[Pithicus999]

Besides this 2 Watt resistor, all of the ones I'm using are 1/2 Watt resistors. I can't find anything on schematics about wattage, is it 'OK' to use 1/2 watt resistors for all the rest??

[jerryhawthorne]

Pith, if you look on your parts list for the Philco P/N for the resistor and refer to the following link to Chucks site you can determine the wattage of the resistor. Neat huh? You will get the hang of pretty quick, the bigger in physical size the higher the wattage. Resistance value has little to do with it.
Jerry

http://www.philcorepairbench.com/carbonres.htm

[Pithicus999]

Cool, I'll check it out thanks. I'm on nostalgia air currently trying to be sure I have the voltage measurements for tubes correct, but the tube link is not working. Schematics show 'H' & 'H' pretty sure that means 'F' and 'F' on the 'BIG' pins of the #78 tube...is there another site I can double check for tube pin identification etc. thanks.

[BrendaAnnD]

http://www.nj7p.org/Tube.php

[BrendaAnnD]

Also try: http://tubedata.tigahost.com/tubedata/index.html

[Pithicus999]

I am getting close.

While checking voltages I picked up a strong radio station (but only when I touched the ‘K’ and ‘DP’ pins of the # 75 tube with the volt-meter leads). I think I need to replace the I.F. #78 tube AND/OR the #80 tube?? Here are my results while checking the voltages, all other tubes have outrageously high voltages and the I.F. #78 tube and #80 tube are really low.

MY RESULTS ARE INSIDE THE [ ] BRACKETS.

Circuit R.F. Det. Osc. I.F. 2nd Det & 1st A.F.
Tube Type 78 RESULTS 6A7 RESULTS 78 RESULTS 75 RESULTS

Filament Volts: F to F 6.3 [5.9] | 6.3 [5.9] | 6.3 [5.9] | 6.3 [5.9]
Plate Volts: P to K 210 [600] | 210 [601] | 210 [2.9] | 120 [426]
Screen Grid Volts: SG to K 80 [158] | 80 [163] | 80 [164] | N/A [N/A]
Control Grid Volts: CG to K 0.3 [0] | 0.15 [1.1] | 5.3 [0] | 0.3 [1.2]
Cathode Volts: K to F 2.8 [9.3] | 2.8 [5.9] | 5.3 [12] | 0 [2.8]
G1 to K N/A [N/A] | 35 [2.4] | N/A [N/A] | N/A [N/A]
G2 to K N/A [N/A] | 130 [274] | N/A [N/A] | N/A [N/A]



Circuit Driver 2nd A.F. Output (Class "A") Rectifier
Tube Type 42 RESULTS 42 RESULTS 42 RESULTS 80 RESULTS

Filament Volts: F to F 6.3 [5.9] | 6.3 [6] | 6.3 [6] | 5.0 [ 4.7]
Plate Volts: P to K 205 [566] | 280 [642] | 280 [596] | 350 [58]
Screen Grid Volts: SG to K 200 [567] | 300 [642] | 300 [595] | N/A [N/A]
Control Grid Volts: CG to K 0.35 [31] | 28 [60] | 28 [60] | N/A [N/A]
Cathode Volts: K to F 0 [2.8] | 0 [2.8] | 0 [2.8] | N/A [N/A]
G1 to K N/A [N/A] | N/A [N/A] | N/A [N/A] | N/A [N/A]
G2 to K N/A [N/A] | N/A [N/A] | N/A [N/A] | N/A [N/A]


Also, I remember someone asking me to touch the ‘Center-tap’ with a screwdriver to hear a ‘HUM’? What is the ‘Center-tap’? Is that the back of the ‘ON-DIAL’ under the chassis?

Thanks.

[jerryhawthorne]

Pith, something is wrong with your measuring. The only measurements that were somewhat close are the filaments (A/C). All DC measurements (the balance of them) are sky high! Of interest are the cathode to ground measurements on the 42s for example. These set at chassis ground and yet your getting 2.8V on them. Not possible. As a question, are you measuring these tube voltages with the tubes in? Obviously the 80 rectifier was in to provide DC voltage. Note in your voltage chart that the chart is based on measurements from the cathode as the minus point for the meter, not chassis ground.
Spot try a few measurements again and see how they compare to your original posting above. Your obtaining some high voltage readings that the power supply is incapable of making under load.
Jerry

[Pithicus999]

I thought something was screwy...

