That CTC-11...
 

Hey guys, Gary called me tonight and I went to check out the 11 he got.. Guess he powered it on a variac even though it has been ran before. I brought my tube tester. Half the tubes in this set are Zenith, realistic or GE... Well, sounds like the flyback makes these loud sqealing noises and the crt goes berzerk.. We unplugged the set. I told him to order caps and get out his ESR meter... BTW, that set has an 21FBP22 in it, he tested the emission at 85%red 90%blue 91%green on a bk 466. What causes this sqealing, it only did it once upon startup... It was nice and loud too!

by bezerk, did the picture tear off into little strips? Could be the horiz. oscillator freq. is off

the core of the flyback could be loose and causing that squeal

the HO tube could also be making that noise. I have a zenith that has the high pitch squeal. HO tube is the culprit.

get it fixed before you run it again.

No the pic just went to big white bars. this noise was abrupt and lasted half a second. All tubes check out great. The sound was more like a shreeking screech...

Check the HV box and make sure all the HV areas are clean. Might be flashing over - that'll kill the picture and make lots of scary noises.

shielding
 

make sure all the factory shielding is in place around the IF sections, I had a ctc 9 that showed the same syptom, when I put the bottow shield back on the bottom of the IF section it worked fine.

Cool, Ill check it out tonight, we found some bad caps in the filter section.. Going to replace all caps. Also some wax caps in the Demod section have no ESR, going to replace those too... Ill keep you updated. I want this set! Im trying to buy it from my friend.

Well I found a puddle of wax under the flyback. Im assuming this is normal.. the flyback looks dry, but could use a recovering, I was thinking about doing this to my ctc-16, whats some good stuff to use?

A puddle of wax indicates overheating. I use low-acid type RTV silicone to recoat the flyback.

Make sure you check to see if the HO tube and Damper are good and adjust the HO cathode current. No more than 205ma or it will run hot. If not attented to it will kill the flyback. YOu also may want to check the HV regulator current and adjust the HV using an appropriate HV probe and high input impedance meter . Should be around 24-25kv with brightness at minimum.

Ok well not to sound dumb but how do you check the cathode current, can I use a dvm? and which pins to I check the current at? And in which condition should I check the current, set running with the tubes pulled or not and Where can I find a HV probe, and in that since how do you check HV?. These are the only things I dont know yet... I have to do this to my ctc-16 as well.. 300 bucks and the 11 is mine... ouch... I only have room for one more set and I want a rectangular set...

The sams should be able to point out the exact procedure for the cathode current, and some sets (I think the 16 chassis has it) have a jumper you remove to connect the ammeter between the jumper and ground. If you don't have the sams, disconnect the cathode lead from the HO tube at the socket and connect your meter between the cathode pin and the lead you just disconnected. THe tube has to be IN CIRCUIT and the set running to do this. If your DVM has a provision for measuring current in milliamperes it will do fine.
This procedure can be a pain if if the cabinet doesn't have a removable bottom, and its even better if you have a test jig so you can operate the chassis out of the cabinet.

Hv probes come up from time to time on ebay. I got my fluke for about 20 bucks shipped and it works well. YOu just need to make sure your meter has a high input impedance or it will cook, at least 1 meg ohm. YOu connect the meter to the probe, and the ground on the probe to the chassis. Carefully slip the probe under the cap and touch the HV lead. Adjust the HV control for hte proper voltage at minimum brightness.

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Well I just bought a HV probe, EICO Model HVP-5 with meter built into the probe.. Hope it works.. Thanks for the help guys.. Youre awesome.. BTW, how do you adjust HO cathode current? I know how to adjust HV..

Cathode current is adjusted with the horizontal efficency coil. It should be labeled on the chassis. Use a plastic tool, and do not force it or the core could seize up in the coil.

Bill R

Awesome!!! Thanks guys! There is a 250v 160mfd cap in the can cap to the right of the black beauty shorted, no reading on my esr, goes way high, unreadable on the 200mf setting.. This could have been a cause to the shreeking (very loud noise) that came from the area of the flyback... But not too sure, looking for a sams for the ctc-11 still...

You can just about guarantee that all electrolytic and paper caps in a forty or fifty year old set will be bad. If they haven't failed yet, they will soon.

It's hard to resist the temptation to power up a set immediately, but it's more prudent to replace the filter electrolytics first. Powering up on a variac offers no real protection against burning up an expensive power transformer. Yes, I have done that, and it cured me of the temptation forever.

Some old electrolytics may "reform" after a fashion, but they are not reliable to use for the long haul, in my experience.

It's also a good idea to carefully clean the HV section, as nasadowsk suggested. HV can do funny things, especially in a set where HV components are coated with carbonized cooking grease & tobacco residue. I would do this even if you are not currently experiencing Bad Things from that section.

I have a CTC-11 on the workbench and a copy of the Sams. If you send me an email by going to http://antiqueradio.org/contact.htm , we can figure out how to get you a copy.

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

email sent, Thanks Phil!!:thmbsp:

Hey Guys, here is a head scratcher...

I overlooked this the other night. In the HV cage, where there is supposed to be a 3A3 there was a 3DJ3..
The difference in these 2 tubes is that the working plate voltage of the 3A3 is 47vdc. The 3DJ3 has a working plate voltage of 25vdc. What would be the reason for someone to use the 3DJ3 HV tube and does this cause any issues with the set? The tube is still reading barely in the green if I test it as the proper 3DJ3, but testing it as a 3A3 it goes way into the questionable are, of course..

assuming the pinouts are the same, the 3DJ3 is NOT a god sub at all. Its going to have a short life trying to act like a 3A3.

