they are part of an RC, circuit yes.

very delicate, the slightest touch can change it,

I would think it’s not likely that both would go bad at the same time. These resistors are heavy wire wound I have never seen one of these rise in tolerance.

3w resistors are rather cheap now, and much smaller and run cooler than in the 60s, replacing them all won't cost much more than $10, and make SURE 100% that it's not a resistor problem, which is a good thing to do before looking at caps IMOH.

Same as the 2 .001 caps what’s the likelihood of both of those caps being bad. They are ceramics and I’m surprised that it wouldn’t be mica caps in such a circuit.

Ceramics almost never fail and when they do it's usually in sweep circuits where they're being whacked with several KV worth of pulses, not <300VDC and <3VAC that the IF subjects them to...

If you are concerned about the ceramic caps in the IF leaking current I gave you great advice before... Temporarily stick a cap 100X the capacitance in series. It will stop DC leakage and the series capacitance will be almost exactly the same as the original part alone.

The bulletproof-ness of ceramic caps is a fact. The only defective one I ever encountered was inside the motor of a cassette player. The complaint was sporadic overspeed. The motor had a 3-segment commutator, with 3 tiny ceramic caps bridging the gaps between segments. One of the caps was leaky, and replacing it cured the speed problem.

Since you stated that the voltages on pins 7-8 of the V1-V2 are wrong, but the 6EH7s are NOS, and the problem is not a bias 275v problem and extremely unlikely to be disc cap related, then once again the best path is to replace the power resistors, no matter how they seem to check out.

List here.
main power diodes
https://www.mouser.com/ProductDetail...2B4kkscA%3D%3D

6.8k 3w (r40, r49)
https://www.mouser.com/ProductDetail...0BKWoLFQ%3D%3D

2.7k 3w (r41, r50)
https://www.mouser.com/ProductDetail...Wwtn4Z2Q%3D%3D

8.2k 3w (r39 , r48 )
https://www.mouser.com/ProductDetail...2a7TUHog%3D%3D

Yes, use all 3w resistors, they will be smaller then the ones replaced, and much more reliable.
In fact replacing all resistors in the IF may be the only way to get it working again, and even then, you may not be able to.

When using the ohms chart for tube sockets use with tube in or out.

tubes in, but it does not really matter much, since only the heaters will alter the readings you may be taking, which will be low anyway, so if you do it tubes in via a test socket under the tube, or out, just probing socket alone, you should get same readings.

I’m getting a really bad reading on pin 8 of v1 should be 3200ohms 3.2k I’m getting 6.30k I figured I would check resistance on v1 and v2

It starts at 5k and slowly rises to 6.30k

You are aware of the note “measured from the output of X2” that would be the cathode of the diode, before L54, and not ground, if this is what you are doing, then it's a good sign the power resistors are bad, but if you are measuring from ground, your readings are wrong.

The reading starts at 5k and rises slowly to 6.30k while it should be 3200ohms 3.2k

No I’m not measuring from ground I’m on the second diode which would be x2 output

Then, that seems to point right at the power resistor networks I pointed this morning, replace all the 2-3 watts in the area, and the power diodes, cost from mouser, 10-15$

I’ll post the other resistance readings from v2 v3 because they are way off

As it has been mentioned before, by myself and others, your best hope to get this working is not to touch any capacitors in the area what so ever, and VERY CAREFULLY replace all resistors with 2% or better carbon film types, paying close attention to placement and lead dress, IE, try to make it look as close to the original as you can, and since technology has changed so much over the years and they have gotten smaller, it never hurts to go up one size in power rating, cause even if you do, what you are putting in will be physically smaller than what you take out, they are that much more efficient than the old ones.

Ok v2 and v3 are within good range only v1 is a problem
The only pin that’s not right is pin 8 should be be 3.2 but it’s measuring 6.30

R39,R40,R41 obviously, get all 3 in 3w, but I would not stop there, you should have R48,R49,R50 on hand as well in case. It would not hurt to change R22 as well.

