Rca ctc-5

[DaveWM]

normally when I am replacing parts on old wafer style tube sockets, I just clip the lead and pig tail, this is to prevent breaking a tube socket pin connector and ruining my day.

In this case it was just the 270 ohm resistor and I could see it was not really wrapped around the hole, so I got out the solder wick and safely removed the resistor. Replaced the resistor all looked good, the only other connection to the tube socket was the wire that went to the blanker tube socket, but I did not disturb that.

I always confirm my work so if its a pig tail I make sure I have good continuity across the pig tail connection (if the wire is not clean its easy to have a good looking connection but no actual contact INSIDE the pig tail.

in this case I did not have to worry about that as I could see I had good flow and had filled the hole in the tab with solder. I did check to make sure the wire that goes to the blanker tube cathode was still good and surprise, it was open. a closer look and I could see the wire had broken right at the pin that I had just soldered to. it was partially corroded and I guess the minor movement done in the install of the resistor must have broken it.

I had to fish the wire out and strip it to get a good clean piece, lucky there was enough slack (just). solder wick out the connection again and redo thru the hole and wrap, solder back. Needless to say I was very careful as the socket tabs break easy.

when done I confirmed that I had continuity back from the pin thru the wire to the other tube socket, AND the 270 ohm resistor was still 270 and connected.

Watch out for those very fragile hookup wires used, in this case I think it was 26 gauge solid so not much to break it.

[DaveWM]

after fighting poor greens I decided to try the vectorscope again. this time I clipped on the other side of the grid coupling caps for RGB on the CRT. Much better, did not effect the CRT display at all.

While there were color bars, the blue and reds were fine but the magenta was weak as was the green.

looking at the scope you could see the fingers but they were much more of an elipse that an a circle.

My interpretation of this is the phase of the CW from the osc was not correct to one of the demodulators, and the transformer that changes the phase needed to be adjusted. Since green is derived from the X and Y demodulators, then a defect there would really mess up green.

What I like about the vectorscope is the instant visual response (not just that its changing but that its changing in the right direction.

as it turned out about 1/4 turn of that phase adj transformer was able to open up the elipse and give a nice circle pattern, when I looked up at the CRT it now had a very nice color pattern.

This is the second time the vectorscope came to the rescue for me, I highly recommend one. Besides they also have nice dot and cross hatch settings.

funny thing is how good you can get flesh tones even with green so useless, I guess its just the flesh tone does not need much green unless your looking as Spock.

[DaveWM]

color looks great, but it was a bit weaker than before (which makes sense as the elipse was larger than the circle) a tweek of the ACC (which controls the chroma band pass amp gain based on burst amplitude) fixed that.

I still plan to make a custom top for the fly cage, it will have a plenum with a built in filter to help keep the fly temps low. Even with the low current thru the fly (about 175ma) it gets hotter than I like after extended viewing (hit about 165f after about 1 hr).