Motorola ts907 low hv

[Yamamaya42]

You have 2 places to try to inject video as EM suggested, it may help you a lot to try it.
http://suzaku.live-evil.org/injection-points.jpg

But as shown on the SAMS, it expects 5v pk-pk at that amp, and composite is only just about 1v, but you should see something.

There is also that 13v potential to deal with, so be sure to feed through an appropriate film cap .01 (guess).

I have done this myself many times with good results.

[timmy]

I do get alittle snow and some lines on top of the screen but to inject a signal would be kind of Impossible hectic access these Motorolas have test points on top of the chassis but the sams don’t show what they are for testing what.

[Yamamaya42]

Originally Posted by timmy

I do get alittle snow and some lines on top of the screen but to inject a signal would be kind of Impossible hectic access these Motorolas have test points on top of the chassis but the sams don’t show what they are for testing what.

I literally soldered on a lead of a cap to pin 7 of the first video amp on my RCA CTC-16XL when I was working on it to feed in video.

[Electronic M]

When a point is hard to reach with the chassis installed I pull the chassis enough to reach it, hook an alligator clip lead up to it to bring it out to an easy to reach point and use that.

If you happen to have a working TV test pattern generator with variable output most of those were designed to give 5V or more output to give a nice contrasty output.

[Yamamaya42]

Test point B is quite easy to reach from the top of the chassis, and clearly pointed out in the SAMS, you can clip there for video input.

[timmy]

Where on the schematic is test point B on top of chassis would that be to pin 7 of 6aw8

[Yamamaya42]

Originally Posted by timmy

Where on the schematic is test point B on top of chassis would that be to pin 7 of 6aw8

pint b is here

http://suzaku.live-evil.org/poin-b.jpg

its between l10 and l11

http://suzaku.live-evil.org/injection-points.jpg

i have be using this, which i assume is correct?

https://www.earlytelevision.org/pdf/...sams_739-3.pdf

[timmy]

Oh obviously I’m missing that page that shows point B. Yes you have the correct schematic.

[timmy]

Ok so on channel 4 I can almost tune in a picture but can’t make anything out of it and it looks like the horizontal hold needs to be adjusted i tried but won’t clear up so I don’t know if the sync section can keep a picture from displaying along with the h hold not being able to adjust out. I ran the slug all the way in to all the way out.it’s clearly trying to tune in since I got the tuner working properly but just won’t tune in and sometimes on 3 the sound fades like it’s out of tune so the video is getting to where it should. Just when I think the pic is going tune in it don’t it’s that close.

[Yamamaya42]

This of course points right back to the low HV area problem.
For some reason, the circuit is not able to synchronize to the incoming video input, this could be for many reasons.

SYNC SEP, SYNC AMP, HORZ AFC, HORZ OSC , & all associated circuits are suspect.


I hate to keep repeating it, but it's the way it is, w/o an oscilloscope to check that you are getting the right signals at the right points in the circuits, you are making this exponentially harder for yourself than it needs to be.

[timmy]

Well yes I know a scope would be a big help and yes it’s frustrating seeking problems without it but as for the hv as I mentioned in an earlier post the problem was a bad ho tube and I even checked ohms on the horizontal hold coil which checked out perfect. And those circuits you mention all new caps and endless resistors checked perfect. This set is beginning to give me a headache lol. Even tubes keep checking them. Those metal shield’s in the IF section is it important to replace 3 solder connections to ground even though there are screw’s holding the shield in place to ground.

[timmy]

So is it safe to say that if you have sound then the video is there as well. I know audio goes one way and video goes in another direction I’m trying to rule out the tuner the slugs do move, I since got those gears to move freely.

[Electronic M]

Video and sound typically stay combined until the output of the video detector. If you have sound the tuner and IF are not dead...God only knows if fine tuning, IF and audio alignment are correct, or if your video amplifier works at all.

Without a scope or a means of/will to do signal injection such as the procedure I discussed earlier you're basically flying blind without instruments.

There comes a time where the value of the time you waste trying to make do with insufficient test gear is worth so many times the cost of a working used $50 1970s or newer scope, B&K analyst, etc that NOT buying one is costing you much more than buying one.

[nasadowsk]

Watch “that auction site”. You can find even a recent Tektronix for cheap, and that’s all the scope you need to get up and running in scope land. When you see what a scope can do for you, you wonder why you didn’t get one sooner….

[timmy]

Well I have been in the video amp but I didn’t check the video output maybe something there would cause this video issue. How about the blanking circuit ?