1980 RCA Colortrak 25" troubleshooting help

[groovy]

Originally Posted by compucat

That is a beautiful set. I can see why you want to keep it going no matter what. That cabinet style is stunning. So much better than the soulless black slabs that most flat pane sets are. I am not familliar with that chassis but if it is modular, I would suggest checking all pin and cable connections. Also make sure the CRT socket is making proper contact with the tube pins. It might just need to be cleaned out inside and have all the interconnecting cables reseated.

compucat, thanks for the reply and suggestions! It is a beautiful cabinet. I think it is the nicest one RCA ever produced - much nicer to look at in a room than a flat black panel as you stated!

The other day I did take the yoke plug off the CRT and cleaned the contacts with deoxit. I also did check cable connections. Unfortunately it didn't make an improvement.

[zeno]

Start by tapping around lightly.
Check the CRT socket for cold joints.
Bright white w/retrace almost always means:
1) loss of 200v supply off flyback
2) bad drive from luma causing the 3 outputs to go very low.
3) too much G-2
4) on SOME sets H-K short on CRT ! Instead of going the color
of the shorted gun it will go white !
Keep in mind low cathode gives brite pix & hi gives black.

Second thing is the tuner PKG. Some used one big tuner others
used used two PKG's plugged together. Where wire bundles
come in or plug in resolder were they come in. Caused all kinds
of intermittents but probably NOT yours.

OH yah, how about some nudies of the chassis ?

73 Zeno

[groovy]

Originally Posted by zeno

Start by tapping around lightly.
Check the CRT socket for cold joints.
Bright white w/retrace almost always means:
1) loss of 200v supply off flyback
2) bad drive from luma causing the 3 outputs to go very low.
3) too much G-2
4) on SOME sets H-K short on CRT ! Instead of going the color
of the shorted gun it will go white !
Keep in mind low cathode gives brite pix & hi gives black.

Second thing is the tuner PKG. Some used one big tuner others
used used two PKG's plugged together. Where wire bundles
come in or plug in resolder were they come in. Caused all kinds
of intermittents but probably NOT yours.

OH yah, how about some nudies of the chassis ?

73 Zeno

Zeno,
Thanks for the response and direction. Loss of 200v supply from flyback seems to be my first point of investigation. VK Member RCA2000 suggested in an above post that the choke coils are suspect and after studying the schematic, there are four in the 200v supply from the flyback to the CRT kine socket. These are all very suspect now in my opinion. I have sourced replacements from Mouser and at $1.25 each - they will all get replaced. If this doesn't do the trick, I will move on to the Luminance circuit. There is an IC chip (luminance processor) and a buffer transistor that would be the next suspect. I will post pics of the chassis once I get these new coils and open it back up.
Many thanks again for the insight!