Motorola ts907 low hv

[timmy]

That’s just it there is nothing I’m finding resistors check perfect it makes no sense I thought maybe something in the convergence but I don’t think there is any high voltage points there to pull it down.

[Yamamaya42]

keep in mind, as stated before , audio output tubes always tend to run hot, as do horizontal outputs, this is just par for the coarse and does not mean there is something wrong.

[timmy]

Ok maybe so but I still have the low b+ and no video and I went over the video amp and output and found nothing I did suspect the 1n60 but I do have sound.

[Username1]

If the sound is clear, and you replaced the cathode resistor, and that circuit seems ok,
then it's time to check the next circuit. It may seem frustrating because there is no
dead short, and everything mostly works, but somewhere you may have a tube
with bad voltages on it, improper biasing, and using too much current.
It will take time to find it, Most likely with tedious voltage checks.

.

[Yamamaya42]

You still have yet to get a decent DVM that has a decent amperage range to check what current draw you really have at L54 right after the voltage doubler.

And until you can do this correctly, as you have stated that the meter you have does not have the range to do so, you are just going on assumption.

GET A decent DVM and check the current at that point to see if it is indeed excessive.

this is an important step.

[timmy]

Going to try something I have been using a 10 foot extension cord to power this tv so with the resistance of the extension cord and the thermistor and using a power cord from a b&w tv very thin and an air conditioner running from same outlet maybe this will make a difference, excessive resistance would cause this.

[timmy]

Well that didn’t work but from the first day I plugged this set in it red plated one horizontal tube and it’s still doing that now only one tube and it’s now looking like the pulling down of voltage maybe in the horizontal the oscillator runs but after warm up plug in again the oscillator will not start again until it sets for awhile and cools down. I don’t know if the yoke would affect the horizontal oscillator from starting. This happened with the old flyback but I since changed the flyback with a nos one. Problem is the voltages across the board are still low it’s not like I can look at voltages and see that one rail is lower then the rest and go to that area b+ low everything is low.

[Username1]

hummmm Red Hot Tube Plates = Too Much Current.

Is G1 for each tube -45V?

Maybe you need to take a break from this tv for a few days......


.

[timmy]

The g1 was low to begin with so I turned it down more like not even a 1/4 up. Took the chassis back out to double check the 2 timing caps .0039 and .0068 it’s always possible I reversed them especially because the print on them is so small I should have used a magnifying glass that’s how small and yes I should get away from it. But only 1 tube, hmm.

[Yamamaya42]

here is the biggest help to know when hor osc is OK.

https://i.imgur.com/afNm19c.jpg

best investment you can make.

[zeno]

Not sure you are checking the right " G-1". We mean the G-1
of the hoz out tubes. They are in // to give enuf output.
Typical sets draw abt 210 ma this one IIRC 240, beyond most
hoz out specs. Thats why 2 HOT's. Others did it in the early days.
Admiral did & if you changed the FBT there were pages to mod the
set to use one 6KD6 H out NOBODY wanted to do them.
If that neg voltage is not there the tubes stay on too long.
See class C amps. !
Once one fries the other takes over. That one will overheat trying
to supply the HV but one cant keep up current demands.
Bottom line is without the proper G-1 voltage you will cook up expensive sweep tubes. Fix that FIRST if needed !

enuf fer now
Zeno

[timmy]

I know but it wouldn’t pay for me since I would use it once then put it in the closet lol ��

[init4fun]

Originally Posted by timmy

I know but it wouldn’t pay for me since I would use it once then put it in the closet lol ��

So after this one your never gonna touch another TV again.... ever ?????

Stop making excuses for not investing in your hobby, screwdrivers & wire snips only go so far.....

[zeno]

I bit rough but.....
We went out to a rib joint last week. I got a full rack & my squaw got
a half. It was a great feed & leftovers I measured my rack & it was
16" long. Next day I finished mine then the next day I took a dump and
it was just a memory. Nothing left but the CC bill.
A nice meter will usually last a lifetime unlike the ribs. Here today, flushed
tomorrow.......
So anyhows get the H OSC going FIRST ! The PS voltages are probably
a red herring.
And YES take a few days off. When we got a dog it got put aside & usually
another tech got it & fixed it fast. That tech was often the shop idiot !!

73 Zeno
LFOD !

Originally Posted by init4fun

So after this one your never gonna touch another TV again.... ever ?????

Stop making excuses for not investing in your hobby, screwdrivers & wire snips only go so far.....

[timmy]

This from the start didn’t do this all the time was random then it was ok now it started doing it again when the oscillator is running I have perfect hv. Maybe it’s because the b+ is low creating this. Only tube I can’t test is the damper.