Wonder who changed it out and why they used an incorrect sub.... :scratch2:

Im not sure but there is a slight difference in the pinouts, although they all corrospond to the proper pins the 3DJ3 has a wire from the (filiment)? coming off pins 2 and 7 going to pin 1 where the 3A3 does not..

The other thing I noticed, there seems to be no inrush limiter in tis set anywhere, but it doesnt have a degausing field either... So maybe it's not used?

The other thing I noticed, there seems to be no inrush limiter in tis set anywhere, but it doesnt have a degausing field either... So maybe it's not used?

The auto degaussing didn't come in until the model 16 IIRC

Oh my bad.. :screwy: you learn something new every day, still dont know why this set has no inrush limiter, but it operates.. Here's a link to a thread started by Wcarrol and a pic shows the inrush limiter there on his ctc-11, where it looks as if either mines missing or that it never had one.. :scratch2:

it's 8 posts down on picture 3

http://www.audiokarma.org/forums/sho...ghlight=ctc-11

Could have been it was broke and rather than replacing it with the right part they just bypassed it like smart people ;)

kinda like replacing the 3A3 with a 3DJ3 :no:

Yikes, didnt know you could bypass these... Is that safe? I know the one on my 16 is broken, I have it held together with a shower curtan hanger! (Redkeck inginuity)!!

Its hard on the power supply tranny and caps to bypass it, not to mention the power switch!

I would get a replacement.

Well good news on the set, we ( I ) recapped it yesterday, all filters and some throught the chassis. All lytics are swapped out, nice (i mean breathtaking raster) better than my CTC-16, deep and rich contrast and I converged and adjusted yoke and purity degauss. Then I noticed the vertical shrinking... Probably out of tolerance resistors. But I picked up a toy for me today, look in rectangular forums under maggie console, so time to work on my own set!

good to hear its coming along well. I think he should pay you for your work, or at least offer to sell it to you for less :D

Yeah man seriously!! Im thinking to myself.... Dude if I am going to do the work, supply beer !!! But it's time for him to work on his own tv. Maybe ill give him help, will work for pizza, beer, money!

What is it with the vertical circuits of these old CTC chassis, it seems that every one of them have some problem, I looked in the vertical board for some resistors that may be out of tolerance, only 2 of them are reading 10% over, now usually when they read over I juist replace them. If they read under, usually it'sbecause they are in circuit and something is drawing down the resistince. All the caps seem to be ok on an esr meter. What has happened is the Vertical height is lacking about an inch on the bottom, about 10 minutes of being on the height dramatically squishes down on the bottom, and stretches on the top but shrinks as well making my think it;s in the linearity circuit.. I did change the resistors that go from the lin and height pots to the chassis though to no avail.

I've not had the troubles you're having with the vertical. Sorry to hear this set is being such a difficulty.

An esr meter measures equivalent series resistance. A cap may measure low ESR, but can still be bad. Just touch the wire of the ESR meter together and you get a good reading --when its a short.

At times, an bad cap cap will have good ESR readings, because it is leaky or shorted. This can be verified with an old analog VOM or VTVM. These meters use a much higher voltage than a DMM, ESR, or standard leakage meter. I use an old RCA VOM that has a 25v battery. When I set the resistance measurement to Rx10, its putting that 25 volts across the cap to measure its DC resistance. Because the 25v is much higher than 3, 6 or 9 volts, it is more likely to show a leaky condition rather than at a lower voltage which may not reveal the flaw. A real capacitance tester can put the rated voltage across the cap, in some cases up to 1kv depending on the model. This will definitely reveal any fault with the capacitor. Most of the time old caps just become leaky, or turn into resistors all together.

don't overlook ceramics or mica caps. True, they have a lower failure rate but they do die. If it only happens after warm up, then its a temperature related failure. You can buy a can of freeze mist and lightly spritz the components in the vertical osc and output sections while watching the screen. Pause between components and notice change. When you see a difference in picture size you've found a bad component. if you don't have a can of freeze mist, you can turn "can of air" upside down and spritz away.

A great thing to find if you like working on these sets is a test Jig. This is essentially an external CRT and speaker, and a bunch of extension cords to connect to the chassis while its out of the cabinet. They even have adapters so that you can run a round tube chassis on the rectangular CRT test jig. This makes it MUCH easier to troubleshoot the chassis, especially critical voltages around the tube sockets in the vertical section as in your case. They pop up from time to time and are fairly cheap. You might poke around TV shops in the area to see if they have something like that they would sell you.

Before I found and bought my equipment, in your situation I would simply compare voltages on the schematic and shotgun the offending section. See if the B+ lines on the vert osc and output section are within spec. If they are a little higher I wouldn't mind it much, but if they are lower, especially after the warmup look to the power supply.

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Yeah, that all makes since guys! I really do apprecialte the help! Im going to have to put this to the side, as my friend gave up on it and sold it to me..

now you have another roundie!! i envy you. my 15 had vertical issues too. centering pot was gone and it had a double resistor set up to the linearity control that caused the top to expand - created coneheads! i cut out both resistors and cured that problem. then the service switch went up in smoke! it is on the back burner now. i will get to it someday. those vertical circuits in those old tubers. i need to learn more.