Ctc-16
 

thought I would start a new thread now that I know the chassis I have.

this is my 1st early color. when I got it I started a slow power up on a variac (metered). when I saw 1 amp at 10v I knew there was a problem so stopped there.

I disconnected the B+ from the bridge rectifier, powered up again, no problem think it was about .7 amp IIRC all filaments (not the crt the chassis is out on the bench at this point). came up.

B+ was about 400v disconnected. The resistance at the 1st 80uf cap was 24 ohms :no:

I started with the easy stuff the filter caps were in pretty good shape (tested with a cap tester for capacity and leakage at rated voltage).

moving a long I started unwrappping various B+ feeds to thinking maybe a shorted bypass (not likely since mostly dipped caps, only a couple of the HV ceramic tube types and the were ok).

last thing I check (prob wishfull thinking it was not the problem) was a transformer behind the HV cage. I assume it is a vert output, but it also drives the convergence board. Being new to color I am just guessing about this.

anyway it has 5 primary and 6 secondary winding. Two of the primary windings are green and green with yellow strip. the GY connects to the 400v B+, I also disconnected the other G on the primary. doing this removed the 24 ohm reading and now I get 8k

At 1st I thought I had a short in the transformer from the primary to the secondary (there is a lead on the secondary that goes to ground).

but I still need to trace the remaing 3 primary leads (blue/red/yellow) to make sure they are not the problem. I hope to pic up a RCA service folder today to aid it the tracing.

primary side blue and red seem ok, the yellow which goes to the yoke has 2 ohms to ground. I am going to have to stop and go get the service manual, just not sure what the internal wiring of the tranny is...

Which CTC-16 do you have? The earlier style or a CTC-16Xx chassis? I'm not sure offhand what all the differences are, but I know there's different Howard Sams for 'em.

Oops, nevermind my chassis question..I noticed your other post. I have a CTC-16 E that I've had since the seventies that still works but I need to refurbish the electronics and deal with a few quirks.

I like the fact that the later versions (like yours) came with the RCA "Hi-Lite" CRT which is an awesome picture tube when in good condition.

got the schematic, not looking good on the vert output. the primary is green,green white,yellow. with all those out of the circuit I still have a low resistance reading to the chassis.

Moyers had it so its on the way :banana:

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getting ahead of myself, but I would like to make a simple box cabinet with some nice thin legs for it. The old cab is shot.

reading the service manual it says about setting the tuner in the service position, I cant seem to figure out how to bolt the tuner or in some other way to place it on the chassis to make working on it easier. I am guessing there is some way to attach it to the chassis to reduce the awkwardness of the two parts.

Yeah, there are a couple of screws/small bolts near the AC line plug line in. The tuner will fit right into those screws.... knobs facing upwards... and then you tighten the screws. You can leave it there and do all you need to the chassis out of the cabinet.

got it thanks Charlie!

while waiting for the vert out xformer I went ahead and repalced a singe 50uf 150v cap (tested leaky). I am going to give the big can caps a chance to reform I just want to make sure it works and the CRT is ok before going thru the effort to stuff them, They are not shorted, I will monitor the current and see if they come up on the variac when I get the B+ worked out.

Tuner issues, the UHF can be tuned by turning the dial indicator no problem, but not with the tuning knob. If you push down you can fine tune the VHF, but when not pushed down it engages thru a series of gear to the UHF.

It seem that the alum gear is seized to the shaft. What I dont get is how come the UHF can still turn with that alum gear seized? My guess is there is just a friction coupling that normally works when the alum gear is not seized up. It also looks to have some kind of built in gear lash control.

I looks like I may have to remove the lashed gears on the tuner in order to get access to the screws that hold the alum gear assy to the tuner box. then I can work on getting that stuck gear off and re lubed.

Dave,

What are your tuner numbers? KRK... Is there a TMA number on the tuner cluster? I have an RCA guide on almost all of the RCA 60's and 70's tuner assemblies with breakdown of the mechanicals. I can get a copy of the UHF area for you if I have the above info.

Lots of questions, I know - and one last one? Where are you located? Most of us have our location listed in our profile - helps with the local help...

Cheers,

TMA 96A

updated profile.

Got a hickok 533 tube tester today to play with looking for a manual.

.....and me just back from Lake Buena Vista!!


I'll look tomorrow for the TMA info.

Check the Boatanchor Manual archive (BAMA) or it's mirror for the 533 manual and tube data. 532, 533, 534 and 600 all share the same tube setup manual.

Cheers,

thats about 15 min from me. hope you had a good time. I get up to VA now and then, near DC (centreville)for work.

fingers crossed should be getting the vert output today....

got it:banana:

now about hooking it up, I guess the smart thing to do would be to make sure I have the exact same wire colors before doing anything.

Make sure the match up to the schematic

cut them off the bad xformer fairly close to the xformr so I can use them for lead dress examples when I replace with the new.

does that seem reasonable? never had to replace a tranny before.

Yeah I'd cut them close to the tranny, too. Sometimes they give you just barely enough to work with.

Keeping our fingers cross!

the plan is to spend some quality time on it tonight, prelim checks show the new one is not shorted so I am pretty sure I have a correct diagnosis.

