Finally, the CTC-7 is alive!
 

After fixing the chroma issue I was having by replacing the crystal (and a tube socket, grrr), a little tweak to the killer threshold was all it took to get things going. I though something was still messed up, because the vertical streaking I was getting with the dot pattern was pretty extreme. Turns out all the controls on this thing are very sensitive, and it had to be set just right.

Color bars are still jacked, so I'm gonna run through the chroma alignment outlined in the manual tomorrow. That should be fun. :sigh: After that, greyscale, purity and convergence, I'll post up the results. It's starting to look good now, despite the crappy cell phone pics. :yes:

Your color bars almost look like a purity problem the way the color varies slightly in different areas of the screen - though it could just be the way the camera captures the screen.

Looks like your on your way to getting this set rehabilitated. :thmbsp:

Well, this makes me very happy-- especially since when I found it, it was a rescue set that might well have been discarded by its previous owner.

Just wish I had techs around here that were up to the challenge of bringing one of these old girls back to life... but I'm glad she found a good (well, actually a **great**) home! :thmbsp:

- Kevin

No you're right, it's still a purity issue I haven't gotten to just yet.

And actually, I have horizontal drive issues to work through still. Cathode current is still hovering around 212ma, where the manual says to keep it under 210. I'm gonna shoot for 160-ish just like I did on the CTC-9: so far I've adjusted the sine wave coil for 'equal peaks' as per Sams using the o-scope, next I need to check the drive waveform at the 6DQ5 grid to make sure it's at the correct amplitude. My guess is there are drifted resistors in the horizontal (drive) circuit, because even with the drive control at it's max, current is still high. Just in case though, Mark let me borrow his fly ringer to check for winding issues. I should have an update later today, after I get off work. :thmbsp:

Second the advice to do purity before considering chroma alignment. Also, check the color demods to see if one died - looks like you only have R-Y on the screen.

Edit - looks like only R-Y on the bars. I see blue on the program, but that could be due to tracking misadjustments.

demodulator issue
 

your photos look like a demodulator issue, if you have a scope check the b-y signal path, a purity issue would allow you to have uniform color bars

Go ahead and redo the purity process, but I bet you'll find the problem to be in the demodulator section, could be an open coil or just a bad tube, a scope is the best way to find out

Great job Nick! I'd like to come see this one in person, a 7 is on my "must have" list. Once you get the color right, it's gonna be awesome!

That could be, I'll check waveforms after getting horiz cathode current under control. Also remember that I had to mess with the CRT drives when I put in the other kine, so it's also possible I just need to redo the greyscale and all that stuff. It's all out of whack, no doubt. Main thing is I'm making good progress, and I have no doubt I'll be able to get this thing back up to par soon.

Mark, stop by anytime. I am on your way home from work...

That's great! I hope to start the second restoration of my blonde Anderson CTC-7B after Christmas. I've had it 38 years, and it's the first color set I bought. Been sitting a while, so 'lytics will need to be replaced.
Kevin:banana:

K, I did some poking around this afternoon on the drive issue. Some things went well, others puzzled me.

On the CTC-9 when adjusting the horizontal efficiency coil, the reading on my meter would drop as I turned the slug inward then start to climb again after a certain point. In other words, there was a midpoint which gave the lowest overall reading, and on either side of that cathode current would begin to rise.

On the 7, I can twist the slug all the way in till it bottoms out and current is still falling. This would seem to indicate to me that either the coil does not have enough range to get to a low (best) indication on the meter, or there is something else amiss in the damper circuit. I subbed the 6AU4GTA in from the 9's chassis, but the result was identical. Although current is now below the 'safe' level of 210ma outlined in the manual, I know it could be lower.

I did the flyback rining test with Mark's neat little Sencore unit, and everything looks good there. Drive waveform also looks good on the scope at the 6DQ5 grid, though I had to insert a 60k resistor in the drive circuit to offset a drifted 250k drive pot (it drifted low to 180k).

After all that, I did some looking in to why the colors were so wacky. Turns out the chroma phase transformer was a tweak or 2 away from where it should have been, so I nudged it to where it ought to be and now I have mostly correct colors. For some odd reason though, I can't get cyan to show up. I have decent magenta, red, green and blue, but no cyan no matter what I do. Also, the brightness control varies red and blue like it should, but when I turn it all the way down, I still get clear green bars...

It's not the drives either, it seems like the g-y amp is being driven when it ought not to be. Guess that'll be the next issue I tackle when I get back on it on Sunday.

The lowest current reading is the right setting and is also supposed to produce the best Horizontal linearity.

If you can't find a dip on the 7, look at replacing the resonating caps around the coil. Sometimes these have a 1500 volt rating.

Best Luck, Cliff

I just picked up a 7 remote set with a dead crt. can I replace the dual hv crt with a regular FJP?

Yes, but you have to add a .1uf cap on the heater (pin 7) of the 6BK4 to ground to prevent HV from destroying the windings in the transformer in the event of CRT arcing.

Funny you should mention it, I've never seen an actual change in picture linearity when messing with that coil. On the Philco B&W set I had though, it had a huge effect on screen images.


See, that's what I though too! But I tried replacing the .1 across the coil with a .047, and current ranaway to 250ma+ before I pulled the plug. After that I tried a .2, and it didn't seem to make any improvement over the readings with a .1uf cap. All the ones that are in that part of the circuit are what the schematic calls for right now, so I'm not sure where to go with this next.

I suppose it's possible that there are some funky turns on the efficiency coil itself, so perhaps I should try slaving in the known good one from the 9 next?

Nick. Is this the thread on the ctc7c I got from you in trade? Would like to post an up date on this set.
Thanks.
Ed