Motorola ts907 low hv

[timmy]

Ok what I’m going to try is a 470k and a 100k together in series and I checked is .560meg that’s better if it works then I’ll go on to check voltages on v6 and v10.

[Yamamaya42]

That's why it is always important to look at the part under test, and not rely on the SAMs alone, cause it can be wrong, or not have updated part info, if the color code on the resistor says 560k and it tests as 800ohms, it clearly bad, but if they stuck an 800 in there for some reason, or a 3.3k like is shown in the (3300) option on the sams, it all depends on what is really in there, but most likely, it really WAS a 560k to start with (green blue yellow silver ) in there, and it drastically went down in value.

[timmy]

Oh I never rely on sams there’s always been mistakes so I do look at what’s in the chassis as I already found that there are parts not listed in the sams and yes I did look at the resistor and I knew it was 560k

[timmy]

Back to the same thing before sound is scratchy distorted and the -45 is jumping all over -39 -41 -30 and so on I can help but think maybe this new flyback is bad oh and no video.

[Yamamaya42]

So, you are saying you have gotten HV back and have a raster again and now back to the point of not able to tune in video?


So it's suggested again that you try a longevity run with video input at test point B, like you had it hooked up there before, ( removing 3rd IF V3), and work on sound and tuning after.

And as it says on the schematic, all voltages and waves are taken with test pattern input, w/o such input, it's understandable that voltages and waveforms will fluctuate as there is nothing to lock them into “normal” ranges.

[timmy]

So the -45v can fluctuate without anything to lock on to so is the horizontal oscillator and agc used with video input at test point b and the IF tubes out ?

[Yamamaya42]

Originally Posted by timmy

So the -45v can fluctuate without anything to lock on to so is the horizontal oscillator and agc used with video input at test point b and the IF tubes out ?

you can leave the other IF tubes in, and remove the 3rd, as it could interfere with the input.

As for AGC, the set has a combo tube, AGC SYNC SEP, , the latter being needed for video lock.

so all that's needed to be pulled is V3, the rest can stay, they will just have nothing to do with no input if they are in the RF/IF stages.

[timmy]

Ok here’s what it looks like and the -45 came back.

[Yamamaya42]

Unfortunately, tuning/IF problems are some of the hardest ones to debug, even with something like a B&K 1077b television analyst or the like, no easy task at all.

You might want to start with a voltage check at the tuner plug, working back through the IF stages 1-2-3. looking at grid, plate & cathode voltages, that may tell you something.

But if tuning / IF is out of alignment, there is little to do other then hope to find someone with a sweep marker generator setup, and who knows how to use it.

[timmy]

What gets me is at the beginning I had clear sound and it slowly went to static distorted sound.

[timmy]

It could also be the tuner it looks like at one time the cover was removed and maybe putting it back maybe cut a wire inside. But still I had sound and if I had sound that would usually mean the tuner is good so if the IF is out I should still have sound.

[Yamamaya42]

sounds almost like an AGC/noise gate issue, advancing those controls CW has no effect?

[timmy]

Neither one makes a difference at all and I thought it was odd that if I touch the antenna to the uhf terminals I get the same thing as if it were on the vhf terminal. I even tried the old tuner tubes. Well the tuner is not immune from drifting resistor’s.

[Yamamaya42]

If the tuner is out, there is very little, if anything that can be done about it, cause there is nobody around who works on them anymore.

They are very hard to work on as you end up doing more harm than good unless you really know what you are doing.

And as stated before, they have these to find out if it really IS the tuner that is faulty.
https://www.ebay.com/itm/16563422078...Bk9SR_DcmuTsYA

[timmy]

Well I have worked on watches very tedious work so if I have to I would attempt it and the unit on eBay how is that hooked up.