Motorola ts907 low hv - Page 82 - Videokarma.org TV - Video

timmy · #**1216** 12-09-2022, 08:26 AM

So really it’s just a 200 ohm pot nothing special just a variable resistor and that part number you posted is the same as in sams except the sams has a 1 on the end. I didn’t turn it but I get zero

Yamamaya42 · #**1217** 12-09-2022, 08:43 AM

Quote:

Originally Posted by timmy

So really it’s just a 200 ohm pot nothing special just a variable resistor and that part number you posted is the same as in sams except the sams has a 1 on the end. I didn’t turn it but I get zero

it's OK, all as it should be!

Take a look at L6 as a whole, and the alignment procedure, L6 has 2 parts in it, the 3rd if transformer, (A4) and the sound trap, (A1), both having tuning cores, the sound trap has a 2nd adjustment which is R22.

A1 & R22 interact with each other when adjusted to suppress the sound after takeoff so it does not get to the video amp.

timmy · #**1218** 12-09-2022, 09:04 AM

Either way shouldn’t this trap have some sort of resistance reading?

Yamamaya42 · #**1219** 12-09-2022, 09:25 AM

Quote:

Originally Posted by timmy

Either way shouldn’t this trap have some sort of resistance reading?

It can be set anywhere from 0 to 200 ohms, depending on what is needed to get correct operation of the 41.25mhz trap, as set in step 2 & 4 of the alignment.

timmy · #**1220** 12-09-2022, 12:00 PM

Well I took the trap out it’s completely open tried alcohol no good but I put a pot together and it’s no where near 200 ohms just a test but this is the result it came alive still have more to do but this trap caused a lot of headaches for me a scope would have picked this up right away.

timmy · #**1221** 12-09-2022, 12:13 PM

Why would the mtc22L1 have a wiper but the 22L4 don’t and matches what’s in the set already.

Yamamaya42 · #**1222** 12-09-2022, 12:56 PM

This is getting confusing...

You said you got a reading of “zero” which I interpreted zero ohms or dead short, or zeroed out as in closed to the extreme, but did you really mean it was open or a reading of infinite resistance?
If so, you really did not get that across well, and the trim pot is indeed bad, and the one listed is a replacement as shown on the SAMS.

timmy · #**1223** 12-09-2022, 01:57 PM

Quote:

Originally Posted by Yamamaya42

This is getting confusing...

You said you got a reading of “zero” which I interpreted zero ohms or dead short, or zeroed out as in closed to the extreme, but did you really mean it was open or a reading of infinite resistance?
If so, you really did not get that across well, and the trim pot is indeed bad, and the one listed is a replacement as shown on the SAMS.

The trap shown on sams is 22L1 but the one you found looks like the right one without the wiper. and yes I found that the trap was open from 57 years of vibration wore down the connections on the porcelain base so I took the cap off and put a bead of solder on each one and now it’s 200 ohms and it’s good now I put it back in. What is color bands across the screen when the color is turned up ?

Yamamaya42 · #**1224** 12-09-2022, 02:34 PM

Quote:

Originally Posted by timmy

The trap shown on sams is 22L1 but the one you found looks like the right one without the wiper. and yes I found that the trap was open from 57 years of vibration wore down the connections on the porcelain base so I took the cap off and put a bead of solder on each one and now it’s 200 ohms and it’s good now I put it back in. What is color bands across the screen when the color is turned up ?

PIC?

The correct setting for R22 is someplace between 0 & 200 ohms, but setting it has to be done in the alignment setup with a RF generator and scope, trying to do it visually most likely wont work very well.

timmy · #**1225** 12-09-2022, 02:42 PM

Color bars

Yamamaya42 · #**1226** 12-09-2022, 02:55 PM

herringbone patterns again, An over all indication that the response curve of the IF is not correct, added that the sound trap may also be not right and letting audio into the video amp.

timmy · #**1227** 12-09-2022, 04:48 PM

How is it that you can have a clear good b&w picture and yet it won’t accept color how does these frequency’s work for color.

dtvmcdonald · #**1228** 12-09-2022, 08:14 PM

You need to read on how color TV works, again. In any case, if you have the color control turned way up and the oscillator is working you should get color
at some position of the fine tuning, maybe one with a really bad B&W image,
even if the IF is badly misaligned. Last spring I worked on the CTC5 at the ETF.
I got color, in fact good color, but the B&W picture looked even worse than
yours. I didn't have time to do an alignment.

If you don't get any color, the first thing is to bring the antenna of a regular
short wave radio in CW mode up to the color oscillator and see if there is
a whopping signal at 3.58 MHz.

Problems with the pulses generated by the horizontal output transformer
can cause no color to get through the color amplifiers. The feedback in the color area is so complicated that no color is a nightmare even with a scope. Wrong color is a lot easier.

Yamamaya42 · #**1229** 12-09-2022, 09:18 PM

This is prof positive that the color circuits of your TV is working.

http://videokarma.org/attachment.php...9&d=1669302177

color with direct input.

I had the very same problem a few years back with my CTC-16XL.
After I spent a VERY long time getting the color circuits working again after some putz messed it all up, and I had to use direct input to do so, I still could not get stable color via the tuner cause the IF was all borked because it was messed with was very obvious as the shield for it was missing.

A telltale sign of messed up IF is getting good BW but crappy or no color, why it does this is complicated, but it has to do with how they took the normal BW video standard and crammed color info into it and still had it compatible with older non color sets.

And most of the time there is no fix other than alignment,because otherwise the color info will be corrupted by the time it gets to the video amp, even if you get a semi good BW video.

Even on my CTC-16XL I was not able to clear up the IF as good as it should be, it's like 85-90% and shows red smear, and thus I have installed bypass signal relays in the A/V lines and can change from tuner to direct input at a flip of a switch.

perhaps someday If i ever get a sweep marker generator, i may attempt to bring it up to par.
but for now, it's really good with direct, and fair with tuner.

timmy · #**1230** 12-10-2022, 05:28 AM

Well at this point all I could do is blow a lot of time trying to adjust things here and if I’m at all lucky maybe I can pull this off. Even if I had the proper things to do an alignment I still don’t know how to perform it. Since finding this trap open and restoring it the b+ voltages are finally normal the 256v is now 276v where it should be. All the time trying to make adjustments with blinders on don’t mean I’ll get it right but I’ll try.