All a friend of mine just dropped off a radio that came off his 1936 Graham automobile. The radio is a Philco Transitone model 802. What's weird is that it looks nothing like the Philco 802 that's on Nostalgiaire site. This one has a chassis that's separated from the control head and the speaker. The 7 tube chassis is square. Anyone know where I can find a schematic for this model? I've only done a couple of car radios but this one has plenty of room and should be easy to restore.
Thanks in advance,
Keith
All, Apparently this one is different from Mopar Philco 802. Chuck Schwark found the manual for it and I'll have it shortly. Here's a picture of the radio controls in the dash.
Keith
OK guys, I need some advice. I've never worked on a car radio is this old. My first question has to do with this interference filter that I've got shown in the schematic boxed in red and in the attached photo. It appears to be a coil and 250pf capacitor that I believe is potted in Tar. I'm not sure if I need to mess with this one or not. Can I melt off the tar and then replace the cap? The next question involves the buffer capacitor. It's a 1250pf capacitor, can I replace it with a 1000pf ceramic cap? I've ordered a new solid state vibrator for this radio. My last question regards the polarity of the electrolytic caps. I've never worked on anything that was positive ground so I need to make sure I've got this right. Is the negative side of the electrolytics attached to the ground?
Thanks in advance,
Keith
Well, I've finally got this thing playing. I replaced all of the resistors and all the film and electrolytic caps. I went with a 1000pf buffer cap rather than the 1250 but I don't know if it makes a difference since I'm using a solid state vibrator. I do have a high pitch hum problem. The hum comes out of the speaker and you can hear it instantly when the radio is turned on. After about 30 seconds when the tubes warm up the broadcast stations become audible but the hum is still there, although not as loud. Any suggestions?
Thanks in advance,
Keith
I would go back and replace the 1000 mmf/pf with something closer to a 1250 pf, or larger, values are usually fairly critical, use a film cap don't use a ceramic disk cap. I have read mixed reviews regarding the ready made solid state vibrators, in some cases the manufacturer didn't bother heat sinking the switching transistors, or relied on the copper foil on the PC board for a heat sink, which can cause them to fail, I bought a kit from WJOE radio for an SS vibrator but have yet to use it but will add extra heat sinks when I do, but I am going to try to get it going with the original vibrator first.
As to the high pitched hum I can only guess, if one filter cap was not connected correctly, like it was connected to the chassis rather then B- it could cause that, or it could be related to the hash capacitor, I would also look at part #78 the .01 uf across the H.V secondary. Are you running the set off of a battery, a well filtered 6.3 volt DC power supply, or something like a battery charger? I would leave that interference filter alone, unless that 250 mmf cap is known to be paper and not mica, and at 6.3 volts it's unlikely to fail.
Regards
Arran
(This post was last modified: 12-24-2016, 02:01 AM by Arran.)
glad you got it running. Looks cool in the dash! Now you need to show us a pic of the whole car!
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