RCA CTC-36 Woes

[zenithfan1]

It's not all that rare or valuable, part it out and smash the rest in the dumpster. Your other one is great but when these get this beat up, they're hardly worth the effort to bring back. Unless, you're into that sort of thing... Nice work on the good one BTW

[Kamakiri]

The cabinet's about half as ugly, too. Good picture tube though......

[Kamakiri]

So....back on the CTC-36.....the good one

Did some work on it, and replaced 4 caps in the vertical. One, much to my surprise, had a loose solder joint.

The set looks great, but I'm having one problem that I just can't shake. I just can't get the red horizontal convergence correct....it's off to the right on the crosshatch. I won't say that it's off linearly, but close. Vertical is right on. No matter what I do, I can't bring the red back to the left about 1/2". What the heck could be causing this?

[DaveWM]

can you post a pic of the convergence problem? with the cross hatch.

[Kamakiri]

Wasn't able to get a good one last night, but I did this morning. Also, as you can tell, it needs degaussing, but all I manage to do with my degaussing coil is make it worse.....

Picture is pretty watchable, but as you know, the crosshatch brings the issues to the forefront.

[DaveWM]

thats mostly a center converge problem. double check the posistion of the convergence cluster, should be able to correct with the RG magnets that are attached to small rotating knobs on that set. the RG are the ones on the sides of the cluster approx 4 and 8 o'clock. once you get the center convergence done the rest will be a LOT easier.

[DaveWM]

do you have the setup procedure for that set?

always start with the degauss then purity, then static, then dynamic with static touch up after each dynamic.

[DaveWM]

a few other tips

set brighness down some, make sure focus is as good as it can be, get up close to the screen to check, use a resistor to turn off the blue and focus on the RG, to the blue last.

[DaveWM]

not sure I follow about the degaussing coil making it worse, you need the purity good 1st as if not then you will waste your time on the convergence as it will be messed up when purity is corrected.

[Kamakiri]

Here are scans of the setup instructions. Bear in mind that I've never done this before....for convergence, I've pretty much just done a board setup (tweak the pots on the convergence board with a crosshatch and just get as close as I can). If you wouldn't mind walking me through the setup, I'd much appreciate it.

[DaveWM]

I ammended my post above, but most of that problem looks like static, fix that with the RG rotating knob type magnets. Use dots and only look at the center.

After the RG dots in the center are done (the move diagonally so you have to work both those magnets knobs at 4 and 8 o'clock at once to intersect) then move the blue dot up and down and side to side to land on top of the now yellow dots. Only the blue can move any direction so its last to adjust.

again only worry about the center. And you must do the purity 1st.

[Kamakiri]

Originally Posted by DaveWM

thats mostly a center converge problem. double check the posistion of the convergence cluster, should be able to correct with the RG magnets that are attached to small rotating knobs on that set. the RG are the ones on the sides of the cluster approx 4 and 8 o'clock. once you get the center convergence done the rest will be a LOT easier.

That's kind of what I was aiming for.

Unfortunately, I don't have a center dot setup, I only have crosshatch, white screen, gray scale, and color bars (using a test pattern DVD transmitting via agile modulator). One thing I should note, the purity rings on the tube have a light coat of rust on them, and to be frank, I'm not exactly sure *how* they work to begin with.

I tried rotating them on the crosshatch screen to try to affect something, but if I'm understanding this correctly, I need to do that on a white screen first.

[DaveWM]

The purity rings align the electron guns to the shadow mask, you side the yoke back, bias off the green and blue guns (or just turn down the screens), aim for a red blob in the middle with 3 green and 3 blue blobs of color around it. the rings have min effect when tabs are together, start there, rotate the whole assy to move the red blob AROUND, spread the tabs to move the red blob radially, do this until the red is centered. then move the yoke back towards the crt until the red spreads out and covers the screen. try each color (use the G2 screen drives one at a time to see if you have good color on each gun. Then you can move on to convergence. There are a few examples of this on you tube. call me later to discuss. its not hard and will make a HUGE improvement if the purity is off.


of course if the purity is ok you can skip this, just turn off all the screens and turn up one at a time and see how pure the color is to start with. You may not need to set it up.

The give away to bad purity is color shifts in different parts of the screen, like a all red dragnet scene that has purple splotches in the red, classic purity problem.

[DavGoodlin]

Tim, This is a great lesson here. I'm anxious to see how well this turns out, and it will too.

You get this right and you can converge any round-tube color set even better!

[andy]

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