This is very good looking. Looks like you now have a light weight less expensive
B&K Analyst....

http://videokarma.org/attachment.php...0&d=1666899517

If you apply that signal to the plate of V1 with the coupling capacitor in place
you might be able to pass the signal through the IF Coil A6, it should be tuned
to that IF frequency and pass the signal. Not sure of any other way to be sure
that coil is actually "Good" as far as passing the signal, Even though the ohms
might read ok.....
Other than that, you will have to go through all those parts around V1 to find
the problem.....

Anyway, looks better than I expected. I'm not sure, but it even looks like
that girl may even have red lipstick on, or it's just my wishful thinking....
If there is - well then it's tuned well enough to pass burst signal too....
I would not turn anything till you can get this set working from it's own tuner.....


You know.... I wonder if you took the iF plug from this tv's own tuner, and jumped
it ahead with a coupling cap, to that V2, if you would see the same results....?

It would also rule out the tv's own tuner as a source for trouble......

You guys have done some good work here......


.

Well now I’m going to go over all resistors at v1 and I’m sure the sets own tuner is good because I get the same result from the subber and the tv tuner I don’t know how far off resistors in the IF strip have to be before knocking out the rf signal. I’m sure that coil at v1 is good the wire inside is heavy gauge wire but anything is possible I did measure it and it’s under 1 ohm. And this v1 is the one that sams indicates that pin 8 should be 3.2k but it actually measures 6.3k so I hope it’s a sams typo because there is no reason that I can find why this would be.

Again it will be most advantageous for you to replace the resistors previously mentioned with new 2% or better, as the first half of the IF can't pass a signal.
The cost of doing this will be very low and the gain will be high, don't just rely on DVM testing, the original ones are old and you know there is a fault in this area, so go ahead and replace.

Problem areas include.

L1 47.25MHZ TRAP
L2 39.75MHZ TRAP
L3 1ST Video IF
perhaps
L4 2nd Video IF
As you could feed a signal direct into V2, but not any steps before it.
again, replacing said said resistors could improve thing quite a bit.

Good Morning:

You know, you could possibly try disconnecting pin 2 of L3, A7, same coil, and feeding
that tuner subber signal to G1 of V1, to see if possibly that trap circuitry is killing
your IF signal..... Just be sure your V1 voltages don't change, like possibly G1
changing bias or something...
You might even check that R23 the wiper arm does not leak to ground, or any
other pin for that matter..... You might even try disconnecting that wiper
arm from the L3 coil and see if it passes a signal.......


.

After all that changing all those resistors the pic shows little to no change and the voltage is 97volts on pin 8 so that’s good. When I had the 10k and 2.2k off I checked L3 under 1 ohm. The other L1 L2 are good also.

This is it. Trying to send a pic but won’t go. But it’s the same. Back to square one. I also checked L4 and it matches L5. I wonder if the agc is messing with the signal the video from antenna input in v2 would the agc have affected that because it didn’t or is agc only at v1.

You say voltage is up on pin 8, this is progress, but you still have to isolate the fault, and that will take a few steps, of chassis in/out going by what Squirrel boy suggested.

==
Try disconnecting pin 2 of L3, A7, same coil, and feeding
that tuner subber signal to G1 of V1, to see if possibly that trap circuitry is killing
your IF signal..... Just be sure your V1 voltages don't change, like possibly G1
changing bias or something...
==
If you get a picture when you do this, then L1,L2,L3 are out of tune, if you do not, and still no video when trying to feed to pin 2 of V1 (which should be 3-7v depending an AGC, ) then L4 is likely out of tune.

I have the bottom off the set and turned on it’s side so I don’t have to take it out again. I remember there was 7.5v on pin 2 and I don’t remember if it changed at all with turning the agc.

7.5v on the grid should be OK for V1 to work, if it does, the gain level needed will be much less than was for V2.

Not really ... its square 5001.
Try these: Feed (as usual through a .01 or .001 uF cap) the external tuner to
pin 2 of V2. Does it work?

Remove V1 and repeat ... is there any difference?

Try connecting the input through the usual cap to the pin 7 on the v1 socket ...
does it work?

Connect the input to pin 2of v1. Check the voltage to ground at the cap lead.
(With tube out). Insert v1. Does the voltage change at all? Does it work?
Wiggle v1 vigorously ... does anything change. Try a different 6EH7 ... does anything change, with wiggling.
If its close quarters, attach a thin bent wire to the probe tip to reach the pins.

