Westinghouse N-202 - Printable Version
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Westinghouse N-202 - klondike98 - 03-29-2022
Took the initial look at this set. The schematic is a bit problematic. N-202 is not listed in Riders or other sources but after searching around apparently the M102/M111 model is similar and found in Riders.. It has an error which has been corrected by Leigh Bassett and which he has kindly provided.
As received:
[Image: https://www.dropbox.com/s/hiolz1i9gtai6er/WestinghouseN202_01.jpg?raw=1]
[Image: https://www.dropbox.com/s/ie32kd5bg21mzce/WestinghouseN202_02.jpg?raw=1]
[Image: https://www.dropbox.com/s/nf3z152sf391mt4/WestinghouseN202_03.jpg.jpg?raw=1]
The set looks relatively unscathed from previous repairs. It will need to be stripped pretty far down since much of the wire is the crumbling insulation of the mid 40's and the tuning cap grommets are all but gone as well. One of the bolts holding the tuning cap down is missing and that has caused it to twist a bit making the dial string bind so a restring will be in order when the tuning cap comes off.
As I looked it over, here's a component I had not seen before:
[Image: https://www.dropbox.com/s/lyx5ra47bcixcmf/WestinghouseN202_04.jpg?raw=1]
When I find it on the schematic it looks like its a pair of 60picofarad capacitors, C17A and B on the schematic. A close look and some testing shows the center mounting bracket is ground and there are a set of dielectrics and connection on each side of the bracket. Interesting.
More later...
RE: Westinghouse N-202 - captainclock1988 - 03-30-2022
It looks like this might of been an export model? If so that might be why this model wasn't covered in any of the American service data sources?
RE: Westinghouse N-202 - klondike98 - 03-30-2022
That's possible, thanks.
RE: Westinghouse N-202 - GarySP - 03-30-2022
Good luck, Bob. I'm sure there isn't anything in there that will slow you down too much. That is an interesting radio! Can't wait to see what the finished product will look like. Take care and BE HEALTHY! Gary
P.S. Are you replacing the wiring, or shrink-wrapping it?
RE: Westinghouse N-202 - klondike98 - 04-03-2022
I am replacing wire for the most part but using shrink tubing on a few places where it’s easier than unsoldering a bunch of components. Will not be stuffing paper caps or reproducing dog one resistors on this one. The dual 20uF electrolytic cap can will only fit one modern axial cap so the other will need to go under the chassis. Have replaced wires in the 1st IF transformer, a few pics later.
RE: Westinghouse N-202 - klondike98 - 05-06-2022
Finally able to get back to working on the chassis for this Westinghouse N-202. But I have a problem....
[Image: https://www.dropbox.com/s/5kwh5rdom76a0rv/WestinghouseN202_05.jpg?raw=1]
When I first powered it up I knew the 6SA7 tube tested bad on one of its test settings but tried it anyway. The set has sound with the normal static but was not picking up stations. I then put in a new good 6SA7 and was receiving stations on the AM band. It lasted about 30 seconds or so. I rechecked the 6SA7 tube and it was still testing OK. A few days later I fired up the set again and it was now picking up AM stations and sounded OK for about 5 minutes but then stopped receiving. I did an oscillator check with another radio and believe my oscillator circuit is not working. Cleaned the band switch. Checked voltages (see the schematic below with voltages in red in the "voltages at sockets" box in the schematic.) Rechecked caps and resistors around the oscilator circuit and ohm checked the oscilator transformer and things look ok but I can't figure what is giving me the low voltage on pin 4 of the 6SA7 and that may not be the problem either. I'm not sure what else to do at this point. Any suggestions are welcomed!
[Image: https://www.dropbox.com/s/db4xi4i6izd1tek/Westinghouse%20M102-111%20CORRECTED-with%20VOLTAGES%20in%20RED.jpg?raw=1]
RE: Westinghouse N-202 - Mondial - 05-06-2022
There is really not much to the oscillator circuit, but it definitely seems not to be working. Since you tried different 6SA7's its most likely not the problem. One suspect would be the 50 pF coupling cap C9. If its open intermittently, the osc will quit. You can try jumping another cap 50 to 100 pF across it and see if it cures the problem
If the osc coil has an intermittent winding is would also be a cause along with an intermittent 25K screen grid resistor R2. The voltage on pin 4 is low which could be caused by R2, but the low voltage could also be a symptom of the tube not oscillating. Try jumping a 22K resistor across R2 and see if it makes a difference.
Just a few things to try ... Good luck!
RE: Westinghouse N-202 - captainclock1988 - 05-07-2022
Now this thread has me curious because I had an old Westinghouse AM/FM Radio from 1948 or so a Model H-1821 (H-182 in the Riders) that used all miniature tubes, and in that radio both the AM and FM bands were "dead" (it wouldn't pick up any stations no matter what kind of antenna you used) and I fully recapped the radio, replaced all "out of tolerance" resistors, and replaced any tubes that tested questionable on my tube tester (mainly the 12AT7 and the 19T8 which both tubes are notorious for failing in this particular circuit setup) and I still had no stations being picked up on the radio on both the AM and FM band so I basically just gave up on that radio, but this thread might give me some ideas as to what I should look out for in the future if I run into another Westinghouse radio.
RE: Westinghouse N-202 - RodB - 05-07-2022
Hi Bob, try cleaning the tube socket and pins. If you've already done it, do it again. Be gentle but thorough, oscillators are temperamental.
RE: Westinghouse N-202 - klondike98 - 05-07-2022
Thanks for the suggestions! I did clean the tube pins and socket but will give it another go. Will give these a try.
RE: Westinghouse N-202 - RodB - 05-07-2022
Bob, check the voltage on pin 4 right away, then when it stops working. The voltage on pin 3 is good and there's R2, C10 and the oscillator coil in the circuit. I would take a close look at R2 first. But there's not that much current there and I assume you replaced C10 already.
RE: Westinghouse N-202 - klondike98 - 05-07-2022
Thanks Rod. I haven’t been able to catch it working and also measure voltages but that is something I hope to be able to do.
RE: Westinghouse N-202 - klondike98 - 05-14-2022
I clipped in a 100pF cap across C9 but it had no effect and I added a 25K resistor across R2 also to no effect although that did raise the voltage on 6SA7 pin#4 to about 65 volts. I did some additional checking to see if the oscillator transformer was shorting and did not seem to find anything wrong. However I did find that the resistance to ground at the point where you see the RED dot in the schematic below was 485 ohms. I could not see any reason that it should be that low unless one of the capacitors was leaking badly. C25 (a 5pF) cap seems to be the culprit and when isolated I see 485 ohms across it. Unfortunately I don't have a 5 pF cap to replace it so will have to order one to confirm whether this is the problem or not with the oscillator. We'll have to wait and see....
[Image: https://www.dropbox.com/s/z3k4f96ea4pmxn9/Westinghouse%20M102-111%20CORRECTED-with%20RED%20DOT.jpg?raw=1]
RE: Westinghouse N-202 - RodB - 05-14-2022
Bob, try winding two insulated wires together about 10 turns to make a gimmick capacitor.
RE: Westinghouse N-202 - Chas - 05-15-2022
I have noted from the clear images that this radio relies a LOT on riveted connections to the chassis. Mechanical connections to dissimilar metals can develop a problem at the "joints"...
I suggest soldering all those connections to the chassis or drill out the rivet and replace with serrated washers and hardware.
Since troubleshooting has centered around the oscillator, the mount for the tube socket and antenna/oscillator coil may rely on these riveted joints, solder them securely. A DC ohmmeter will not disclose the issue...
GL
Chas