Riddled TV Repair Forum

badboy · Joined: 08 Dec 2007 Posts: 6 Location: Westland,michigan

NO GREEN
RCA 19 inch Model#F20632SE
CHASSIS CTC186A/A
Being a repairman for the music industry, mostly tube amp restoration, modification and repair, I know my way around a PCB. But am not so hip on TV'S. If only I had a schematic... But While playing PS2 with my son, all of a sudden with no noise at all, the picture looked redish purple! I adjusted the tint, but no green! The football fields grass is black! After much testing, it IS the TV. A cap designated C4107k on the PCB looks smokey on it but I cant read the value. C4107k it, says it is on the chassis board, a schematic service manual or diagram would be very helpful, any help would be very greatly appreciated!
thank you!

Google

kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

According to my notes,
C4107 = 100uF/250V

badboy · Joined: 08 Dec 2007 Posts: 6 Location: Westland,michigan

Great, Thanks. I know how to discharge the CRT, but how do you get the PCB out off the chassis after removing the screws on the bottom of the chassis. The inside of this TV looks ALMOST IDENTICAL to the TV in the 2nd picture of "how to discharge a CRT without killing yourself"article. The burnt looking cap is the larger cap just in front of the transformer to the left of the red alligator clip on the heat sink, if you enlarge the second picture of the discharge the CRT article you can see it perfectly. Does it seem reasonable that this cap is the culprit? If I can just get the PCB out I can replace it and see. Please help the newbie out? We were all once a newbie right? Thank you so very much for your patience and input!
badboy

kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

on just about every RCA I have worked on, there are:
-two screws on the bottom side
-1 screw with a plastic washer-thingy near the button side of the board
-Sometimes there is a nut around the tuner's F-connector
-If it has a line-in, there is a little plastic piece next to the RCA jacks. You can take an awl and poke the center out, and then remove the plastic piece.
-check for any others, I may have missed something

then pull the board out of the plastic slider toward the button side.

badboy · Joined: 08 Dec 2007 Posts: 6 Location: Westland,michigan

Is it absolutly necessary to discharge the CRT to do this? (is this a dumb question?) I got the screws out, the push pin by the rca's and the clip thing and it will slide out now,unplug the connectors on the board to slide PCB out? I guess discharge should be first like on a tube amp huh?

thanx- dumb badboy

Google

kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

Look at it this way: discharging the CRT correctly won't kill you. It takes less than a minute.

badboy · Joined: 08 Dec 2007 Posts: 6 Location: Westland,michigan

kuhurdler- I got the chassis out and all the caps with the smoke on them checked out fine so I pulled them out and checked them again and all but a 10uf @200v I pulled and it tested .oo1uf were good. By the way the cap you said was a 100uf@200v, you were right on! When I was touching stuff gently to see if anything was loose a part between the degauss plug and the blue relay just fell apart. It looks like some sort of protection device made out of ?Zinc? with 2 leads on it and stamped 100 01A above 178D on it and RT4012K on the PCB above the cross hatches on the PCB. I am still lookin around for a cap and I soldered the leads back on the part but I dont know if I should fire it up with it like that. Do you know what that part is so I can replace it? I hate working on "new to me" stuff without a schematic. Any more help would be GREATLY appreciated from any one! Thanks so much!

kuhurdler · Joined: 28 Dec 2006 Posts: 2582 Location: Overland Park, KS

thats the degauss posistor. Some people call it a thermistor.
It's in the next to last picture in How to Clean a filthy... article
I think it's safe to solder the legs back on. It would be better to replace it though. Thats my second biggest complaint with RCA TVs. I'd guess it breaks in over 75% of RCA TVs of that era that I've worked on.

What are you using to test these caps? Is it an ESR meter? or are you measuring the capacitance?

badboy · Joined: 08 Dec 2007 Posts: 6 Location: Westland,michigan

I used a capacitance meter, tested in and out of circuit. the caps were not blown, the smoke? wiped right off ,they werent burnt and all but a 10uf @200v tested ok. replaced the 10uf, soldererd the legs back on the degauss possitor or thermistor and still no green. What part of the circuit is that in or what general area , or what usually makes a no green issue? the rest of the TV works prefect. Its only 8 yrs old and not used much in excellent condiion ! This is the first thing I have not been able to fix and Its driving me crazy! if only I had a schematic! rockinbadboy@sbcglobal.net

silv · Joined: 07 Jun 2007 Posts: 57

You should look for the green driver transistor on the crt board and test. there should be 3 of them red,green and bue drivers and they should measure same volts on same pins, also check the 3 resistors they should be around 15k all of them not shure about that modle# but they sould be same ohms.and if the all video components test good, then your fault could be the t-4 chip (jungle Ic)