Model 52 voltage issue - Printable Version
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Model 52 voltage issue - Pear - 06-24-2017
New to forum ,I am, but not new to radio repairs.I got a model 52 for $25 since the cabinet is very nice. Easy redo, correct? No, I have hit the wall and am NOT finding why.The I F tube, type 35, has 300V on the cathode.Should be around 3 volts.On schematic it is connected on the volume control side of a 51K resistor.The other side of the resistor goes to B+. The volume pot is fine (5.2K) and the small resistor (34) is new and 220 ohms.
The I F tube is fine, no shorts on Hickok, all tubes are good. B+ is a little high, but that's not the problem.
The only thing I can think of is when I restuffed the bakelite cap. (34) I got the connections wrong way around and the 220 ohm part of 34 is not connected to the cathode lead. Does that make sense? Is there anything else that can raise the cathode to high voltage that that anyone can suggest? Grid, plate are close to proper Voltage.
Thanks,
Pear
pearsrepairs@hotmail.com
web:pearsrepairs.com
P.S, Ron R., I read all the Philco history sections, nicely done, very good forum also.
RE: Model 52 voltage issue - Radioroslyn - 06-24-2017
Hi Pear and Welcome,
Sounds like #1 ( 1/2 of the volume control) or #34 is open. Simple test is measure the resistance from the cathode to chassis gnd, should see with volume control full up abt 250 ohm. Set unplugged of course.
http://www.philcoradio.com/images/phorum/schem/51.jpg
GL
ps Didn't read your full post to answer your question Yes it's a very good possibility. Under normal conditions a shorted tube wouldn't deliver HV to the cathode w/o either showing a low plate voltage or smoking the cathode resistor. In your case the cathode circuit is open.
RE: Model 52 voltage issue - klondike98 - 06-24-2017
Welcome to the Phorum!
I've miswired a few bakelite blocks in my day too...
RE: Model 52 voltage issue - Pear - 06-25-2017
Yes it was the bakelite block, I put the resistor and cap in wrong order, so basically the cathode was floating at b+ levels and circuit to volume pot was not complete. Reversed items and she came to life. A little tweaking on the trimmers and she functions pretty well considering how basic she is.
I sort of came up with the answer as I asked the question.
The ONLY circuit diagram I found that showed ALL the values was right here on the phorum.
NICE!
Thanks,
Pear
RE: Model 52 voltage issue - Arran - 06-25-2017
That's because Philco used to use numbers on the schematic to identify parts, which would then have to be looked up on the parts list, rather then writing the part values on the schematic itself. Fortunately they changed this practice as time went on, other companies did not, Sparton for one, in such cases I make a photo copy and then write in the values on the copy so I don't have to keep going back and forth between the schematic and the parts list.
Regards
Arran