[KCMike]

I recapped "all caps except micas" and changed resistors as needed. I had to put on shelf for 3 months till I found a correct speaker which I did and ordered an ot8se universal output transformer. I got the transformer and hooked it up tp speaker.
I brought the radio up on variac and had no sound. So I touched grid cap of 75 tube and got some static with volume all way up. Then I noticed the 42 output tube glowing blue,very blue so I turned off.
Pulled the 42 and started checking voltages The 80 has 384 V. Plate to cathode. 6A7 P to K =346 , 75 P to K=201, 78-1st. IF=344 PtoK
78 2nd. IF=260 P to K. And the 42 P to K =456 with tube out.
Could mis- wiring output trans cause the high voltage on the 42?
I hooked the blue 7K OHM wire to the 42plate pin out. The 80 to field coil plus the B+ from the OT. and the 42 grid to the other field coil wire. On secondary black wire (0 ohm)to one voice coil wire and grn wire (3.2ohm) to other voice coil wire. I realize all the voltages are high. How should I procede to trouble shoot this problem? It took about 20 minutes to ck the tube volts and the power transformer just got warm to touch, not hot at all. I hope thats a good sign. Thanks. Mike

[morzh]

1. Have you checked your tubes?
2. Have you checked them for gas?
3. Pulling the output tube by itself will raise the voltage as the load drops.
4. usually mis-wiring output transformer does not raise voltage above what you give the stage from the rectifier. However if you swapped input and output, then your tube will receive higher voltage.

[KCMike]

Thanks morzh, I bought them new from vacuum tubes inc. and checked them on my 177a military tube tester a few months ago. They tested good for no shorts and emission. I will retest them. I thought about the higher voltage because the tube was out. The 42 calls for 300v P to K. and the 456 v. I got I guess is not too high with tube out? I took all the readings for each tube and can post them if that will help. I was double checking on the ot wiring just to be sure. Mike

[morzh]

Also check your variac output voltage, make sure that if it says 110V it is 110V and not 130V.

Last thing:

Blue glow in some tubes is perfectly normal. It may be glass itself when bombarded with electrons, some types of metal. So, measure your voltages in fully working mode and disregard the glow at least for a while.

[KCMike]

Will do and post what I find.I did ck variac voltage with fluke dmm. and set it for 120v after bringing radio up slowly first time. Mike

[morzh]

One thing is, try not to exceed 110-115V while you are fixing it. I found out some radios at about 115V and up will produce a loud hum they are not producing at below 115V. I spent 3 hours trying to rewire grounds in my 38-15 to get rid of the noise only to eventually realize it does not even show if I am under 115V.
One less variable. Once you fix it you may try unadulterated Mains voltage to see if it behaves well.

[KCMike]

Ok, I rechecked the voltages with all tubes in chassis. Heres what I have.( 6A7 P to K =332v,SG to K=66v, K to Gnd = 1.8v,G2 to K=272v, G1 to K =16.67)
(42 tube P to K =423v , SG to K = 14.16v ???)
(75, P to K =201v) (78 1st IF, P to K =329v) (78 2nd IF, P to K =103.9v ??) I did change the variac to 115v before this test.
I had radio on for about half an hour while testing and the 42 tube did not start glowing blue. All filiments lit and tested at 6.5v and the 80 at 5.3v. I did try the grid touch test of the 75 and now I don't get any static as I did previously. I still need to retest tubes and plan to this eve. But I wanted to get these volt readings posted they seem too high. Any other advice on things to check greatly appreciated. Mike Sorry the 80 tube is 369v to gnd.each side and 738v v P to P.

[morzh]

1. What kind of meter do you use? A todays DMM?
2. Do you have the original speaker and does the Field coil have the proper resistance?
3. What is our Rectifier cap's value (should be 8uF), I think it is #68.
4. Are your resistors #30 (21 and 263 Ohms) OK?


Oh! There's that mistake in the sch again.

How did you connect the Cap #67 that goes to the Resistor #54? It needs to connect to the B+ after the field coil. And the dot is missing.

[KCMike]

Its a fluke mod. 73III multi range tester. I did these test as per philco voltage chart with settings as described in the chart. I got all the info and and enlarged schematic from Chuck Schwark. I will get the rest of your questions answered as soon as I can. I have a # 67 on parts list that was a 8-8-10 cap. It had been bypassed sometime in the past so I took out the caps that they used to bypass #67 and used 10uF elect. caps 450v in there place. My parts list shows #50BC(263ohms-21ohms wire wound). I will recheck it and post result

[morzh]

I think #67 to resistor #54 is probably OK as otherwise there'd be no voltage on 75's plate. Still check it.
10uF is OK i/o 8uF.

FLuke will measure higher value as that in the sch as it is very high impedance and does not load the voltages unlike the old 10kOhm/V meters.

[KCMike]

I just checked #50 bc wire wound It reads 20.9ohms and 286 ohms, not 263 as it should be. Is 286 too high? That looks like it might be hard to find a replacement for. Sorry morzh had to edit this. The speaker is the correct 660 ohm field coil 10.5 inch dia. It is an H-29 where as the original was H-16. I conversed with Ron Ramirez a while back and he said as long as it has the 660 field coil it will work but finding correct output tranny could be challenge. Thats why I bought the universal otse with the 7000ohm option for the plate load of the 42 tube.

[KCMike]

I retested all tubes in the philco 144. Found the 42 is bad and replaced. I powered back up with variac to 110v with a dim bulb tester and amp. meter. The amperage draw is reading right at .5 amps. I can get some low pitched squeel/static when touching the 75 grid cap or the lugs on the volume control. With volume 3/4 to all way up. I have a 12 guage copper wire from ant. to water pipe.
I really will appreciate any advice on how to proceed to trouble shoot from this point. I can post pics of before and after recap if needed. Thanks Mike