Gibson EH-100 repair advice

[Tim R. Russell]

Hi,
I recently acquired a 1939 EH-100 for a very good price which is in great condition but has been sitting in its case for the last 20years.
Upon receipt it was working perfectly.
Yesterday I gigged with it for about 3 hrs and by the end of the night it had developed a very slight buzz.
This morning I played it again and after about 30mins I noticed to buzz getting louder and the output getting quieter.
It is now very low output indeed.
I suspect one or more of the caps/resistors have failed.
This model is the one with the glue-on back and I’m looking for advice on how to fix it.
Has anyone successfully repaired this model and, if so, how did you do it?
Thanks

[Noah Miller]

It's not a failing capacitor (at least not by itself), and there are no fixed resistors in it. It could potentially be a failing potentiometer, in which case the remedy is usually to replace the pot. Or it could just be a bad solder connection somewhere.

To get in there, you need to remove the pickup and then then rest of the wiring harness through the hole. You may also have to loosen or remove the bridge to free up the ground wire.

[Tim R. Russell]

Ah, so I don’t need to remove the glued-on back to access the wiring etc?
Does anyone have a schematic or know what values of pots etc I should be using?

[Noah Miller]

The neck doesn't come off, but it's still a bit of a pain compared with the earlier screwed-on backs. The knobs come off, the jack and pots get unscrewed, then everything has to be fished out and back into place when you're done - none of which has to happen when you can just take the back off the instrument. A common problem with a lot of early electric instruments is that they weren't built for easy maintenance.

From what I can find, Gibson used 500K pots and a .05 uF cap with this pickup. There may have been some range, though - .02 uF caps are reported, as are lower-impedance pots. It was not uncommon in those days for some builders to use whatever electrical components they could get.

[Tim R. Russell]

Thanks v much for the info and advice.
Sounds like might be a bit tricky but at least it’s possible.
Do I remove the pickup simply by removing the 2 screws on the back?