#1
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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.
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#2
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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
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#3
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roger that. I its on the variac so far so good. The chassis is super clean.
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#4
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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.
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#5
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wow that is a nice set dave mine has been in storage I dont know when it will ever come back out
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Audiokarma |
#6
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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.
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#7
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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.
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Evolution... |
#8
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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.
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#9
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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. |
#10
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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. |
Audiokarma |
#11
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I remembered you exp with fixing the shorts, was trying that as well, no luck.
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#12
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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) |
#13
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thanks for the heads up old coot, I will def do it.
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#14
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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. |
#15
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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...
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Audiokarma |
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