CTC-4 Director 21

[SwizzyMan]

Starting to think this may need an audio alignment. I can fine tune in a clear color picture, but the sound isnt there just the loud buzz of the modulation. When i turn the fine tuning knob to receive sound, the picture gets a lot of interference and the swirly lines show up. In other words the audio is not at the same tuning position as the clear picture signal. I suspect an audio alignment may be necessary.

[miniman82]

Hope it's not the same issue mine has, the audio went totally kaput on it one day and I think the IF can has an open winding or something. I can twiddle any slug I want, all it does is sound like a radio not tuned to any station. Gotta dig back into that thing at some point.

[Phil Nelson]

Originally Posted by SwizzyMan

the audio is not at the same tuning position as the clear picture signal. I suspect an audio alignment may be necessary.

Is there any fine-tuning spot where the audio is loud and clear? (That would rule out silver mica disease and show that your audio section is basically OK.) On some sets where the audio has separately drifted away from the video, you can "walk" the audio alignment back into step with the video by carefully tweaking the audio adjusters while watching and listening. This is lower-risk than attempting a full-dress alignment of video and audio IFs.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[Electronic M]

Originally Posted by MRX37

"Ahhhhh! Patrick! The screen looks like a fishbowl and I see wavy lines everywhere!"

Now that the picture loads....

I think this NEEDS to become a VK web meme!

[SwizzyMan]

Just put in an order for the filter caps. Hope to get started this weekend!

[dtvmcdonald]

Unfortunately this problem sounds like a bad main IF alignment, or else a fault
in an IF can, after fixing of which an alignment is needed.

Despite what some people say, every single postwar set I have has been
seriously out of alignment, even if it "worked OK". The picture quality and picture-sound tuning spot coincidence has been improved by either a tweek or
full alignment. If you tweek, only tweek one adjustment and return to original if
it does not completely fix the problem ... hoping that one big tweek and
one little one will 100% fix it is well on the road to Hell.

My TRK-12 was spot, perfect, on. If I could feed its video into a CT-100 it would produce a perfect color picture. The TT5, pretty much per spec, but a one-coil
tweek made it look better.

[miniman82]

Here's a thread talking about the circuit mods, BTW.

http://www.videokarma.org/showthread...=256638&page=2

[bigaudioal]

Thanks very much!!!

[SwizzyMan]

Pulled the chassis tonight. Multiple repairs have been done. You can tell it was owned by a repairman. I have already started recapping the filter caps. More to come later.

[SwizzyMan]

It's amazing what a bit of tarni-shield and elbow grease can do!

[miniman82]

Wayne,


This is a problem with all 5 chassis, including the Deluxe ones unfortunately. The problem is the flyback, it's got a lot more primary resistance than other models. This means there's a practical limit to how much current the HOT is able to sink, which in turn limits how much HV can be made in the secondary (lower current primary pulses means lower amplitude flyback rectification in turn). I'm not sure why this was done, but it appears to be in the design and intentional. Perhaps the engineers wanted it to be 'safer' or something, we'll likely never know.

I have a few different flybacks I can try in my Wingate (CTC-4, CTC-28, CTC-15), but the problem is not getting more HV or a yoke inductance match from the swap- there are ways around both those problems. It's getting all the ancillary circuits to play well with the new transformer that's a big question. None of the tertiary windings that provide pulses to circuits like burst gating or AGC appear to be common across chassis to me, which makes the job of adapting them much harder. Some flybacks had positive going pulses, some negative. Some had very high amplitude AGC, some not. What I see is probably a matching/inverting network and possibly some slight phase shifting to make the new fly work. It won't be a plug in deal unfortunately.


BUT- the payoff would be a very nice chassis indeed. The deluxe sets had good circuits in them for color processing, they just had a wimpy horizontal output transformer. I'm going to give it a shot at some point, and I'm also going to try primary side pulse style HV regulation. It'll be like reengineering a complete section of the chassis.

[SwizzyMan]

Still have 2 more filter caps to replace, but I thought I'd do a power up to see where I'm at. Current draw is about 2.5A and only putting out about 3 KV. I don't believe the HV readings since the yoke is not plugged in and all I'm using is a piece of wire to short the yoke connection so the HV will actually come up. Found a 80 uf in place of a 40 uf in one of the filter caps and most of the hacked in filter cap replacements had shot their crystallized goo out the side already. Things are going well!

[Electronic M]

Personally I'd pull the H output tube, till the recap is done and the osc. has been dialed in with a scope. Don't want to risk your flyback. On my 4 I did it that way, and when I was ready to install the tube I had it set up to dip the cathode current using the linearity/efficiency slug as soon as I had HV....I pretty much confirmed I had decent sweep and HV then immediately dipped the current. If something is wrong and the fly is being fed too much current, you don't want to run it that way long....We refer to flys for early sets like this as unobtainium for a reason!

[SwizzyMan]

Originally Posted by Electronic M

Personally I'd pull the H output tube, till the recap is done and the osc. has been dialed in with a scope. Don't want to risk your flyback. On my 4 I did it that way, and when I was ready to install the tube I had it set up to dip the cathode current using the linearity/efficiency slug as soon as I had HV....I pretty much confirmed I had decent sweep and HV then immediately dipped the current. If something is wrong and the fly is being fed too much current, you don't want to run it that way long....We refer to flys for early sets like this as unobtainium for a reason!

Amen to that! Only had it running 2 minutes. Still a bad idea on my part. I already heard john h's horror story with the flyback in his 4.

[SwizzyMan]

Replaced the seleniums with 1n4007s. Did a 30 second power up. Once the relay to turn on the HV switched on I blew the 4.5 A fuse. I double checked the polarity of the diodes and they are correct. Im thinking I may need to add a dropping resistor.