[Elijah]

I have a Model 20 Deluxe I bought around 1988 at an Antique mall and began replacing most all of the caps and resistors and a fair amount of the wiring. I didn't know how to replace the filter caps in the can back then so I added a terminal block under the chassis and added the four caps there and disconnected the wiring from the can to the circuit to those mounted on the terminal block.

Lately after learning how easy it was to remove this can and add either electrolytics or standard caps, which I opted for the latter, I began chasing out the wiring from those caps to the transformer and filter choke and discovered the factory wiring had not agreed with the schematic. The schematic shows terminal point 11 on the transformer going only to one side of the filament on the rectifier tube. This radio is wired with point 10 going to one side of the filament. In other words, the technicians reversed points 10 and 11 on the transformer to wire to the filament. So, point 11 on the radio actually goes to one side of the filament of the 80 tube and then to the filter choke and the two filter caps. Does that really make a difference or should I rewire per the schematic?

[Radioroslyn]

I think your question is does it matter which side of the filament on the 80 tube you use to connect for the dc hv connection. The answer is no you can connect to either side pin 1 or 4 it makes no difference.
Terry

[Elijah]

In essence, the schematic shows pin 11 on the transformer connected to the filament only(one side). My wiring shows pin 10 instead.

[morzh]

In most direct heating tubes the filaments are symmetrical, so it does not matter which pin of the two goes where.
It may matter in those with a midpoint, but this is not the case.

[Elijah]

The Model 20 is a good looking radio and I had sit it aside for some years and wanted to finish the chassis restoration. With the advent of putting the filter caps back where they should be in the can and a possible alignment, I think this will finish it up.

[Image: http://i180.photobucket.com/albums/x220/...EF4610.jpg]

[TA Forbes]

[morzh]

Have you restored the cabinet yourself or have you bought it this way?
One nice looking cabinet for a 20.

[Elijah]

It sure didn't come that way. I did part and another guy helped. Turned out pretty fair.

[codefox1]

Matters not 99% of the time. Stick with the plan for the other 1%.

[Elijah]

I finally finished recapping the filter caps and had to scrape and eventually burn out some of the tar to get the 630v caps in the can. I probably didn't need to use 630v but since the originals were rated at 1200, which I thought was an overkill, I didn't think they'd pose much of a problem other than fit. The 1.5 uf was of course the largest but, I got all of them in, did some rewiring due to the old wires being brittle and green looking.

I replaced the two 71A output tubes and the detector tube and hooked up a 20 ga wire for the antenna but no ground. It pulled in quite a few station just sitting on the work bench and the only problem is a slight hum between where no stations are and a fairly loud crack when you turn it off. Other than that, I'm pleased with it. All filter and bypass capacitors were replaced as were all resistors. I had done most of that before. It's playing better than ever other than the above.

[Radioroslyn]

The crack when you turn it off is normal. It's the det and audio stages hearing the arcing in the power switch. You could try a little deoxit but I don't think it will go away completely. Common with most TRF sets.
Terry

[Elijah]

That being the case I guess I can live with it. The on/off switch looks to be a sandwich of wood wafers, for lack of a better word, and unlike the volume control I couldn't see how to spray it with contact cleaner.