Well the 66meg is in place and the L42 is still getting exceptionally hot all that’s left is maybe the focus coil or can the coil even cause this L42 to get hot I’m sure it gets warm under normal conditions but it’s way to hot.

does it still get hot with the 1V2 removed? :O

I was going to say if the 1v2 is shorted which I doubt or the 130pf is shorted which is new cause this.

1v2 out still gets hot but with it out the screen bearly lights

That is normal for no focus bias.

This leaves only 2 things, problem with the focus coil or L42 or something weird with the flyback transformer.

The path is from pins 1 -5, if the focus coil was somehow not resonating correctly, L42 would take the hit for it, or if somehow pins 5 &9 on the flyback were swapped, then focus coil/L42 would be overloaded.

Not really sure what it is here, this is a weird circuit.

It appears correct at the flyback 9 is horz centering that’s right and pin 6 is next to pin 5 and it’s right to the focus coil. If the ohms are correct the coil could still be bad ? The voltages 640 and 770 are at the right locations.

Pin 8 v6 should be 230v normally but as it stands it’s only 160v if something is not conducting in that tube maybe this is the voltage buildup I have the new 2.2pf cap just a thought even though I disconnected it before it won’t make a difference if the cap is bad. At this point I don’t know if I should put the old k1 in even though the resistance’s are not right unless I screwed up the one I made I don’t think so but never know all this is tied together video focus voltages.

The heating of L42 is unrelated to K1 or the state of V6, working or not, this was verified when you took C59/C60 out of the loop and it had no change on the heating of the coil.

So it has to be local to the FBT, focus coil and L42, but not the 1V2.

I don’t know where a problem could be at the flyback I checked all the connections I didn’t want to miss anything at the flyback. Would a damper have anything to do with what’s going on here. So I wouldn’t think the 130pf would be bad.

Not sure what is going on here, I do not think it's the damper, could be C96, but not sure what unhooking it may do, the way they have this set up is strange.

That’s Motorola for you they had to be different

Guess I’m at a standstill.

Well I haven’t had a decent picture to set up the focus but I found that when the slug is out to much L42 seems to gets hot faster but when it’s in further it takes longer to heat up again I’m sure it’s supposed to get warm under normal conditions so until I get a good picture to focus I’ll leave the slug in more for now. So now I have to figure out what to use to keep the coil in it’s holder hot glue may not be good enough.

Epoxy?

Well I want to make sure it can dissipate heat rather then trap it in. If the temperature don’t exceed the melting point of hot glue then it’s good.

Hot melt is a bad choice for holding such a coil, as it will get soft as it warms.
Better choice would be MG Chemicals - 8329TFF-25ML 8329TFF , thermal epoxy. $21
or silicone type 2.

Ok here’s what’s happening now the 770v tap is off the 640v tap but to make 640v it goes through a 47k but L42 is tied to the 640v tap befor the 47k at pin 1 on the flyback so there is almost 780v on both sides of L42 so I changed the focus coil it did nothing infact I had the antenna on and again it flickered clear and almost instantly L42 and focus coil got super hot. I don’t know what’s going on here I thought I had it with the position of the focus coil but something seems to be getting in the 640v tap I don’t know.

The boost tap is pin 7 (should be) , L42 is pin 1, which is on the bottom of that winding, so there should not be boosted voltage at L42, but only the base bias that's fed to pin one.

What you may want to do is double check the resistance of that winding.

.8 .5 .45 & 9 ohms for each taps .

Yes pin 7 is for the most part pin 1 they are so close they should be the same there’s nothing between 1-7 that shows.

Incorrect.

It just looks that way due to artifact errors from the poor scan of the schematic, pin 7 skips over 1 & 2 and connects to the 3rd tap of the winding only, just under where pin 5 is.


it should be .5 ohms from 1-7.
or so it says on SAMS.

Flyback should be ok because it is making 640v and 770v so where is something crossed. Omg this set wow.

Without warm up just when screen lights up the 640v is 605v and the 770v is 760v didn’t check ohms yet but this looks ok I tested at the 10k and 47k.

Could the horizontal frequency be off in such a way that it would generate higher voltages and still be able to lock into video.

Not likely, if the horizontal frequency was off, then there would be no video lock, horizontal AFC and sync control will bring it into range for it to lock into the incoming video, but it has to be within the right frequency range in the first place to do so.

Something else is going on here, at this point, you may try to unhook one side of C96 to see if that has any change on the heating of the coil.
Can't think of anything else right now. :O

None of this makes sense one leg off c96 coil gets hot I don’t know where this coil could be getting a ground to heat up like this. It can’t possibly be designed this way that it would get this hot and I believe this may have something to do with the video in some way or another.

if you have not already, make sure R145 is still = 100K OHMS.

