02-21-2006, 11:09 AM
I have a Philco 37-690 20 tube monster. I have the chassis out and I am trying to use my limited knowledge to get this thing to work.
-First time I turned it on and all the tubes lit up, but no joy on any sound, not even static out of speaker.
-Tested all tubes, found nine bad ones.
-Replaced all bad tubes except one 5X4G (tested at 50%, the other tested at 65%).
-Turned set on and I picked up a station. I think on BC AM. A lot of scratchy static when turning tuning knob. Also, hum coming out of main speaker that stayed at same volume. Seemed to be typical of electrolytic hum. Little to any volume control.
-Set to work to replace electrolytic caps. All e caps are on power sub chasis. Initial inspection of sub chassis showed that some rewiring had taken place wrt to e-caps. Rewiring looked professionally done using same type of cloth covered wire as rest of sub chassis. Because of this, I have replaced the caps in question exactly as I have found them. The original e-caps were all in cans. Some have already been replaced with cans of an aftermarket brand. Again, wired with same type of cloth covered wire as original. Replacement cans have a higher mfd rating than schematic calls for.
- So far, I have replaced the e-caps with schematic rated Mfd. or with rating I found on replacement caps. I still have a hum out of the main speaker. Also I have no sound at all from the two "tweeter" speakers.
I still have two e-caps to go. One is part number 168 and the other is 165. Problem with 165 is that with two red wires coming out of the bottom of the can and one black, I dont know how to wire in a new axal cap. For the part number 168, there is a single junction coming out of the can (this appears to be one of two original cans left). Both wires connected appear to be the same color and one goes to another e-cap (166). How do I wire this one?
-I have not replaced any regular caps on the audio chassis
Additional Questions
-Would the lower producing 5X4G be a problem? What percent of tube value is ok?
-Should I continue with the way I found the subchassis wired or should I try to wire it back to original schematic? I know they did some mods to the Philco 690, but the bulletins don't seem to indicate this type of mod.
-Why won't the two additional speakers work at all? I get nada out of them. Both are linked to the sub chassis, so you would think I would get something if the main speaker was operational.
-Does radio shack sell TV Tuner/cleaner. I would imagine this is a reason for static/scratchiness when moving the tuning knob? Would cleaner work on the variable (tuning) condenser?
-Can somebody tell me what a magnetic tuning knob does? Unfortunately, with out an owners manual, I have no idea how to properly operate this radio, whch bands are for what, etc.
Any and all help would be appreciated. PS, I picked up this radio for 100 dollars at a garage sale. I have already spent more money on tubes and caps than I payed for it. I understand the sound that comes out of this thing should make it worth it. True? Anybody else out there have one of these?
Thanks, MG
-First time I turned it on and all the tubes lit up, but no joy on any sound, not even static out of speaker.
-Tested all tubes, found nine bad ones.
-Replaced all bad tubes except one 5X4G (tested at 50%, the other tested at 65%).
-Turned set on and I picked up a station. I think on BC AM. A lot of scratchy static when turning tuning knob. Also, hum coming out of main speaker that stayed at same volume. Seemed to be typical of electrolytic hum. Little to any volume control.
-Set to work to replace electrolytic caps. All e caps are on power sub chasis. Initial inspection of sub chassis showed that some rewiring had taken place wrt to e-caps. Rewiring looked professionally done using same type of cloth covered wire as rest of sub chassis. Because of this, I have replaced the caps in question exactly as I have found them. The original e-caps were all in cans. Some have already been replaced with cans of an aftermarket brand. Again, wired with same type of cloth covered wire as original. Replacement cans have a higher mfd rating than schematic calls for.
- So far, I have replaced the e-caps with schematic rated Mfd. or with rating I found on replacement caps. I still have a hum out of the main speaker. Also I have no sound at all from the two "tweeter" speakers.
I still have two e-caps to go. One is part number 168 and the other is 165. Problem with 165 is that with two red wires coming out of the bottom of the can and one black, I dont know how to wire in a new axal cap. For the part number 168, there is a single junction coming out of the can (this appears to be one of two original cans left). Both wires connected appear to be the same color and one goes to another e-cap (166). How do I wire this one?
-I have not replaced any regular caps on the audio chassis
Additional Questions
-Would the lower producing 5X4G be a problem? What percent of tube value is ok?
-Should I continue with the way I found the subchassis wired or should I try to wire it back to original schematic? I know they did some mods to the Philco 690, but the bulletins don't seem to indicate this type of mod.
-Why won't the two additional speakers work at all? I get nada out of them. Both are linked to the sub chassis, so you would think I would get something if the main speaker was operational.
-Does radio shack sell TV Tuner/cleaner. I would imagine this is a reason for static/scratchiness when moving the tuning knob? Would cleaner work on the variable (tuning) condenser?
-Can somebody tell me what a magnetic tuning knob does? Unfortunately, with out an owners manual, I have no idea how to properly operate this radio, whch bands are for what, etc.
Any and all help would be appreciated. PS, I picked up this radio for 100 dollars at a garage sale. I have already spent more money on tubes and caps than I payed for it. I understand the sound that comes out of this thing should make it worth it. True? Anybody else out there have one of these?
Thanks, MG