Ok, so are you saying I need to be using the 'DC' section of the multimeter? I was using A/C....

[BrendaAnnD]

For the filaments and the power transformer connections to the 80 tube, you want to use the AC setting. For all other voltages, you need to use the DC setting.

[jerryhawthorne]

Bingo!!!!!!!!!!!!!!!!!!!
Jerry

[Pithicus999]

Ok, I've re-measured with DC for everything except the 80 tube and F-F contacts.

MY RESULTS ARE INSIDE THE [ ] BRACKETS.

Circuit I.F. Det. Osc. R.F. 2nd Det & 1st A.F.
Tube Type 78 RESULTS 6A7 RESULTS 78 RESULTS 75 RESULTS

Filament Volts: F to F 6.3 [5.9] | 6.3 [5.9] | 6.3 [5.9] | 6.3 [5.9]
Plate Volts: P to K 210 [272] | 210 [284] | 210 [1.8] | 120 [194]
Screen Grid Volts: SG to K 80 [70.8] | 80 [72.7] | 80 [72] | N/A [N/A]
Control Grid Volts: CG to K 0.3 [0] | 0.15 [8.4] | 5.3 [0] | 0.3 [.7]
Cathode Volts: K to F 2.8 [5.3] | 2.8 [2.2] | 5.3 [2.2] | 0 [0]
G1 to K N/A [N/A] | 35 [9.3] | N/A [N/A] | N/A [N/A]
G2 to K N/A [N/A] | 130 [160] | N/A [N/A] | N/A [N/A]



Circuit Driver 2nd A.F. Output (Class "A") Rectifier
Tube Type 42 RESULTS 42 RESULTS 42 RESULTS 80 RESULTS

Filament Volts: F to F 6.3 [5.9] | 6.3 [6] | 6.3 [6] | 5.0 [ 4.7]
Plate Volts: P to K 205 [257] | 280 [269] | 280 [291] | 350 [364]
Screen Grid Volts: SG to K 200 [257] | 300 [290] | 300 [269] | N/A [N/A]
Control Grid Volts: CG to K 0.35 [15] | 28 [27.4] | 28 [27.4] | N/A [N/A]
Cathode Volts: K to F 0 [0] | 0 [0] | 0 [0] | N/A [N/A]
G1 to K N/A [N/A] | N/A [N/A] | N/A [N/A] | N/A [N/A]
G2 to K N/A [N/A] | N/A [N/A] | N/A [N/A] | N/A [N/A]

The #78 tube looks like It giving me trouble. I think it was labeled incorrectly in the last post. I believe it's the R.F. #78 tube that is having trouble. Although, I have an extra one. So, I replaced the R.F. #78 tube and took new measurements...got the same results. Anyone have any ideas what is wrong? Maybe both 78's are screwy?
thanks.

[BrendaAnnD]

It looks like you have an open RF coupling coil (9) or open shadow meter (36). These are the only two points that could cause no plate voltage to the RF amp, but not to other tubes.

[jerryhawthorne]

Make certain the 78 with no plate voltage is the RF amp and not the IF amp. If the IF amp, possible problem with the primary of the 2nd IF transformer primary #27.
Jerry

[Pithicus999]

Thanks BrendaAnnD!

Jerry - It's definitely the RF #78 tube (right near the TWO #42 tubes on the right hand side when looking from the front of radio.)

BrendaAnnD, I think you may be looking at the 124 model? Mine is model 121. On the 121, #(9) and (36) are #(10) and #(63) so I can check out those, but not sure how or what to check for? A lose wire? Double check all connections maybe??

Um, when you say 'Open' I'm guessing you mean the shadow meter wire is not connected? The shadow meter does have a burnt out light bulb that I wasn't going to worry about just yet (mostly because I can't find the replacement bulb nor do I know which size it is)

I did see a very good youtube video where a guy removed the shadow meter, and used a permanent magnet to ‘Re-magnetize’ the tiny electromagnet inside..do you think I need to do that too?

[BrendaAnnD]

By open I mean that no electricity passes through it. This could be a wire broken off of the shadow meter, or it could be that the shadow meter's coil has opened up, or the plate resistor has opened up. Wish I had a copy of that 121 schematic, if there are minor differences that could affect my diagnosis, it would be good to know.