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Ground hum in an old Wurly 140B


OldTuna

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You will have to open up the board and start checking for loose wire ground connections. That is usually the problem with getting "hum" on those older Wurlies. I had a couple of them and each time I fixed it by running down loose connections. Make sure too that you have a three prong grounded AC cord. That sometimes too can be the problem. The 140B came from the factory with a standard two prong AC cord...not good.
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If there's a ground pin on the AC try lifting it with an adapter otherwise...yea the AC Hz has ate through the caps.

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I have bought a lot of vintage equipment over the years, including quite a few amplifiers from the 40s and 50s.

 

Sometimes, you can solve the problems by reheating the solder joints. Solder scales over time, and simply re-liquefying the solder can remake connections that were turning into capacitors. Go through the circuit, re-making every connection (including the jacks...) I ONLY recommend this if you are knowledgeable about working inside of electrical equipment though. If not, do NOT do this.

 

When doing this, give a visual inspection to the parts. Cooked resistors are pretty obvious, but it is often possible to see other flaky parts, too.

 

And then there are the big caps in the power supply. They dry out over time, and need replaced.

 

No not, EVER lift the ground pin. EVER.

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