[jcassity]

0 ohms at both points you asked to measure.

I lifted the wire from R100 to C101 neg terminal.

measured from T100 Green to the far end of R100 and got 272 ohms.

sounds like a problem in my C101 filter group?

as in take it apart again?

[jcassity]

why do i feel like what i just said is impossible... LOL

[Mondial]

Yes, you definitely have a short to ground somewhere. Don't measure resistance to R100, measure directly to ground.

If you are reading 0 ohms from the green center tap wire to the chassis, then there probably is a short in the transformer. It looks like you resleeved the transformer leads, so I would check there first. Maybe the green wire got pinched or the wire is touching the core or case inside.

In any case, disconnect the green wire from the terminal strip and measure resistance to chassis ground. Likewise, measure C101 negative to chassis. See which is shorted to the chassis.

I am very surprised that you said the radio played fine, because with the green wire shorted to ground there is no negative bias on the output tubes. In this condition, the audio would be very distorted, which you did not mention.

This also explains why the 300 ohm resistor is getting very hot. With no bias the output tubes will draw excessive current ( unless they are so weak they can't).

[jcassity]

found the problem....  see below picture.

it was all wired correct and to my frustration i powered down to simply start swapping out all the tubes to shot gun it.
i looked down and noticed C101 originally had rivits but i used screws to mount it after i restuffed the cans.

Earlier i kept saying C101 is *NOT ALLOWED* to have a chassis bond directly to chassis?
well i caused it to do just that.
THere is a metal retainer ring in the bottom with lugs that was originaly used to collect the negative sides of the capacitors.   My mounting screws were touching the can,, the screws screwed into the chassis and the heads rubbed / touched the cans thus bypassing all together the Candohm R100. 
I changed the screws out for smaller profile heads and adjusted a few things.

another sorta hard problem to find but i got it only after getting the help i needed to focus on the possible defective area.  Thanks!

new readings:  Does this look any better?
Note the code 125 update says that V1 is to be a 7AF7 so all volage readings will be at least 20v higher than normal.  Right now due to my R102 being 500ohms instead of 300, i think when i move to a 300ohm these voltages are going up!??

Part          DCv across           DCv in        DCv out       comments
R101        22                       21.8            0                Candohm
R103        44                       307             263
R101        81.5                    307             222
R102        41.2                    349             306            supposed to be 300ohm, using 500ohm for now till parts ship
V6-3         --                        300            --                6k6 pin 3 tied to audio output xfrmr primary
v7-3         --                        300            --                6k6 pin 3 tied to audio output xfrmr primary

[jcassity]

i suppose now the R102 gets about 50% less hot than before,, atleast thats the way it feels.

[criageek]

Glad you found the problem jcassity!  Good work  

Rich

[Mondial]

Yes, that's much better. Now you have 22 volts across R100 like you should. 

Have you tested your 6K6 output tubes? They might be a little weak, otherwise they probably would have melted down with no bias.

The voltages will go up with a 300 ohm resistor, but if your output tubes are weak it may not make much difference.

In any case, glad you found the problem and the resistor is not getting as hot.

[jcassity]

i dont know how to test a tube,, other than what i dont have which is a tube tester.
I own a lot of specialty electrical test equip but no scope, sig gen/ tracer or variac ,, nothing common to a radio shop.

while i waited for a response,, i was moving forward to address lack of short wave operation.
i have a light hum in the speaker at full volume and as i rotate the tuner i hear things / noises responding to my rotating the caps.

i poked around to hunt voltages as compared to what chucks / philco schemtics say i should have.
my voltages are oddly high at my last tube the 7AF7,, hard to get to under the band switch assmbly, wayyyyy too high, i believe i need to get it down to 280v.


My paperwork says my voltages should be about 20v higher than the prints with a 7AF7 installed,,, but... right now i have 300v on pin 3 of each 6k6.. going to a lower value R102 will make that much higher,, say in the 330v range id suspect.

I temp inserted a 750ohm resistor for the one getting hot R102, the 6k6's pin 3 went down to about 280v.

I can swap out all my tubes for my new old stock spares and see what happens, not that this will fix the lack of SW band,, but to see if the 6k6's input becomes lower if thats what you would do in my shoes.

sorry , i just dont know what i dont know right now with tube radios, i use to have a mentor on this stuff but he died 10 years ago. back then i had no time to piddle with this.

[jcassity]

Glad you found the problem jcassity!  Good work  

Rich

i found the cause,, i had no idea where to focus on the problem area.,, heck i had no idea there was a problem,, cause  my Broadcast band is working just fine.


All,
SO i conclude that to the earlier much earlier question is that i have about 85ma for current on R100.

[criageek]

I'm having no luck on shortwave either...as well as FM    I also do not have a tube tester, but I bought one off Craig's List this weekend and will go pick it up next week.

Rich

[Mondial]

You don't have to change all the tubes, but I would try installing the new 6K6 tubes and see how the voltage changes across R100. The voltage on 6K6 pin 3 will probably go down and the voltage across R100 up. I would guess to around 25 V across R100.

What pin of the 7AF7 has 300 V on it? I don't have the schematic of your radio so I can't follow.

[jcassity]

i posted it a few posts  back ,, not sure if it was improper to do so since i had to get it from the philco workbench.
you can not use this diagram as a stand alone for any 46-1226 code 125 because there are a lot of big and small changes,, which i posted in other posts... i bundled all the changes into one picture so you see the progression from code 121, code 122 and code 125.

here it is

like pin 7 is supposed to be the shown value but i have 13.5v
Pin 6 is i think ridiing close to 300v..

some voltage readings are very dead on.

what i am going to do later tonight after i finish tilling the garden is start poking around at the internal antenna thing, my L400 to see if i can gently wiggle test to get shortwave to come in.


I had what i felt was an issue soldering a wire to L403,, its like the metal tang moved!  this little bugger is right on the band selector switch so i need to ohm check it as well.

[jcassity]

Rich, since our chassis are very similar,, dont hesitate to give me a call, my number is on post 1 of this thread.

If you need any caps or resistors,, make sure you ask me first,, i think i have like a few thousand,, picked up a tote full of electronics at a fleamarket that came from some repair store that closed doors.  i have too many and will never ever use them all in my lifetime nor will my sons.

just let me know what you need,, no charge


same to you Mondial and Terry, i appreciate the guidance


this is a tiny fraction of my 20$ score

[jcassity]

i just now took the band selector switch out to get at the prior post where i mentioned R300 sizzled a little.,, the white paint marker indicator discolored on me. all this new work is to achieve shortwave reception. I am going to more closely examine the bad switch contacts movement and add No-Ox-Ide to the surfaces. I will also meaure the mica caps for the heck of it.

while i am at it i am checking all of my 7AF7 loktal pins to chassis & will also measure my coils .. didnt do that before cause i didnt think i needed to.

got a few things to do..

Labled the top side of the chassis for the future so my sons will see which item is which.

back at it...............

[criageek]

Thanks for the offer jcassity!  I may take you up on that.  I'm good for now but I'll keep it in mind.  Just picked up a new project this morning (http://www.antiqueradios.com/forums/view...1&t=320701), so I may need some parts for that.

Rich