Motorola ts907 low hv

[timmy]

So if the tuner subber works and I get video and sound then it is the tuner so I checked that it has 130v and 145v and that’s good There is a 4700 ohm resistor after the 130v and 1200 ohm after the 145v so if I have to get into the tuner those 2 resistors are what I’m going for first.

[zeno]

Originally Posted by Yamamaya42

R93 had changed value to 800 ohms, from 560k, believe it or not

Two other common examples of resistors going down. All IIRC numbers.
GE 18" S-1 compactron POS sets had an 8.2K 2W that went way down.

Sylvania 19" hybrids two 56K 2W that went between the high B+ & the
24 V for the color ckts. They went down & smoked lots of stuff in
the color.
Other than those I cant remember any other fails with ohms going DOWN.
On Motos I do remember big brown resistors in the demod opening
& giving missing colors.

73 Zeno
LFOD !

[Electronic M]

Originally Posted by zeno

Two other common examples of resistors going down. All IIRC numbers.
GE 18" S-1 compactron POS sets had an 8.2K 2W that went way down.

Sylvania 19" hybrids two 56K 2W that went between the high B+ & the
24 V for the color ckts. They went down & smoked lots of stuff in
the color.
Other than those I cant remember any other fails with ohms going DOWN.
On Motos I do remember big brown resistors in the demod opening
& giving missing colors.

73 Zeno
LFOD !

Soinds like the D-12 Sylvania chassis they put that chassis in consoles too.

[timmy]

Got the tuner subber works good but it looks like the problem is in the IF strip having the subber in and increasing the gain I can see an image but all distorted along with sound so now back to the drawing board focusing on the strip.what causes a ceramic cap to be shiny and greasey looking while there are several other disc caps next to the one that’s shiny yet only that one and not the others next to it.

[Yamamaya42]

Originally Posted by timmy

Got the tuner subber works good but it looks like the problem is in the IF strip having the subber in and increasing the gain I can see an image but all distorted along with sound so now back to the drawing board focusing on the strip.what causes a ceramic cap to be shiny and greasey looking while there are several other disc caps next to the one that’s shiny yet only that one and not the others next to it.

plz post pic of the screen image.

[timmy]

Same as the other image I posted only alittle more detail with the gain all the way up and I already pulled the chassis

[Yamamaya42]

Same as the " Godzilla " one last week? :O

[timmy]

This one but the gain up on the subber things are more able to make out

[timmy]

I know without a scope to get past each IF tube to rule out is going to be a tough nut to crack. I originally had sound but the one day it just fizzled out if the volume is up I still have sound but scratchy static so since the sound is off the 3rd IF it can still be anywhere from 1-3 IF tubes.

[Yamamaya42]

Unfortunately, this means that the IF is most likely badly out of alignment, most likely been tweaked.
Where as something like this MIGHT be caused by a bad component, if it was, it would more often than not be a faulty resistor than a bad capacitor, or even less likely a coil, cause as stated before, disc capacitors seldom ever go bad unless subjected to physical or electrical extremes, and since you have gone through and tested the resistors already, options are limited.

You may try to check all voltages on the pins of the IF tubes to see if they match what is listed in the schematic and hope to find something drastically wrong, but failing that there is not much else to do, other than hope to find someone with an alignment test setup, to debug/align the faulty stages, or bypass the RF/IF stage completely and go direct A/V input.

[timmy]

I don’t think it was tweaked because I had good sound and now it’s all static but can here the sound it self and I had a picture flickering in and out with the subber gain at max so I’ll have to go over resistors again and clip if I have to.

[timmy]

Is it possible that there is a problem in the sound detector v7 being the sound is off v3 3rd IF if there is a problem in the detector would it affect both sound and video seeing as both sound and video comes off the 3rd IF. Just a shot in the dark.

[Yamamaya42]

they use Intercarrier for sound, it's folded into the video.
C43 is the bypass cap for the sound det, sort of works like an FM radio, what is most likely going on is that by the time it gets from the tuner to the 3rd IF, the signal is so distorted, there is nothing for the sound det to work with.

[timmy]

The loss of sound has got to be why I can’t get video because I had sound initially it’s got to be the same problem unless it’s a really hard coincidence

[timmy]

What about the 1n60 if that is leaking I know it would take out the video but would it affect sound