Motorola ts907 low hv - Page 42 - Videokarma.org TV - Video

Yamamaya42 · #**616** 10-13-2022, 12:51 PM

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 · #**617** 10-13-2022, 01:10 PM

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 · #**618** 10-13-2022, 01:20 PM

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 · #**619** 10-13-2022, 01:31 PM

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 · #**620** 10-13-2022, 01:45 PM

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.

Yamamaya42 · #**621** 10-13-2022, 01:58 PM

Look at pin 6 on the convergence connector, to which it is also connected to, that is 300v ptp there, who knows what it could have done with that signal inverted.

What would be suggested is that you go over the entire horizontal circuit with a fine tooth comb and re-check every resistor and cap, and if they do not check within 10% replace.

Also, this can check caps for leakage to some degree, https://www.amazon.com/ALMOCN-Transi...s%2C138&sr=8-6

but, out of circuit only

timmy · #**622** 10-13-2022, 02:17 PM

Those 2 connections are separate what I did was reverse the connections 13 didn’t go to ground

Yamamaya42 · #**623** 10-13-2022, 02:29 PM

You said “you had mistakenly reversed 13 and 14 on the flyback”

This tells me that the windnding was putting out a signal 180 degrees out of phase from what it should have been.

The wire that should have been on #13 was on 14 and vice versa, this is what you are saying, right?

Then you should re-check the whole area.

timmy · #**624** 10-13-2022, 02:50 PM

I did check all connections on the flyback the 13-14 on the coil is top and bottom it was reversed within the coil 13 was not on ground it’s just how the wires are oriented the same as reversing a coil polarity to push or pull like a solinoid but it was reversed. I followed that 13 to 2 33k resistors are 35k and a 150k that’s 163k.

Yamamaya42 · #**625** 10-13-2022, 02:56 PM

Quote:

Originally Posted by timmy

I did check all connections on the flyback the 13-14 on the coil is top and bottom it was reversed within the coil 13 was not on ground it’s just how the wires are oriented the same as reversing a coil polarity to push or pull like a solinoid but it was reversed. I followed that 13 to 2 33k resistors are 35k and a 150k that’s 163k.

again, that means it was out of phase, and you should check things.

timmy · #**626** 10-13-2022, 03:01 PM

Well then 150k at 163.7k is just about at max then.

timmy · #**627** 10-14-2022, 10:48 AM

I changed a few resistors still no change but the hot are to have 140v but I’m getting 190v would this still be the case of the drive being off.

Yamamaya42 · #**628** 10-14-2022, 12:44 PM

All I can add is, perhaps you can try to do direct video input again at test point B, and hope to get it to lock on, perhaps the horizontal frequency is way off.

I really do not understand the way things happened here when last week the bar issue was first mentioned.

Snip/paste.
“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.”

“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”

Why was it not mentioned back then that the FBT was swapped from the new back to the old when the bar issue started?
This just lead to mass confusion and had people looking to the wrong places for the reason for the possible cause.

It's really somewhat a mystery to me why it was swapped after it was shown to be OK with the direct video input done previously, the issue of not being able to get a signal in via the tuner is not related to the FBT, more so the front end, (tuner/IF).

Again, I'm not sure what having that winding hooked up reversed did, but it could not have been very good for the set.

Please be more straightforward about such things to avoid future confusion, had you said that the bars started after you put the old FBT back in, things would have been much more clear.

Remember how I was immediately suspect of the reduced screen width? Something was telling me there was something wrong there.

timmy · #**629** 10-14-2022, 03:20 PM

Ok so I put the old flyback back in and the voltage at the hot is now 130v other voltages are looking better on v12 v10 and maybe once the anode is on the tube it will show higher hv now with the reg cap off and warmed up I’m getting 24 kv so once the chassis is put back in hopefully the voltages level out I can’t expect to get perfect voltages with the Chassis on the bench. I would have expected the hv to rise to at least 30kv with the reg cap off.then again the crt acts like a capacitor so it will probably rise to 30kv.

timmy · #**630** 10-15-2022, 09:09 AM

So back on track hv very good after 15 minute warm up voltages are still not right
275=266 190=187 145=143 not bad but after it running additional 10 minutes the voltage drops off
275=255 190=170 145=130 and no matter where the voltages are still no video. Using the new dvm if I’m reading it right on 10 amp or the other amp settings it’s showing either 0.055 or 055 so I’m not sure if this means 550ma.