Rca ctc-5

[DaveWM]

put a new 6U8 in place of the 6EA8 that was there, (sync sep) fixed the sync and now the AGC works as it should. Only thing left is to setup the purity (screen colors are all over the place with HUGE convergence issues), but its coming along.

[DaveWM]

I did not even touch the convergence magnets so that should help some, but I still need to fix the yoke plastic AND move the CRT to the new cabinet.

[DaveWM]

oh so there are no PM for static, instead there is DC pots, thats something new to me. I can see how this should be easy to setup with evey thing out front.

[old_tv_nut]

Originally Posted by DaveWM

oh so there are no PM for static, instead there is DC pots, thats something new to me. I can see how this should be easy to setup with evey thing out front.

Good luck on the pots - all three were burned open on mine, and 2 of 3 someone gave me from a donor chassis were also. These are special 100 ohms tapped at 25/75, esentially unobtainium. It was a poor design since this is at the low end of what carbon comp pots can do resistance wise.

The problem is that the tap is used to set up a zero-current point so you can go plus or minus. The only way I could get it to work with an untapped pot was to use two pots with a toggle switch to select if you wanted zero to plus or zero to minus. It seems like it would be easier to use the convergence coils from a later set with the permanent magnets, but I think they are wired differently for dynamic convergence too, so won't just drop in.

[DaveWM]

contrast was a bit low, I had a new video out tube already, so a new 1st video amp and now the contrast is very good, can go from little to too much now.

I was trying to set up the purity so tried sliding the yoke back, and killing the green and red grids with 100k resistor to ground, when I powered it up, no HV. Popped a 3/4 fuse. My guess is I must have shorted out the yoke somehow. I monkeyed around with it some more and tried a new fuse, and got it back. I adj the purity and slid the yoke forward, got a nice full red screen. I am not sure what happened on the yoke but I will not mess with it again until after I have moved the CRT and fixed the plastic. I have a spare yoke so will experiment with it on making up the plastic piece. that way I can keep working on the set while getting the spare yoke ready to go. The center convergence is pretty good now, but the dynamic is still way off.

I have not yet tried adjusting the eff coil for lowest current. IIRC the service manual has you checking the voltage drop across the cathode fuse. I think I will just use my fuse adapter and plug that in with the current meter in place of the fuse to dip the cathode current.

[DaveWM]

I have a donor chassis as well, so hopefully I can get it right. but since the center is looking good I may be ok.

[old_tv_nut]

Originally Posted by DaveWM

I have a donor chassis as well, so hopefully I can get it right. but since the center is looking good I may be ok.

Don't mean to be a party pooper, but the dynamic convergence circuits in this chassis are AC coupled - so when you move the edges up, you move the center down, etc. Some point about halfway to the edge stands more or less still. It's an interative PITA to get both static and dynamic. Start by doing dynamic to get lines to be parallel, then do static, and repeat.

[wa2ise]

Doing convergence on the production line for those sets must have been a nightmare. One thing manufacturers hate is having to fiddle with product, they prefer it if they can just stuff circuit boards and have it work with no adjustments. SAW filters in TV IF strips was very nice, no alignment needed.