Yes checked r145 it’s still good so I’m thinking maybe overall this coil is supposed to get hot can’t see any other reason it’s getting hot it’s hard to believe that the coil stayed in it’s holder all these years with some kind of antique glue they used and now it’s falling out. I’m probably going to remove it and use hi temp silicone maybe it will stay in this time. If it burns well then i know that it’s 35ohms and 3600uh and hope I could find another if I need it.

This is L42 the coil itself is big compared to others in this tv.

The coils still look OK.

This is a bit costly, but should work.

Find a ceramic heat sink NOT metal, that can be glued to the coil, big enough to do it some good, small enough to fit under the chassis, use thermal conductive epoxy to stick it together, making sure the epoxy touches both the coil and heat sink.

Once cured, it should run cooler.
https://www.amazon.com/MG-Chemicals-...Q%3D%3D&sr=8-3

example
https://www.walmart.com/ip/Whigetiy-...erId=101180981

There is absolutely no room for anything other then the coil lol �� I have 500 degree silicone.

you can get a small ceramic heat sink

Problem now is the coil measures 55ohms it’s not 35 ohms anymore so I guess it’s not supposed to get this hot more heat more ohms.

I have a Motorola book with a schematic note the500vpp pulse negative and positive where do these come and go.

Better picture. I had taken the focus coil out to change the horizontal centering pot but I took a picture of the coil so I wouldn’t put it back wrong so I know by the color of the wires it’s right. I can’t for the life of me find C3-C power supply cap I’m just checking if I maybe hooked it to the wrong source.

https://www.amazon.com/Ceramic-Cooli.../dp/B07VH3F9SQ 1/2 inch in size should fit nicely any replacement coil will be unobtainium, protect what you have while it still works, put a ceramic heat sink on it.

Right now I’m not going to plug this in until I can find C3-C capacitor to see where it goes because according to the Motorola schematic the L42 should only have 500v on it but I’m testing it has around 780v so I need to find where this cap goes maybe I placed it in the wrong place. This extra voltage on the L42 is not good I need to find out why.

Incorrect. :(
the Motorola schematic is referring to the tie points on the flyback transformer, It's saying + and - 500v PP as in Peak to peak, that is not to be read as DC voltage ref to ground.

stick with the SAMs.
It's less confusing! :yes:

That Motorola schematic has some good additional information on it.... It would be cool
to know if those voltages are there, and correct. I was wondering if the focus voltage
is correct, and in the range that is printed on the Sams.... Can you turn the focus
coil and have a range of 4.3KV to 5.2KV ? I know with a HV Probe you will not
see much resolution, but it may tell you if things are OK enough to not
worry about that part of the circuit. Not sure how you would check
that Plus & Minus 500V P-P - I guess you can give it a try
with DVM and see what happens......

Also for L42 getting hot, you know each coil & Cap are a tuned circuit, If there is something
wrong, it may be peaking at a poor point and creating too much power.

All I can think of right now would be to check focus voltage as best you can.
Since the flyback was removed, it may be a good idea to try and see as best you
can that the pins that go where you think they go have the right resistance on
them as best as you can determine.

Take a picture, several pictures, of the flyback wiring, then disconnect all the wires,
measure the resistance of all the pins as you see them using both schematics, and
try and determine if it's wired correctly. You may also want to check resistance
from one isolated winding to another, This confirms no short between windings
and that they are wired correctly inside the transformer.... Since you have 2
Flyback transformers, you can compare between the two.....

My thinking is that since that flyback has pins that are tied to components and then
back to other parts of the flyback, that if a wire is not connected right, then voltage
may be fed to, or from one section out of phase, and causing problems, possibly
even heat on L42.

Does the flyback run hot?

I'm not sure I would switch any wires unless you have real good cause to do so,
you don't want to make anything worse....

With that coil measuring a higher resistance, it may be because it's been hot, and
starting to change because of that.... Or since there are differences on the resistance
measurements of some coils from one schematic to the other, it may just me
differences in their test equipment, or component tolerances.....




.

Before I had put the old flyback back in I checked resistance on it and it was very close for an old flyback. I do know the ohms are going up on L42 because of heating up. The flyback is cool no heat there. I had went over all the flyback connections several times they are good. I had a new flyback but it turned out bad so I put the old one back in. As for L42 I have to worry about that coil if I can’t get one if it burns I’ll have to check focus voltage.

The focus voltage is perfect and adjustable to sams specs. But the 6hs8 v6 has questionable voltages on 3 and 6 3 should be 2.5v but it’s only .3v and 6 should be 145v but it’s 111v and these pins have the 470pf and the 2.2pf caps these I think are for feedback and it don’t look like it’s doing anything otherwise the agc would probably work and I would have video. I question this because both caps have a wire one to L42 and the other to the focus coil so if these caps are not conducting in the circuit this could be affecting L42 and killing the video it’s all tied together.