CTC-16 combo
 

Picked this up today. Wood looks pretty good, needs a good cleaning on the metal parts. 6JE6 had a short on pin 8, CRT is weak but at least all three guns are about the same weak and it does come up so I should be able to test it out. Looks unmolested (all the screws were in the back, and the chassis topside looks good). I will do the soft startup in a bit and see how it goes. Worst case is I have a CTC16 in a termite destroyed cabinet with a good CRT that woull make an easy swap. Tube tuner with a SS power amp.

ctc-16 combo
 

Great score Dave,congratulations. I have that exact same one i picked up last year, as well as a similiar one that my parents bought when i was a kid that i fixed up. Ive got a soft spot for these things, if you need any extra parts or any questions i can help you with, feel free to get in touch.BTW, the model is called The Stockholm and its SAMS folder 818. take care Bruce

roger that. I its on the variac so far so good. The chassis is super clean.

1st try, got audio so at least tuner is working, HV would not come up, I stopped it when the HOT current went up to 300ma. Will be checking for drive next. a quick check of the HOT grid with a standard DMM gave -35v. Should have been more neg, but that may have been the loading of the meter. I will put a scope on it and see hot it looks. I pulled the shunt off just to make sure the HV was not getting shorted to ground.

wow that is a nice set dave mine has been in storage I dont know when it will ever come back out

well, I checked the drive wave form good PP correct shape, then checked the voltage again, this time with my vtvm, hmmm does not go neg, double check with a VOM same thing, I think I was using the DMM and was seeing a +v grid not a -grid, damn digital displays. Well I smoke the DMM when I had it in resistance mode and connected to B+ argh so not sure what it is, but forsure the HOT grid has a positive bias. I let the tube cool off and, pulled the HOT and hooked up to the grid, the instant I plug in I get a surge of +vdc on that grid. It drops as the horz osc warms up. I figure the .01 coupling cap from the horz osc to the HOT is leaking. Will check that next. I just hope I can do it with out too much in the way of pulling the chassis out. Thats one thing about combo that can be a bear, all the extra wiring.

What's pin 8 shorted to? -35 volts grid is too high, and would no doubt cause the tube to overload. My RCA manual shows -56, so something's amiss. First suspect would be a drifted 10 meg resistor (R169), which would put a more positive voltage on the grid.

I think it maybe ok, I replaced the coupling cap, will reinstall in the set and try again. Prelim check on the bench looks good (cat current around 200ma). I am having some arcing from the HV rectifier filament leads to the cage, insulation breakdown, I will see if I can just dress them away for now and give it another try.

this thing must have been some tv shop's tube dumping ground, 12 hard shorted tubes, evey pcb effected (even the tuner had a shorted tube) mostly off brand tubes (not orig rca's).

I am pretty sure I have all of them. there are one or two questionable looking caps some dipped caps that look like they have gotten very hot at some point, one sits right next to a power restor. The resistors look different from what I have seen on a lot of sets, they seem like they have a courser appearence, some of them are very hard to read, the color bands have degraded, not sure if its from heat or just age (I think when new they prob did not look all that great), but they all test very well.

I have seen several shorted tubes in sets that sat unused for years. I wonder if its whiskers? Can whiskers form in a vacuum?
I have had good luck banging the tubes on the table or blowing the shorts open with B+ voltage. They never seem to reshort.

I remembered you exp with fixing the shorts, was trying that as well, no luck.

Aw man, we sold a number of that exact model combo 'back in the day'. Seeing the pics makes it seem just like yesterday.
Trusting y'all already know about reflowing the two ground stakes on the far right end of the chroma board. They go open and kill the heaters on the 6GU7's.
Bill(oc)

thanks for the heads up old coot, I will def do it.

Dave.... Dave.... Dave....

If you keep finding all the good stuff, there will be nothing left for the rest of us... Just kidding...

One of my neighbors has this same set in the basement. I've been trying to get it for years. Her dead husband bought it, so it's not going anywhere. I've gently reminded her kids that I would restore the TV if they ever decide to let go of it.

ctc-16 combo
 

When i picked this up last year and removed the CRT for cataract repair, it was without a doubt the easiest removal i ever thought possible, the safety glass literally stayed on the floor when i lifted the tube. I hope you have fun with this Dave...

I like how the bezel on that one is green, just like the CRT.

oh yes much fun, I have to say this hobby keeps me sane this time of year.

