The PHILCO Phorum
40-180 & 40-190 restore - Printable Version

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40-180 & 40-190 restore - madsowry - 03-27-2019

Hi All     I'm restoring a 180 and a 190 at the same time cause they use basically the same schematic and their chassis are basically the same too.  The only difference is the 190 uses a 7A6 AVC tube and the 180 doesn't.
Now from what I have read these 40 radios don't perform like the 41s because they don't have feedback.  I saw this in a thread from 2014 by bobk9eui about a modification to put feedback into these 40 radios.  My question is has anyone else tried this mod and were the results as good as he states his was.

Here's the thread: https://philcoradio.com/phorum/showthread.php?tid=9151&highlight=40-190

 I understand all of the schematic except at the junction below the 220k res. and to the right of the .02 cap,  I don't understand what the symbols at that junction mean.  They just seem to stop.
   
I'm sure there is going to be more questions as I try to restore these 2 radios but this is my starting one.  Any help will be much appreciated.  Thanks

Dick

RE: 40-180 & 40-190 restore - Radioroslyn - 03-27-2019

> I don't understand what the symbols at that junction mean.

The thingy that looks like an upsidedown T is the plate of the 7C6. The thingy that looks like resistor w/one side connected is the control grid of the 7C6.

RE: 40-180 & 40-190 restore - madsowry - 03-27-2019

Thanks Terry   How stupid of me to not see that as a tube.  Oh well live and learn.
So what are your thoughts on the mod?  Have you installed it or do you know of anyone who has and were they happy with it?

RE: 40-180 & 40-190 restore - Radioroslyn - 03-27-2019

It's a circleless tube.
No I haven't but doesn't seem too difficult and no odd parts to obtain. The phasing of the output transformer might be critical, if not phased properly the amp may just oscillate. It's just a matter of reversing the wires on the secondary no big deal.

RE: 40-180 & 40-190 restore - madsowry - 03-28-2019

OK I think IF I get these radios working again I might try this mod on at least one of them.
 Another question:  While checking the components of the 180 I found the output trans. was open, which was discussed on a different thread.  Now I found the speaker field coil open too.  What kind of event would cause both trans. to fault at the same time?   The rest of the radio components all seem to be in working order.  So I'm just curious -- is there something to look for that would cause this event?

Thanks  

Dick

RE: 40-180 & 40-190 restore - Radioroslyn - 03-28-2019

Don't think they are related except for maybe humidity causing the copper wire to rot. Open opt on the '40 and '41 models is not too uncommon.