Motorola ts907 low hv

[Yamamaya42]

Att Timmy!

http://suzaku.live-evil.org/1011221837.jpg

This Mostly OK working oscilloscope can be YOURS for the price of shipping + a probe that you can get on amazon!

all you have to do is PM me if you are interested!

[Electronic M]

Originally Posted by Yamamaya42

Att Timmy!

http://suzaku.live-evil.org/1011221837.jpg

This Mostly OK working oscilloscope can be YOURS for the price of shipping + a probe that you can get on amazon!

all you have to do is PM me if you are interested!

If I still had the spare scope I sold a few years ago I'd have made the same offer.

Out here good Scopes can still be found at swapmeets and hamfest for $10 if you keep an eye out long enough.

[timmy]

I don’t understand why if v6 is pulled out the horizontal oscillator won’t run but put it back it runs but still low hv so I guess this whole crazy problem is between the horizontal oscillator and v6. If there is something interfering with the oscillator then it looks like only 2 areas pin 13 from the flyback and pin 9 to the sync amp.

[Yamamaya42]

Again, given the limited tools you have on hand, it's very unlikely that a complicated issue like this can be worked out.

It's like trying to play Jenga on a crooked table with your eyes closed.

Vertical sweep is dependent on the boost from flyback transformer, so that has to be working, high voltage is dependent on horizontal oscillation being correct and at the right frequency, amplitude and waveform, and if it's NOT , the horizontal output tubes can go into oversaturation, overload the power supply and rob power from critical systems, like the horizontal oscillator.
Or, something that controls the horizontal oscillator can be in play here, the signal shown on pin 9 of V12 is key to timing and control of the horizontal oscillator, generated by V10, I'm not sure what effect the removal of V6 has on V10, but the signal path goes that route.

But as I and others have been saying, with just DVMs, you will be very unlikely be able to crack this nut.

[timmy]

The 6bk4 has got a light blue color inside and pin 5 is 245v and pin 1 is 400v sams says both pins should be 360v and adjusting the hv pot don’t bring up the voltage on pin 5 maybe this is holding the hv down got a new damper in. And tried another 6bk4

[Yamamaya42]

A blue or green glow from a 6BK4/A/B/C is normal, it just means that you are getting a good dose of x-rays, and it would be advisable not to get angry at anything, unless you want to suddenly turn green, increase muscle mass by 300%, rip up everything you are wearing, and terrorizing everyone near you by grunting and growling at them in a primeval nature!

As for not being able to adjust the HV, if it was low to start with, this could explain why adjusting R11 has little or no effect, a test you may try is to REMOVE the cap from the 6BK4 and measure the HV at the point there, this disables HV regulation, so be careful not to let it arc.

If there is no significant rise in HV with the cap off, then the problem is not the regulator, but if it does go up, 22-24k or more, then it is the regulator, if you do see a rise in HV, limit how long you run it with the regulator disabled, as it will stress parts over time.

[timmy]

Ok so I have the chassis out again and I tried taking the cap off in the set 20kv no higher I have the yoke plugged in on the bench waiting a few minutes to warm up both boost voltages are there tried 3 rectifier tubes just won’t go above 20kv cap off or not again subbed some tubes nothing make a bit of difference the other voltages that we’re dropping don’t anymore since I wait for warm up. I even tried the 0039 and 0068 caps the old ones which are good still. The 140 at the hot is around 160v and the oscillator tube is still giving voltages that are to high 6 and 3 are 165v.

[timmy]

So if the frequency of the horizontal drive is off besides resistors, capacitors, tubes, horizontal coil, which tests at 85 ohms what else is there to look at maybe the flyback.

[Yamamaya42]

The frequency and amplitude and shape of the signal has to be right. Example, if the sign-wave at pin 2 of V12 is wrong, then the signal at pin 5 of the horizontal output tubes will not be correct, also, if that signal is not aprox 150v p-p, HV & sweep could be low.
Also, if the signals in/out of V12 are nor right, there could be a problem with synchronization.

[timmy]

So how is synchronization done when everything around this area is ok.

[Yamamaya42]

Phase-locked loop controlled oscillator.

Keyed off the sync pulses of the incoming video signal, shaped and processed by the SYNC SEP & SYNC AMP and passed on to the VERT MULT & HORZ AFC respectively.

However both of these have the ability to free run w/o need of control input in a randomized mode.
But in your case, horizontal section is having a problem doing this, there could be any number of things causing it, a resistor or capacitor that does not sit well with the circuit, even if they test OK, the wrong types can upset things, as been mentioned , it's a tuned circuit using feedback including the yoke, and the FBT, it's very easy to make it unhappy. Especially with dual horizontal output tubes...

[timmy]

I had mistakenly reversed 13 and 14 on the flyback and that’s where the bars came from I since made it right and the bars are gone so I don’t know if this has something to do with this hv problem

[timmy]

I’m going back at what I did I originally took the old flyback out and put the new one in and all was fine only no video then I thought maybe the fly was defective and put back the old one that is when I reversed 13-14 then put the new one back in again with the mistake on those 2 wires and had the bars but since fixed that and this is what I’m left with low hv.

[Yamamaya42]

That would have introduced a major feedback phase loop error.
I'm not sure now what it could have done in there like that with it out of phase.

[timmy]

All it is a 1 ohm coil I checked it and it’s good but really how much oh a feed back voltage could it have made to damage let alone to affect the horizontal drive.