I did manage to check that one CRT grid coupling cap (it was very dark in color unlike the other two) sure enough it was weak on the cap tester. Prob would not have made a diff but what the heck. when I get some time I am going to go thru my pulls and see if I can find some tube for the shorted ones.

The HV has a leak from one of the HV tube filament leads to the HV case. I am going to just get some plastic and dress it away for a temp trial.

cleand up some gunk off the front bezel, looks better already, looked like years of smokers tar accumlation. Got most of the tubes from my stash still need a few more, I am sure I have them, just have to dig. I am trying to use up my stash of pulls, saving the NOS since they are boxed and neatly stored.

I am tempted to get some silicone caulk and carefully coat the filament leads around where it was arcing. It would be easy to get at since it was in the middle of the lead coming down from the HV cup (mounted on top RCA style).

THats what I did on a heathkit GR-295. Silicone works like magic!

I will stop by the store and pick some up. I always end up with a tube in a gun thats solid, maybe I can find a small squeeze size. I really dig the way this thing looks, for a combo its quite pleasing.

Ill pick you up a few feet of that wire next time Im at the electronics store.

You could pull those two wires out of the socket and put several layers of heat shrink over the bad spot but even that is tacky.

got the last of the tubes, just have to find a few minutes to put it all back in and see how it goes....

I did not even check the 3A3, swapped in one from a working set, and I got a full raster :D 25kv at about 185ma

going to check the one just to see how it checks out.

Almost time for the rockford files will be hanging it up for a while

checked it the 3A3 had zero emissions, did not see the filament light up.

1st screen shot. The tint is off but the control works I just did not bother to set it correctly. this pic was taken in a VERY well lit garage, so that old CRT still has some life in it.

Congrats, looks like it will end up being a decent performer!

185ma.@ 25KV. That is a healthy sign indeed. Back in the day, if we could get it down to 200ma. with good width and regulation, it was considered a good portent of longevity.
Bill(oc)

wow and the color works without having to change the crystal, go through 5 different 6gh8s or tweak on the coils.

what odd is I dont really know why I had the orig high current, the only thing I did was to replace the HOT coupling cap (the .01 tested a bit weak on my cap tester but not much just a little, certainly not enough to resolve this)

I think what was going on was the HV filament lead was shorting to the chassis, when I pulled it out an bench tested iit I could see/hear the arc.

after dressing it away from the chassis (short term fix) the arc resolved and the HOT current came down. I assume this was the base problem with the cathode current.

focus on that 1st pic was not very good. I plan to check the focus tube (1v2) and will check the focus voltage at the CRT.
and need to check the contrast control to see if its effective, maybe a weak Y signal (has all the orig eletrolytics, so I was thinking maybe the 12BY7 cathode bypass cap). I have seen low Y result in loss of detail.

finally I have to figure as bad as the cateract is, that has got to be hurting the pic some.

well now that it has base line working status, I will pull the chassis and check all the can caps. I am pretty sure the main filter caps on the B+ are ok as the ripple was normal, but I know some of the other sections are ofter used for bypassing or decoupling and can cause odd problems. Considering its age I think its prudent to at least test them while I have it all apart. That will also allow me to do a through cleaing of all the dust and crude inside the cabinet. I will also clean and lube the tuner while its out.

Dave that set is sweet.I can't understand how you find all these,as I am in Florida too,and have never found a roundie in the wild .Great find!

tested 1 can all sections test fine, second can 1 of 4 tested tested fine, did not get to the others, but I suspect they will be fine as well, 3rd can tested 1 of 4 tested fine. will check the others later but I suspect they will be fine as well.

checked the .001 2kv plate to ground cap on the Vert out tube. its one of those hard white shelled caps. It tested correct for value, but the eye would only null to about 3/4 fully open. On leakage again it would not fully open, and that was at 450v. All I have is some 1.6kv dipped caps. My guess is they are prob better than the 2kv that were in there when they were new, but I will prob go ahead and order some anyway if I can find them.

There is a .001 plate cap on the 6aq5 that is also a 2kv, argh...

I have some 2kv .001 disc caps but the one in there are 10%. I dont think it would matter on the audio, but not sure about the plate to ground on the vert out.

I added a micro sized fuse holder right by the horz out tube socket for the cathode of the HOT. I have a 300ma fuse in there. I also bypassed the fuse with a .1uf cap. With the cap in place it should be very easy to check the HOT current, just pop the fuse out and hook up the milliamp meter. I dont know if the cap will have any effect on the fuse, I know there is some voltage drop across it in operation, not enough to effect the HOT bias, but maybe the pulse could cause a false blowing of the fuse? fuse fatigue?

anyway I think I will now check to see where the takeoff for the B+ is on the pcb (its on the audio board) and see about putting in a line fuse there as well.