Did you measure from output x2, like it says in the note? :scratch2:


Edit
Never mind, I responded to an older post,I missed a page!

jr

I already asked him about that. :D

R22 is a trap

my error, that's R38, I jotted down the "22" next to the right number! :P

I will tell you I have the chassis out on the bench but this circuit should do what it has to on the bench and I put an antenna input and the voltage goes up very little so it’s resistor time I doubt it would have made any difference it it were in the set at this point

Ordered the resistors but I’m wondering where the 7 volts is coming from on v1 pin 2 it’s almost like the tube is locked on there for pulling the voltage down on pin 8 where on this tube is there something that would make it conduct or turn on full or partial.

I’m having a hard time believing those power resistors are bad because if they cannot supply the 100 v to pin 8 but only 60 v then I would think they wouldn’t be hot like they are working hard that’s why maybe the tube is partially on maybe not full but like an idle.

If I pull v1 the voltage go way up on v2 pin 8 but v1 pin 8 voltage stays the same low.

R 39,40,41 form a voltage divider, your resistance check of pin 8 found a problem with it, so replacing all 3 is the next logical step.

I don’t understand why the ohms go up slowly from 5k to 6.30k why slow it’s like it’s filling a cap. There is the one resistor that goes to ground and I hope something is not grounding that is not supposed to be. And I have new 1n4007 diodes I had put in and made no difference.

On the Motorola it has 2 rectifier diodes is 1n4007 ok for this or is there supposed to be a fast recovery or anything special about these diodes.

the 1n4007 is a very old common diode that SHOULD work OK in the set, that is if you have a real one...

Problem is, over 60% of the ones out there are counterfeit junk and should not be used.

In fact, a few years back, we scrapped an entire lot of thousands of them cause they were all junk.

general rule is, anything not got from Mouser or digikey is not to be trusted when it comes to semiconductors.

as mentioned, a good choice is, https://www.mouser.com/ProductDetail...2B4kkscA%3D%3D

I bought a bunch of 1n4007 diodes but they look cheap so I’m not going to use them but I did try them they did work and like the output diode getting hot so did the 1n4007 also got hot so I put back the originals. So maybe it’s fine since trying to see what the ma was and it only showed 550ma so it’s not loading up.

What I find odd is with the resistors off pin8 there’s 138v and at the same time there is -7v on pin 8 and just touch the resistors to pin 8 and drops right down to like 63v where is this -7 volts coming from.

This is not unusual, take a look at any given tube grid that is not pulled high to bias on a schematic, and you will note that they tend to have a negative voltage on it, so it stands to reason that if you float it, it will go negative.
Examples.

pin 2 V10B , pin 9 V12A

Well so much for the resistors they made no difference I kind of had a feeling the old ones were not bad. there is 132v there but soon as putting it on pin 8 it drops to 63v so something is going on here that I’ve yet to figure out. On v1 pins 1&3 are 15v and pin 2 7.25v it’s like the tube is locked on full pulling the 132v down to 63v. So I lifted the power on pin 8 it’s not the tube pulling the voltage down pulling the 8.2k ground drops the voltage. Then with the ground off I get the proper ohms.

Hi!

Sorry, Our crappy internet service was off for several days.... If you have 15V
on the Cathode of tube V1, 6EH7 the 1St Video IF, then I would be wondering
what the plate voltage is? is the 275V source right, and is it 275V or lower?
Also what id the voltages on each side of R38, a 22 Ohm, R44, a 47 Ohm,
and R45, a 560 Ohm. Also what voltages are on both sides of R37, a 2.2K Ohm?

Please make these readings with everything hooked up.
Also are your power supply voltages back to what they should be?

.

V1 pin7 193v
R38 14.92 14.35
R44 13.26 14.43
R45 13.45 0
R37 7.70 7.66
The 275v is around 280v other voltages are good on the ps. It appears that once the 8.2k goes to ground the voltage drops don’t have to be on pin 8 for the voltage to drop.

things to try.
swap V1 & V2 and see if voltages change.

resistance check of L4

pin 3-2 4-1 3-4 1 - gnd 2 to gnd.

Under 1 ohm swapping tubes don’t do anything I think there is something at ground pulling this down. This testing I’m doing with the tuner plug out chassis on bench tuner plug looks like it would not affect the voltage at pin 8.

If I knew the test path for resistance check I could probably find what’s happening here pin 8 to x2 output.