Motorola ts907 low hv

[timmy]

Originally Posted by Yamamaya42

It's not recommended to do anything with the caps / resistors in the tuner, because to disturb them can cause more harm than good, even if they are out of tol.

What could be done is removal of the drum to allow better cleaning, but this is not easy to do as the spring clips holding it in on each end are a pain to get in and out, and very close attention to detail to all the parts on both ends of the shafts must be taken so that they go back in place.
But, once the drum is out, you have easy access to the spring contacts inside for cleaning and tightening if needed.

Ok got the tuner cleaned and checked resistors while in there a 220k was 260k and 4.7k was 5.6k the rest were good so I left them alone all I did was clean the spring contacts and the turret contacts and the spring contacts looked really used and there must have been old tuner spray that turned into sticky like molasses but got it cleaned. And yes clips and springs was fun but was not a problem for me it went back together just fine.

[timmy]

Ok tuner cleaned and ruled out no more flickering. So now even though it’s said not to take things to be right in sams like the voltages the Motorola schematic shows voltages higher then sams so the next thing is I really need to find out why the voltages are so low in this set even after 15 minute warm up.
275v=256v
190v=177v
145v=140v
640v=539v
770v=750v
Motorola shows much higher, these voltages are just to low something is not right. Pin 8 of v6 is supposed to be 230v but it’s 110v so if the main power supply voltages are low so is everything else. I had already checked out the power transformer and found it to be fine and 15 minutes is long enough for the thermistor to heat up and I had checked that as well IIRC it was 1 or 2 ohms. And all this is checked with 121v at the outlet.

[Yamamaya42]

Again, no 2 sets are alike, so you should never take the voltages listed in the SAMs as an absolute, variances of 5-10% is normal.

[old_tv_nut]

Originally Posted by timmy

Ok tuner cleaned and ruled out no more flickering. So now even though it’s said not to take things to be right in sams like the voltages the Motorola schematic shows voltages higher then sams so the next thing is I really need to find out why the voltages are so low in this set even after 15 minute warm up.
275v=256v
190v=177v
145v=140v
640v=539v
770v=750v
Motorola shows much higher, these voltages are just to low something is not right. Pin 8 of v6 is supposed to be 230v but it’s 110v so if the main power supply voltages are low so is everything else. I had already checked out the power transformer and found it to be fine and 15 minutes is long enough for the thermistor to heat up and I had checked that as well IIRC it was 1 or 2 ohms. And all this is checked with 121v at the outlet.

Try to differentiate between voltages that are all off by 20 percent and those that are off much more.
If all are off by 20 percent then none are pointing you to a particular trouble. The ones that are off by a much greater percent are telling you where to concentrate your trouble shooting. Pick one at a time to work on, and eventually you will fix one and then another.

[timmy]

This is as much video I have got so far from the sets own tuner but is there another area I could look into like maybe the blanking amp judge by what the image looks like since I turned the IF coils one at a time and kept count in or out but if I turn them I start to lose the video so I left them alone. I’m just trying to figure out if another circuit besides the agc could make this image like this. No change in turning the agc little difference when turning the noise gate.

[timmy]

If agc can distort and mess up video shouldn’t it kill audio as well.

[Yamamaya42]

The posted pics are still a very strong sign of a IF alignment problem. The picture almost looks negative, much worse than when fed in at the 2nd IF or test point A.

As many will say, you can NOT adjust the IF visually, simply tweaking a coil a bit to see if it improves what you see on the screen will get you no results, as they interact with each other, the entire process must be followed with a rf frequency generator or sweep marker generator anything else will just make is worse, as anyone else can tell you.

[timmy]

Yes the video looks like a negative but the pic I posted back a few pages was done with the subber on pin 2 of v2 but since changing the 22ohm resistors in v1 and v2 I am not able to get that back again not sure why

[timmy]

It was said in a previous post that if the trap at the antenna input was bad it would be impossible to tune anything in so with that said if the trap were good then if it’s turned in either direction it should change what’s on screen already to at least some degree this one does nothing at all and yes I marked exactly where it was before touching it. Is there a way to tell if it’s bad sams says it’s a 15k pot which it is a pot but it only uses 2 connections no center wiper so I guess it varies the 15k itself from under the adjustment knob.

[Username1]

That almost looks like a detector circuit problem.......

Does it get sound? noise that changes with
channel selection?

I think maybe you should contact a Priest and get
an Exorcism for this tv......


.

[timmy]

Originally Posted by Username1

That almost looks like a detector circuit problem.......

Does it get sound? noise that changes with
channel selection?

I think maybe you should contact a Priest and get
an Exorcism for this tv......


.

It does get sound. Detector circuit ? ? There is snow and noise on screen. Are you referring to the video detect area of the detect diode ? I put video in test point b and I noticed there is a slight waving in the video where else could this ac be getting in since the power supply caps are new.

[Username1]

The 3 pictures you posted above look to me like the delay line is open, and you are
just getting the color portion of the picture to the screen. Only in this instance
it looks like there is no color.....

Does the color control, tint, or contrast control have any effect on the picture?
If any what does each control do? Be specific to each, and the effect.
be clear in your description.

Is the detector diode in there correctly, not backwards. Are each coil close
to the correct resistance? Voltages on the Video Amp & Output ok?

Is the sound crisp & clear, full tone no noise mixed in etc.....
Full clear volume?


.

.

[timmy]

Originally Posted by Username1

The 3 pictures you posted above look to me like the delay line is open, and you are
just getting the color portion of the picture to the screen. Only in this instance
it looks like there is no color.....

Does the color control, tint, or contrast control have any effect on the picture?
If any what does each control do? Be specific to each, and the effect.
be clear in your description.

Is the detector diode in there correctly, not backwards. Are each coil close
to the correct resistance? Voltages on the Video Amp & Output ok?

Is the sound crisp & clear, full tone no noise mixed in etc.....
Full clear volume?


.

.

So since pulling the tuner and cleaning it I have snow noise on Screen and sound and there is snow noise on other channels strongest on channel 3 and sound is strong and clear no noise in with sound. Detector diode is in correctly and the diode test indicates it’s good at a reading of 283 but don’t know if it may be leaking.it’s said anything under 3 in a germanium diode is good. It has a 1N60 but if I have to change it all I have is a 1n34 don’t know if it’s compatible. I injected video to make sure the amp and output is still good and it is good but there is no color because I turned the drives down along with the master g1. And I had already checked the IF coils and they are .2 or.3 . When the color drives are up the video I’m getting now there is not a lot of contrast but with video injected the controls work. If the color drives are up the other controls seem to put kind of noise on the screen so I turned them down since nothing is setup no purity nothing. Back when I posted the pic and you said I can see some red in there I had got that from pin 2 of v2 with the subber but since I changed the 2 - 22 ohm resistors in v1 and v2 I can’t get that same result the resistors were 26ohm and 28ohm so they needed to go. Well ok there is a problem I tried to get some color but to my surprise the hue and intensity is not working but the contrast has an affect so that works. It does look like I lost the color no matter how I turn the color drives.ok another update all the color controls do work I had the color killer turned down. I checked with injected video color is there.

[timmy]

This is the latest don’t know why it flips.

Video amp
9-172
7- 13
8- 116
6- 14
Video output
7- 250
6- 153
2- 11
1- 11

[old_coot88]

Is it possible the video detector diode has gotten reversed? (I haven't read thru this whole tome, so this might have already been asked.)