Looking for help with first chassis restore.

[Tom Bavis]

Pull the tubes and recheck - if the dim-bulb (40W or greater) glows brightly, the transformer is shorted or AC is connected incorrectly. You could have crossed supply and return wires on the line-to-line cap block. There COULD be short in the block, but new caps are seldom bad... by the way, 'Y' capacitors - safety-rated for lin-connection - are the ones to use in that location. Regardless of the original value, I use .01 or .015 uF capacitors here to limit the amount of "leakage current" to well under 1 mA.

Also, cap item 36 shouldn't be increased - it will cause loss of high frequencies (there's already a 'Low" position on the tone switch - do you want "Low" and "Lower"?). Use .005, not .05.

[sean]

If this set is like other 1939 Philcos I have worked on, the leads to the power transformer are probably rubber insulated. If so, you might want to check the condition of the insulation to see if any of the leads have shorted. It is recommended that the rubber insulation either be sleeved with some heat-shrink tubing or the wires be completely replaced.

[BostonDave]

Originally Posted by sean

If this set is like other 1939 Philcos I have worked on, the leads to the power transformer are probably rubber insulated. If so, you might want to check the condition of the insulation to see if any of the leads have shorted. It is recommended that the rubber insulation either be sleeved with some heat-shrink tubing or the wires be completely replaced.

I had expected to find a lot of rubber insulated wire in there (my 1936 Rogers-Majestic is full of it), but the 39-25 had almost none. All cloth-covered and it all appears to be in very good condition. All of the leads going into the transformer are cloth insulated and they all look good. If there is no short the bakelite block I'll open the transformer tonight and see what's happening in there.

[BostonDave]

Originally Posted by Tom Bavis

Pull the tubes and recheck - if the dim-bulb (40W or greater) glows brightly, the transformer is shorted or AC is connected incorrectly. You could have crossed supply and return wires on the line-to-line cap block. There COULD be short in the block, but new caps are seldom bad... by the way, 'Y' capacitors - safety-rated for lin-connection - are the ones to use in that location. Regardless of the original value, I use .01 or .015 uF capacitors here to limit the amount of "leakage current" to well under 1 mA.

Also, cap item 36 shouldn't be increased - it will cause loss of high frequencies (there's already a 'Low" position on the tone switch - do you want "Low" and "Lower"?). Use .005, not .05.

I did use .01uF 'Y' caps in the block. I will surely double check again tonight to make sure I didn't wire them incorrectly in there before opening up the transformer to look for trouble.

The .006 cap for part 36 has been on order. The other cap was already snipped before I realized I didn't have a proper replacement so the .05 went in for now. I'll be sure to size that cap properly when the one on order arrives.