silvertone roundie - Videokarma.org TV - Video

timmy · #1 10-23-2012, 05:34 PM

hey all i have not got started on this silvertone ctc12 clone yet to find out why the hv jumps up and down with scene changes and the cathode current jumps as well. i will be checking the 390k resistor at the blanker tube to ground since it was said to do this if the resistor is out or the ground trace is bad. so with all the talk about the low hv on that ctc5 does this sound like anything to anyone? 24kv at the crt but it jumps around with scene changes as low as 19kv and with that the cathode current to. this set was not right from the beginning with the hv. all the caps in the horiz section was changed and more. i changed probably more caps then i should have. shunt tube is new , rect tube, resistors in the hv adjust string checked good, resistor at the 6dq5 was changed. the crt bias has to be all the way counter because if i raise it just a touch the whole screen turns to blurr and the hv takes a huge dive, any ideas befor i go ahead and look at something that will get me nowhere,lol,lol....

miniman82 · #2 10-23-2012, 09:26 PM

Sounds like a bad brightness control (or that bias pot you mentioned) to me, the blooming is caused by excessive current draw so if the screen brightness is all over the map that's where I'd start.

ctc17 · #3 10-24-2012, 09:22 AM

What's the model number??

timmy · #4 10-24-2012, 10:57 AM

i think its stamped 3129 or 28 i think its 1963 with the ctc12 clone. its the one on this page on the left.

DaveWM · #5 10-24-2012, 11:16 AM

If it's a CTC-12 clone then you will not have the same problem with the blanker tube bias effecting the HV production, that did not happen until the CTC-15. It was a backup to runaway HV if the shunt tube failed.

If it has a 1.5 meg resistor from the control grid of the HOT to the term TT on the chroma board, then you have the blanker tube bias issue.

timmy · #6 10-24-2012, 11:30 AM

Quote:

Originally Posted by DaveWM

If it's a CTC-12 clone then you will not have the same problem with the blanker tube bias effecting the HV production, that did not happen until the CTC-15. It was a backup to runaway HV if the shunt tube failed.

If it has a 1.5 meg resistor from the control grid of the HOT to the term TT on the chroma board, then you have the blanker tube bias issue.

the 12 schematic shows the same 390k resistor off pin 2 of the blanker tube just as the 15 and 16.

DaveWM · #7 10-24-2012, 12:16 PM

I give up

ctc17 · #8 10-24-2012, 01:36 PM

Ok first forget the clone crap, thats something the super elite do so they have spare parts.

Whats the model number, its going to be something like 528.555555 and it will be on the back.

It may not be a clone at all, it may be a spinoff...how about that?

We need to start with the right model number and schematic and stop telling the tv what it is.

timmy · #9 10-24-2012, 03:27 PM

Quote:

Originally Posted by ctc17

Ok first forget the clone crap, thats something the super elite do so they have spare parts.

Whats the model number, its going to be something like 528.555555 and it will be on the back.

It may not be a clone at all, it may be a spinoff...how about that?

We need to start with the right model number and schematic and stop telling the tv what it is.

ok the chassis dont have a number on it but could use this number from the sams which is this chassis, 528.61110 hope this helps. and as far as this bias problem i had read a thread here on karma about this resistor from pin 2 of the blanker tube to ground and yes it was said that it started with the 15 chassis but no one knew if possibly it went for the 12 unless the sams was looked at for the 12 and it shows just that resistor in the very spot from the 12 to 16 chassis and there is no 1.5 meg resistor that i found on the 12.

ctc17 · #10 10-24-2012, 03:43 PM

Look very close at the boards, most of the time sears has a little metal tag soldered into the board facing back with the number stamped into it. It looks like a little flat capacitor or something.

timmy · #11 10-24-2012, 04:05 PM

Quote:

Originally Posted by ctc17

Look very close at the boards, most of the time sears has a little metal tag soldered into the board facing back with the number stamped into it. It looks like a little flat capacitor or something.

ok ill have to get the chassis out and find this number. i was just fishing for maybe something i could have looked for as a simple fix without pulling the chassis.

ctc17 · #12 10-24-2012, 04:18 PM

You dont have to pull the chassis out. Its sticking up out pf the board facing back at you

Im working on getting our dearest timmy to get me a verified model number so I can get the correct sams and post a photo of the area of interest.
I went through a bit of trouble to compile a fairly complete set of sams and its ridiculous to be guessing what resistors it may have and what it may be a clone of. It takes me fairly little effort to grab the correct schematic and scan it.
We already left poor davewm in the oven to long on this one getting sidetracked on what might be

timmy · #13 10-25-2012, 02:23 PM

ok dan heres the chassis number 528. 61115 there was a paper tag on the back. i also checked the 390k resistor from the grid of the blanker tube to ground and its 248k its down from what it should be, dont know if this is a factor.

ctc17 · #14 10-25-2012, 04:03 PM

Very good, do you have a copy of 655-2?

timmy · #15 10-25-2012, 04:15 PM

Quote:

Originally Posted by ctc17

Very good, do you have a copy of 655-2?

yes that is the very folder i have 655-2