Vintage Tokai electronics question

D.K.

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Hi everybody!

Have a question to all of You who are experienced and may have a suggestion. My 1978' LS80's bridge PU has gone dead. Electronics and PU on the guitar are all original. Contact spray had been applied, to no effect. Before ripping the PCB out and going all 50's wiring and what not, I want to try and find what the problem is and if I can maybe solve it without.

So, the question is: where do I start? Potentially I can think of four main culprits:

- the PU itself
- the PCB board
- one of the pots (but would that really give that effect, too?)
- the switch

So, where would You go first and how would You check it?

Thx for any info, suggestion, etc.
 

smk506

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Do you have a multi meter? I’d start by checking the pickups themselves and then moving onto the switch, pots and board.
 

Roxy13

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You should be able to disconnect the pickup pretty easily even from the PCB if it's anything like the one Arias had during the same time period (and I think it is pretty similar from pics I've seen). And use your meter to check the pickup itself.

Worst case scenario is one bobbin probably needs rewound, but it could be something as simple as a broken solder joint on one of the little wires to the lead. Or a bad pot, jack, switch.
 

zeneffect

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Multimeter. My experience with them is the traces on the pcb were delaminating and flaked. You can fix by soldering in a wire to replace the broken trace. Visual inspection would give away bad traces. Mine is a 78 ls100, and when I went to fix it I noticed the pot values were not 500k, so I replaced and set aside.
 

Skit

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The one time I had a pickup go wonky on me it turned out to be the switch just needed a little tweeking.
 

o0mobius0o

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Good advice in this thread so far. What happens with the switch in the middle position?
 

D.K.

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Thx A LOT to everybody so far!

In the middle position the neck PU is on, just as loud as in the neck/1st position. The bridge is dead as in the bridge/third pos.
 

D.K.

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In the mid position, with bridge volume all the way to 0, any sound?
Wanted to test just that today. But decided to soak the PCB and the switch in WD40 before, just to make sure all contacts are clear and clean as can be. Let it breathe for an hour…

… and it did the trick! Everything is working just fine, not even a crack or hiss. I will need to monitore that over the following months, if this issue comes back it’s gotta be the electronics, right? But for now it’s solved.

Thanks again to everyone who answered, appreciate it!
 

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