Disconnect the wire to pin 2 of L3, everything else the same. Does it work? Is the voltage at pin 2 of v1 the same? Check voltages at each and every terminal of
L1, L2, and L3 ... all should be the same. This takes a high impedance voltmeter.
IF there is any picture at all ... does it change differently as you touch different terminals.

Finally ... have you checked that each and every pin of v1 is in fact making
a connection to a wire connected to that pin? By that, I mean actually touching
a probe to the pin itself, with the tube pulled a little out so you can reach the pin ...
and wiggle the tube. Of course, a tube extender is better.

The picture posted yesterday was when fed into the grid of V2, but there was nothing when he tried the same on V1, he has not tried the plate of V1, however, but he is going to try again with the grid of V1 unhooked from L1,L2,L3, But I suspect the problem is L4 :(

I don’t know there’s something else wrong here L42 keeps getting so hot it’s falling out of the holder that it’s in this is definitely not right the wire on this coil is like hair and if it breaks I’ll have even more headaches unless I find out why.

Maybe there’s something going on with k1 that I made all resistances seem to check out ok but I’ll probably put the original k1 back in because the k1 is agc and tied to all of this madness.

the hot coil problem is most likely due to a faulty C96, But you can't get the exact replacement for it, it may even be what burned r145.

it can be replaced with 2 caps in series,
https://www.mouser.com/ProductDetail...rjw6zMJw%3D%3D
https://www.mouser.com/ProductDetail...EPCXzdjw%3D%3D

this is unrelated to K1
2 3kv caps in series that = 6kv@132pf total

get 2 new 1000v 2amp power diodes at the same time.

C96 is a 130 6kv it’s new I still have the old one. Yet in the pic the other day the focus was good unless this cap is leaking I don’t know. I was able to get a new one from moyers.

Not really square 1, or square 5001. You are making progress......


I was just looking at the schematic & thinking about the hot focus coil too....
But I was wondering about the other part of the circuit....... You know, the
part over by V1 where there has to be a rotten nut.....

I'm wondering about C60, & R87, & R14. At this point any Variable Resistors
should be checked from all 3 pins to ground for a possible internal short, not
just checking to be sure they read their rated resistance.... I still did not see
a post about R23 to be sure there is no short to ground from any of it's pins...
Think about that "tin wiskers" stuff inside these pots.....

Any way poor Timmy being pulled in 30 different directions to check this, and
replace that..... I think he needs a beer....... And if he ain't drinking yet
well then he's a strong determined individual!

The other bad bunch-a nuts can be hiding in that V6 area, where this focus
pulse is going - See that pin 3 with 2.5V on it, and with the scope pic of that
450V P-P wave.... No way you going to be able to figure out what should
really be there..... And that little circuit helps that K1 do it's thing, and it's
attached to V1, or did I say that once already.....


.

unless there is some other weird error in the way the flyback was wired back up, I'm not sure what is going on here.

The agc pot checked already for anything and r23 didn’t check yet but the 2.2pf+25 cap I actually have one coming. And yes I know the agc network is hooked to v1 so with L42 and focus coil getting hot there’s the 2.2pf cap and the 130pf hopefully one of these is the cause.

Flyback is good I went over that.

I would also think that C59 would be suspect, its getting hammered with pulses from the flyback.

DANG this set is REALLY an oddball one!
:scratch2:

I still have the original 130pf 6kv and I have a 470pf 2kv and I have a 2.2Pf +25 pf 1kv coming sams don’t show a voltage for the 2.2pf I hope this cures L42 from getting hot that is very delicate.

Disconnecting the 470pf and 2.2pf made no difference L42 still getting hot and made no difference with video the 22ohm on v1 was 28+ohms so I changed the 22ohm on v2 it was 26+ohms on since doing this I don’t have the good video I had on pin 2 of v2. The batteries are at 8v maybe the subber is not working at full because of that. As for L42 all I got left is the focus coil or the 130pf 6kv cap which is new so I don’t know what’s more likely.

Has that big dropping resistor network been changed? r142-144?

Are you referring to k1 ?

