05-11-2010, 10:53 PM
Hi Vinzer,
I second the motion to check all the rivets used as tie points to ground.
In '06 I also recapped a Philco 84, and still had a hum. Not so much of distortion though. Turned out to be the ground tie point on the 77 tube. As Ron says, this set should perform pretty well for what it is.
When you think of it, there are two surfaces where the failure can be. Lug to rivet, rivet to chassis on the other side.
Bad rivet to ground connection.
[Image: http://antiqueradios.com/albums/Philco/P...dRivet.jpg]
IIRC, this connection was showing half an Ohm, which in the scheme of things is not a good connection. A simple jumper wire to ground as a test showed this was the bad rivet.
As a precaution, I soldered a small wire to ground on all the other tie points. You may have more than one bad connection causing distortion.
You could test each rivet to ground, just for fun, and see if you have one that shows even the slightest amount of resistance. I like to try and pinpoint where a problem is.
You can then do them all as a preventative measure
Here is my original thread on the 'alternative' site.
http://antiqueradios.com/forums/viewtopi...ight=rivet
A couple of years later, I recapped a Truetone that displayed the same hum. Checking the ground and tie points again solved the problem. I think that this may be a common issue, and one should check these points on every set we restore.
Hope this solves the problem,
Gary.
I second the motion to check all the rivets used as tie points to ground.
In '06 I also recapped a Philco 84, and still had a hum. Not so much of distortion though. Turned out to be the ground tie point on the 77 tube. As Ron says, this set should perform pretty well for what it is.
When you think of it, there are two surfaces where the failure can be. Lug to rivet, rivet to chassis on the other side.
Bad rivet to ground connection.
[Image: http://antiqueradios.com/albums/Philco/P...dRivet.jpg]
IIRC, this connection was showing half an Ohm, which in the scheme of things is not a good connection. A simple jumper wire to ground as a test showed this was the bad rivet.
As a precaution, I soldered a small wire to ground on all the other tie points. You may have more than one bad connection causing distortion.
You could test each rivet to ground, just for fun, and see if you have one that shows even the slightest amount of resistance. I like to try and pinpoint where a problem is.
You can then do them all as a preventative measure
Here is my original thread on the 'alternative' site.
http://antiqueradios.com/forums/viewtopi...ight=rivet
A couple of years later, I recapped a Truetone that displayed the same hum. Checking the ground and tie points again solved the problem. I think that this may be a common issue, and one should check these points on every set we restore.
Hope this solves the problem,
Gary.
