05-18-2016, 06:53 AM
Greetings! First post here.
Im a newb to restoration. I recapped and refinished my great grandmothers Philco 42-321 without much issue and enjoyed the process immensely so I picked up a 37-61 to try.
The 37 was/is much more of a challenge. The chassis was in far worse shape in terms of rust and brittle wire insulation.
So...Yes, I broke the newbie cardinal rule and replaced all the caps right from the get go. In my defense, some of the caps looked pretty bad already and the wiring to the speaker and transformer (and in several other spots) were so bad that it seemed foolish to desolder and replace everything I had to replace only to dig through it all a second time to recap one or two at a time.
I took what I thought to be copious notes/photos and markings and took my time.
Anyway. I dim bulb tested it (adding one tube at a time) and it powers up safely. The tubes light up, the pilot light comes on, etc.
Problem is there is absolutely no sound from my speaker. No hiss, no hum, no static...dead silent.
I am not an expert in electronics and am just starting to get a working understanding of schematics but I've done my best to check my work against the schematic and it looks as good as I can make it out. After doing a little research about troubleshooting I tried a couple of things. I tried touching the grid cap of the audio tube...nothing. I pulled the power tube while it was on...no sound. I can cross the speaker contacts with a 9v battery and get a very faint scratching sound but when powered up the voice coil rod has only the slightest hint of a magnetic pull on my nut driver. All the wires on the transformer and coil appear to be connected.
Am I correct in assuming that the voice coil is most likely shot and not start digging too deep into anything else till I get a new speaker to try? One of the old dog-bone resistors (9000 ohm 2 watt) attached to one of the filter caps is testing way over spec. 24k ohm on a resistor specd for 9k. Any possibility that could be part of the problem?
Of course it looks like it's gonna be a @#$%^ finding the same Philco #36-1009 speaker and I don't have any other electrodynamic speakers laying around to test on so now I'm in a holding pattern.
Im a newb to restoration. I recapped and refinished my great grandmothers Philco 42-321 without much issue and enjoyed the process immensely so I picked up a 37-61 to try.
The 37 was/is much more of a challenge. The chassis was in far worse shape in terms of rust and brittle wire insulation.
So...Yes, I broke the newbie cardinal rule and replaced all the caps right from the get go. In my defense, some of the caps looked pretty bad already and the wiring to the speaker and transformer (and in several other spots) were so bad that it seemed foolish to desolder and replace everything I had to replace only to dig through it all a second time to recap one or two at a time.
I took what I thought to be copious notes/photos and markings and took my time.
Anyway. I dim bulb tested it (adding one tube at a time) and it powers up safely. The tubes light up, the pilot light comes on, etc.
Problem is there is absolutely no sound from my speaker. No hiss, no hum, no static...dead silent.
I am not an expert in electronics and am just starting to get a working understanding of schematics but I've done my best to check my work against the schematic and it looks as good as I can make it out. After doing a little research about troubleshooting I tried a couple of things. I tried touching the grid cap of the audio tube...nothing. I pulled the power tube while it was on...no sound. I can cross the speaker contacts with a 9v battery and get a very faint scratching sound but when powered up the voice coil rod has only the slightest hint of a magnetic pull on my nut driver. All the wires on the transformer and coil appear to be connected.
Am I correct in assuming that the voice coil is most likely shot and not start digging too deep into anything else till I get a new speaker to try? One of the old dog-bone resistors (9000 ohm 2 watt) attached to one of the filter caps is testing way over spec. 24k ohm on a resistor specd for 9k. Any possibility that could be part of the problem?
Of course it looks like it's gonna be a @#$%^ finding the same Philco #36-1009 speaker and I don't have any other electrodynamic speakers laying around to test on so now I'm in a holding pattern.
