.3V AC.

I looked at the schematics but I don't understand what's going on (included pics) - it does look like it goes through a relay. Maybe I should try to short that relay and see what happens? I don't understand how that 6.3V gets generated, not from looking at the schematics anyway - I haven't removed the PS yet, I wanted to see if I can narrow it down further before I have to do that.

Thanks
Phil

PSSchematic1.JPG

PSSchematic2.JPG

Oh,
that would make sense. So that's why the schematic shows pretty much straight wiring - the PPB feeds that 6.3V then?

I'll look into that after supper, thanks for the tip.

Yep,
you guys are probably right.

The circuit is simply that the PS sends power to the PCB just to go through fuses, then back to the PS and on to the GI.
The connector pins that receive power for the backbox are pretty much toasted. Although continuity checks out, I get full voltage on the PS, but it goes down to below 1V on the connector.

I had ordered a bunch of connectors exactly for this kind of thing, but I can't find them anymore...
I'll order some and let you guys know how it turns out, but it definitely looks like that's the problem.

Thanks for the help.
Phil

Yep,
that did the trick. The connector pins almost fell apart when I took off the connector.
Thanks a lot guys.

I was looking at the light bulb circuit behind the backboard panel and I was wondering how come it looked like somebody had soldered the two independent circuits together.
I guess the first pin went out, shutting down half the backglass, and the wise but lazy guy figured he'd just hook the two together, which would have put double the stress on the second pin until it burnt out too.

Phil