Motorola ts907 low hv

[Yamamaya42]

but do check the coil, if you have not yet, especially resistance between the windings and the windings to ground.

[timmy]

Originally Posted by Yamamaya42

but do check the coil, if you have not yet, especially resistance between the windings and the windings to ground.

Then I have to cut all the connections the coil is wrapped on a plastic bobbin if I check resistance with connections on it will seek ground but with connections off there is no path to ground. The only ground is the .001 to ground I checked already.

[timmy]

Ok here’s what I came up with weather or not it turns out to be true I don’t know yet but obviously there is something invading the negative side so if it were shorting it would trip the breaker or burn the fuse wire so I’m thinking it’s something with cushion like a .1 or ,01 some or any cap to ground that is starting to short like the 2 in the power supply one on negative and one on positive there are 2 .01 caps there and several others I haven’t changed. After all the positive output diode is getting very hot and this is not right my other Motorola diodes never got hot it was a 908 chassis.

[Yamamaya42]

Originally Posted by timmy

Then I have to cut all the connections the coil is wrapped on a plastic bobbin if I check resistance with connections on it will seek ground but with connections off there is no path to ground. The only ground is the .001 to ground I checked already.

you dont have to cut anything

http://suzaku.live-evil.org/resist111.jpg

measure the resistance between pin 7 of V1 and pin 2 of V2, it should test very high, if not infinite in resistance.

That is the most important thing to test.

[timmy]

Originally Posted by Yamamaya42

you dont have to cut anything

http://suzaku.live-evil.org/resist111.jpg

measure the resistance between pin 7 of V1 and pin 2 of V2, it should test very high, if not infinite in resistance.

That is the most important thing to test.

It measures 23k and those coils did measure.1 ohm each.

[Yamamaya42]

Originally Posted by timmy

It measures 23k and those coils did measure.1 ohm each.

seems OK, for reference, the same test on L5 should test about the same IMOH, if there was a coil short, the reading would be low.

[timmy]

Originally Posted by Yamamaya42

you dont have to cut anything

http://suzaku.live-evil.org/resist111.jpg

measure the resistance between pin 7 of V1 and pin 2 of V2, it should test very high, if not infinite in resistance.

That is the most important thing to test.

Originally Posted by Yamamaya42

seems OK, for reference, the same test on L5 should test about the same IMOH, if there was a coil short, the reading would be low.

So what do you think of the idea of a cap being a cushion.01 ?

[Yamamaya42]

Originally Posted by timmy

So what do you think of the idea of a cap being a cushion.01 ?

or that 800pf?
but if it is one of those, as mentioned the alignment will be disrupted if replaced, so damned if you do or don't it seems.

your best way forward may be to rig for direct video input.

[timmy]

Originally Posted by Yamamaya42

or that 800pf?
but if it is one of those, as mentioned the alignment will be disrupted if replaced, so damned if you do or don't it seems.

your best way forward may be to rig for direct video input.

I don’t think it’s the 800pf because there is no power source with it removed from pin 8 as long as the 6.8 is connected to the 8.2 and then grounded that’s when the voltage is lost

[Username1]

Hi

I believe measuring resistance from one side of the IF Coupling Transformers, or IF Coils
is not necessary, and you can achieve better results measuring voltages, like for example
Pin 7 of V1, and and Pin 2 of V2. If the Primary, & Secondary had some short, or leakage
it would show itself with 200V on one side, if the insulation were to break down at the
200V operating voltage it would show on grid of V2, and be more telling.

I'm wondering what the voltage on pin 8 of V2 is...? They are almost the same circuit,
and with almost the same voltages on all the same tube pins......
Same resistor voltage dividers too......

I'm also wondering if these voltages are a result of no signal from the tuner....

Have you tried hooking up your tuner subber to this tv & putting a signal on it
and leaving the tuner power plug hooked up to the tuner, but just removing the RCA
plug to the IF, & putting the Tuner Sub box in..... And then measure these voltages...?

.

[timmy]

Originally Posted by Username1

Hi

I believe measuring resistance from one side of the IF Coupling Transformers, or IF Coils
is not necessary, and you can achieve better results measuring voltages, like for example
Pin 7 of V1, and and Pin 2 of V2. If the Primary, & Secondary had some short, or leakage
it would show itself with 200V on one side, if the insulation were to break down at the
200V operating voltage it would show on grid of V2, and be more telling.

I'm wondering what the voltage on pin 8 of V2 is...? They are almost the same circuit,
and with almost the same voltages on all the same tube pins......
Same resistor voltage dividers too......

I'm also wondering if these voltages are a result of no signal from the tuner....

Have you tried hooking up your tuner subber to this tv & putting a signal on it
and leaving the tuner power plug hooked up to the tuner, but just removing the RCA
plug to the IF, & putting the Tuner Sub box in..... And then measure these voltages...?

.

V2 is not the same with the voltage divider the 8.2k on v1 goes to ground but the 8.2k on v2 does not go to ground that’s the difference the ohms check perfect on v2 but v1 the only pin that was wrong was pin 8 and I have tried with the tuner plugged in and out with the subber and the voltage only went up like 4 volts. It’s something on the ground pulling the voltage down take the 8.2 off ground and voltage is good and also the x2 diode getting really hot not right. Iirc pin 8 was little higher then what sams says. Again pin 8 v2 don’t go to ground like v1 does.

[Username1]

Hi

Timmy, I understand what your saying about the 8.2K resistor. I Don't see any reason
for it except possibly biasing, or absence of signal from tuner.... If pin 8 on V2 has
100V on it, or 63, I'm just wondering what might be going on there that's all....

I don't have a good idea at this time for what you have now.... As for the hot diode,
if the power supply voltages are normal, I'm not sure I have an idea about that....


.

[timmy]

Well maybe I’m wrong completely about the voltages all pins hooked up pin 8 v1 63v v2 pin 8 55v maybe the voltages are supposed to be that until it conducts then it becomes 100v. Maybe it is a biasing problem I did check current with the resistor to ground versus not on ground and ma only went up 1ma with resistor on ground so I guess it’s safe to say it’s really not shorting.

[Yamamaya42]

As for the hot diode, if you have the replacements in there, as i pointed out before, there is a good chance they are counterfeit diodes, do not rely on them.
like seen here
https://www.eevblog.com/forum/projec...e-real-1n4007/


It would not hurt to put in 2a diodes like these,
https://www.mouser.com/ProductDetail...2F4Otccg%3D%3D
they WON'T get hot on you!

[timmy]

Originally Posted by Yamamaya42

As for the hot diode, if you have the replacements in there, as i pointed out before, there is a good chance they are counterfeit diodes, do not rely on them.
like seen here
https://www.eevblog.com/forum/projec...e-real-1n4007/


It would not hurt to put in 2a diodes like these,
https://www.mouser.com/ProductDetail...2F4Otccg%3D%3D
they WON'T get hot on you!

Originals are in the chassis.