I did not think that those caps in the sync/ AGC area had anything to do with the L42 heating problem, you unhooking them just confirmed that, the way they are doing things in this set is confusing to say the least, BUT, the current path for L42 has to be between pin 1 of the flyback and pin 8, and also the resistor network to ground.
But what is really going on here is odd.

i mean the 3 big 22 meg 2 watt resistors in the focus circuit

Yes they are new along with the 130 cap

So I could have probably used the one single 66 meg focus resistor that’s used in the ctc series clone chassis and rca.

yes, they are sill to be found all over the place.

But can that single 66 meg be used in place of 3 22 meg resistors. Why Motorola used 3 resistors when they could have used one. I have a bunch of those resistors.

yes, the big 66 HV ones are much better in this case than small ones cause they were made just for such this task, and multi small ones have to be rated 2kv each or higher, its much easier to get a big 66 meg 6kv one, as they are all over the place.

When I changed those 3 22meg resistors I just got 22meg 2 watt resistors I didn’t specify 2kv rating does those pose a problem of any kind. ??

It stands to reason that they should be, you have 4-6kv on one side, ground on the other.

they may have used the 3 22k ones for Creepage and clearance for high voltage reasons.

but at any rate if they are not rated for 2kv, they may be a source of trouble.

22meg @ 2w 2kv seems to be unobtainium, so you are better of with a big 66m 6kv one.

I’m going to put the single 66meg resistor in but if the resistors I had put in are just ordinary 22meg 2 watt resistors then is it safe to say they were passing excessive voltage to ground. After all there is 4-6 kv on them.

I dont get why sams don’t list certain resistors like the 3 in the focus circuit.

Reading that I don't think you understand how ohms law or resistor voltage ratings work. The same 6KV will be across those 3 resistors regardless of their voltage rating. Resistors don't pass voltage, they pass current and that too wouldn't necessarily change with voltage rating.

The voltage rating on the resistors is the maximum Voltage that you can put on the terminals and expect voltage to not cause arcing across the terminals....If it arcs it probably will do so noticably, and if it arcs it will pass current NOT voltage.

Tom: I don't believe that arcing across terminals is what really determines
voltage ratings of at least carbon composition and possibly metal film resistors.

The reasson is that for a given voltage rating, terminal strips of the same outer material of the same spacing have higher voltage ratings. For a given size (spacing) epoxy transistors and diodes have enormously higher ratings.

I suspect that for carbon composition reststors the voltage rating has to do with possible internal damage due perhaps to tracking. In any case, experience says that the actual usable voltage for one and two watt carbon composition resistors of high resistance starting about 1947 or 48 is enormously higher than the ratings. The two watt ones easily take 2 kV.

I've used 2 watt 1 meg carbon resistors pulsed to 2.5 kV run continuously for months and on and off for 20 years with zero failures. Ditto for 1/2 watt resistors at 1 kV. One circuit generates 20 kV pulses with 800 pS rise times using 22 series connected ordinary transistors (yes, all one type and all only two near-sequential batches from one manufacturer) in avalanche mode with the bases driven by pulse transformers with resistor bias networks. The pulse rate was up to 10 kHz. I was stupefied when the idea worked at all, but after 20 years with zero failures in numerous systems .....

They ran continuously to keep the temperature constant as they were driving crystal polarization rotators that needed to keep the resonant frequency constant to better than 0.5 ppm (and rotators, while being quartz just like radio crystals, are an abysmally bad temperature quality cut).

I figured Timmy was talking about modern carbon film resistors which probably are less resistant to arcing than the old carbon comps. I doubt he would be as likely to look up the voltage rating on a period part as he would a modern replacement being considered.

It makes sense the old carbon comps would have better resilience against over voltage since there's a nice straight path between the terminals unlike some of the film resistors now that have a spiral which can potentially arc between adjacent tracks and or the terminals.

Either way, there has to be SOMETHING causing the peaking coil L42 to get hot, and I had serious doubts that it had anything to do with the sync / AGC area (C59,C60), him unhooking them confirmed this, so it has to be something with the current path in the flyback transformer pins 1 & 5, which also includes the resistor net to ground off C96, there is no way to know if the 2w ones he put in there are not up to the job, but there is no way to know if they are as well, but if he does have a 66m 6k resistor that's made for just this situation, best to try it and see if it helps. :)

Actually I was talking about the modern resistors not the old ones