A snapping noise I cant figure out! - Printable Version
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A snapping noise I cant figure out! - Guest - 06-08-2006
Hi everyone I am new to this forum along with new to repairing antique radios. I am hooked and also stuck. I Hope someone can help me. have an eight tubed Philco 40-190. I replaced some dried out plastic wires, the elect. caps, and half of the regular caps. It is working but I have a low snapping noise coming out with the audio. It speeds up when I turn up the volume then disapears. What is causing this and what should I replace first? Could it be a tube, resistor, or even a choke? Has anyone had an experience like this. Thank you for any help.
- Terry Judkins - 06-08-2006
Replace ALL of the paper capacitors would be my take on the matter. Then troubleshoot. But you can pull the first audio tube and see if the popping continues. If not, the trouble is in the RF/IF stages or detector. If it continues it is in the audio circuits. Bad leaky caps will/can cause the snapping symptom. Tubes are usually good in thease old radios although it is possible to have a bad one cause your symptom.
- Chuck Schwark - 06-08-2006
Could be B+ arcing in the bandswitch due to dirt/crud or a carbon track between contacts. ?
- rghines1 - 06-10-2006
Since the noise speeds up with increase in volume, this seems to be motorboating. Be sure all the tube shields are in place and making good contact with chassis. Consider replacing the remainder of the paper caps. Since you replaced some wire with bad insulation, getting the wires back where it was originally may be necessary to avoid stray coupling.
Richard
Problem solved thank you - Guest - 06-24-2006
Thank you everyone for your help. I changed out all the caps. I did not mess with any of the resistors. It just goes to show that a cap can be bad even if it looks good. The final three I ended up changing out showed no signs of leaking or dry rot. They were hard to get to and looked fine that is why I left them. The snapping noise is no longer. I Changed out the caps and tested the radio. It works great. I will try to attach a pic of it. Thanks again.