Philco 37-660 Hum - Printable Version
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+--- Thread: Philco 37-660 Hum (/showthread.php?tid=8782)
Philco 37-660 Hum - mgambuzza - 02-15-2014
Finally got into working on this radio after a few years of ownership and letting it sit. Replaced Electrolytics - what a pain on the ones in the RF section!! I am now picking up stations very well but have a residual issue - low grade hum. This is not the obnoxious that existed before the original electro's were replaced but it is enough to be distracting. I have been going through replacing the other paper caps - and have not gotten into bakelites as of yet - could one of these be the culprits or is there something else I should be looking at?? Before I moved onto other projects I thought I'd look to the experts and see if I'm missing something that can bring this to a solid working state.
RE: Philco 37-660 Hum - gregb - 02-15-2014
If you haven't recapped the rest of the radio there maybe a leaky cap or two or three drawing excessive current. It is possible to have a bad tube with heater/cathode leakage. Check the 6F6 tubes, if one is really weak that could cause some hum. Just some thoughts.
Gregb
RE: Philco 37-660 Hum - morzh - 02-15-2014
Does the hum change when tuned in?
RE: Philco 37-660 Hum - mgambuzza - 02-15-2014
The hum still exists when tuned in. I did notice when not on a station and varied the volume the hum would minimize then return. I'll look at the options described above and if any other suggestions feel free to chime in.
Tx. Mike
RE: Philco 37-660 Hum - morzh - 02-15-2014
What you have not answered is whether you did full recap.
RE: Philco 37-660 Hum - mgambuzza - 02-17-2014
Gm
Did not do a full recap but did find issue- neg of 8uF electro caps was on chassis- once corrected now functions as should. I also as a precaution checked all tubes and all tested in tolerance.
Thank all for assist and direction!
RE: Philco 37-660 Hum - morzh - 02-17-2014
Are you sure the neg should not be on the chassis?
Post the link to the sch, it will make it easier.
Again.
Do the recap.
Do the recap.
Do the recap.