I went ahead and replaced that 2kv 001 with a disc cap, and pluged it all back in, still get a good raster, did not have time to hook up the tuner, so at least I did no harm to the HV with my HOT cathode fuse mod.

let me make that sound nicer, you need to invest in some of those square chemical fuses if you want to protect the set and dont want the fuse to open from general use :D

I wish I had my camera (AWOL) I cleaned up the knobs, reinstalled the chassis, hooked up the audio, did a brief center converge (OTA pics), set the gray scale up, after a few minutes it makes a very nice color pic, excellant flesh tones, deep colors, etc...

Sound is good as well (I had not tested that since I had to disconnect the speakers to get the tuner into the service position.

the CRT is weak but does come up after a few. I am looking forward to pulling the cataract out to see how much nicer it will look.

I am going to give it a rest and tackle the SS power amp, I only had one channel, not sure if it was the amp or the tuner. Have not tried the TT to see if it spins.

I did a real quick rub down with some restrofinish, looks a lot better, not sure if its worth the effort to restore the wood work. I have not done much of that, I may choose a set that is not as cool looking to start off with my wood refinshing skills.

I hope the phono cart is not DOA, they are hard to come by and pretty expensive considering what they are.

Tell me about it... I flew to a different continent to get a replacement ceramic for a crystal cartridge :D (well, I was there on vacation and took advantage of it... but that explanation doesn't sound anywhere near as impressive...)

Good luck with the resto- I love reading about other people's repair stories.

well the SS amp was in pretty good shape, used compressed air to blow off the 45 years of dust, yuck...

it had two .0027 paper caps on the input, both leaky, hope they did not fry the transistors. Two small 10uf coupling caps were leaky and had a high ESR, replaced those, there was one 40uf 250v cap that was a bit leaky as well, and a single 500uf 50v cap (think it was a bypass cap for the power transistorss) was leaky. the rest were ok (a couple 500uf 50v on the output and a triple section 250v filter cap for the tube stereo power supply).

anyway will try it out tomorrow, at least can test it by touching the tape input and see if both channels work.

the tube stereo will def need some work, there were paper caps in the MPX board, so at the very least those will have to go. The AM was working but the FM was dead. Did not check anything at all on that, so maybe just a dead osc tube in the FM tuner.

well of course there was no way I waiting until tomorrow. guess one of the leaking B+ caps may have been the prob with the FM, as it was working fine now and both channels sound nice and clean. the MPX light is working but I did not try to see if there was actual separation in the channels. I wil pull the radio chassis tomorrow and replace those caps and give it a general going over. The face plate is VERY dirty, so I will clean it up when I pull the stereo. I can see some of the silver paint is warn, not sure how to fix that, but maybe on of those paint marker pens may do the trick.

this thing really bumps....

well about out of gas, replaced the two papers (leaky of course, just checked for the heck of it) and 3 eletrolytics, all tested with high esr, could not check two of them for leakage, too low a voltage, like 5 and 15v my tester only goes as low as 25v, but they needed to go anyway.

Cleaned and oiled all the moving parts, scrapped of some mild rust spots that were on the metal face where the dial pointer slides, a little lithum there just to smooth it out, oiled all the pulleys etc... cleaned the pots and switches.

cleaned the white plastic back part of the dial face that obscures the chassis when reading the channels. the chassis was very clean. I just find it hard to understand the usage of those dumb paper caps, I figured they were stopped by the late 50's

more progress today, the stereo tuner faceplate cleaned up very nicely as did the knobs, hot soapy water and an old toothbrush did the trick.

on the plastic there is lettering that stands proud of the backing, RCA, new vista etc... was silver but much of it was worn off. I think If I can find or fabricate a small rubber J roller with the roller made from fairly hard rubber, I could just use it like inking lettering with some silver paint. I dont trust my hands to try and touch up with a brush, and since the lettering stands proud, I am pretty sure it would turn out nice.

Going to clean out the bottom of the cabinet under the tuner today and reinstall, hopefully the stereo will not need any more work as its a bit of a PITA to hook it up to the amp and speakers. Pretty sure it will be fine. I have worked on other RCA tube tuners, they work very well.