I wonder if it spontaniously shorted or if there was some defect in the vert circuit thay could have caused a short....

if that was to happen I assume there would have been a spike in current. I think i will double check the vert output tube before firing it up. look for shorts etc...

hmmm looks like that short 9 pin fat tube is the vert output. It is the one with the leaky 50uf cap (replaced it) if that was a cathode bypass, then the leak may have reduced the bias and caused the tube to pull too much current thru the load (primary of the vert trans) of course I dont think I have the right tube tester for THAT tube :no:

yep thats it a 6GF7 dual triode, and that was a cathod bypass cap. Oh well, I can wire it up, but I think I will hold off power up until I can get that tube checked for shorts, prob ok but I jsut would hate to toast the new tranny.

sams and RCA service man both show about -55v bias on the vert osc output grid, of course they show diff voltages for the grid and cathode but both net to about -55.

The sams shows a 38ma current thru the cathode, no way to read that directly but I guess I could determine it based on the V drop across the cathode resistor..


hmmm scratch that not that simple, I was reading something wrong. This would be a nice time to have a test socket that you could jumper each pin on or off.
not a tube extender but a tube extender that you could make/break the pins for current readings. I dont know if such a think exist.

Make sure you check the vertical center control. I have seen them short to chassis ground and burn out transformers and the power supply.
Ed

I will check that thanks.

well it went fine, tranny in, did a slow power up on the variac with the vert and horz tubes pulled. got up to about 250ma I think the sams says about 400ma but of course I did not have the horz/vert operating. The cans stayed cold so hope that is all good.

Will check that vert center pot (did the power up before reading that post).

one odd thing there were two color coded wires that went to the convergence plug that were not "right"

the schematic called for

Grn Red pin 5 .8 ohm
Blk Grn ground
Blk red pin 4 1.5 ohm

blk grn is the center tap of the other two.

the resistance measurements did not jive I had to reverse the pin 5 and pin 4 connections. I confirmed the resistance measurements against the old tranny. on it the color code matched the schematic and the resistance measurements matched.

any way if for some reason I have issues I have enough slack to reconnect per color code (I even left a small tail of the old wire on the socket pin to know which ones were installed different from the code).

there was a single .001 2000v ceramic tube cap off the primary plate side of the tranny to ground, My cap tester only goes to 450v so I could not test for leakage at rated volts. I had a couple .002 3kv disk caps I put in series and used them. I will go ahead and get the proper cap for it.

the plan now is to take it to a local shop with a good tester and check all the tubes out.

checked the vert cent pot, all leads to ground are about 7k which is the same as the B+ load so that looks ok. Thanks for the heads up.

Your welcome, The ctc 16 chassis is a good chassis and will put out a really good picture when you get her working. Here is a picture of my ctc 16 xl.
I really like the cabinet and it has a swivel base. This set had a shorted vert cent pot and it damaged the power supply. I was lucky that it did not take out the power transformer but had to replace all the can caps, B + Diodes, Power switch and the circuit breaker. The person I bought the set from HAD to plug it in and turn it on. :nono:
Ed

nice cabinet, I am going to have to make a cabinet for my the old one is still wrapped up, termites are contained (i hope) but the damage is severe.

right now I am leaning toward a simple ply box with veneers and maybe some nice thin med long legs (the kind that screw on, nice if I can find some with a brass lower half). I sure would like to reproduce something nice like yours but my wood working is limited.


what do you think about the color code problem on that one section? ever run into something like that?

TMA96 info
 

Here's what my manual has for the TMA96 - hope it helps with the tuner woes.

Cheers,

I'll try this again.

got it thx, it sitting on the variac all tubes out for a slow reform.

Wow, Ed! That's a nice looking 16!

I had one similar a few years back, but the top of the cabinet was in pretty bad shape due to getting wet for a very long time. It was a remote set. I gave it to Rich since he was tinkering with rebuilding cabinets back then.

seems the caps are fine, full voltage quickly, no heat, so I plugged in all the tubes and will hook up the crt/yoke/convergence bd tonight for a full power up. I will monitor the B+ current still.


will do this all later today, will post the results later.
wish me luck...

since I had the sams resistance tables I started check some, on the vert tube I had an odd reading on of the pins, noticed it was the vert hold, no big its just the position of the pot, move the pot and I get wild swings. check the pot and indeed it must be very dirty, so will clean up the pot before powering it up. I am just a bit paranoid about that vertical circuit :yes:

I would think some spray in all of the pots would be in order.

Those resistance tables are sweet when it comes to tracking down resistors that may be out of spec. There are, many times, readings that may seems off and actually only be due to a setting of one of the controls.

copy that charlie, sprayed and looking good. checked about 1/2 the tubes, so far very good. I did spray the 4 pots up front. I was a bit nervous about getting into the pots on the back. guess I could note the position and spray work them and get back to that starting position.

IT WORKS!!

I am going to have to touch up the linearity and there is a slight convergence problem (are they related) on the bottom, but it is coming along. I snapped a couple shots before even playing with the tint/color, so it looks better than this now.

oh and my B+ current looked good 440ma Sams calls for 460 :banana:

gonna knock back a cool soda pop, grab some grub, and see if I can clean up the linearity a bit. Gonna need some one to talk me thru the convergence, I have the manual but would rather talk about it 1st.

Thanks for the encourgement and help, esp Charlie for letting my yack on forever.

Man I want one of those NBC peacocks on DVD soo bad...

looking forward to watching the Rockford tonight, will have to setup a lawn chair out in the garage :yes:

Been following your progress. I hope to work on mine this winter. Nice job!!

I will have to get some more pics, it is looking a LOT better.

I think I will add a .5 amp in line fuse to the B+ just for that extra bit of safety. I had a neighbor over, he is technically inclined, I think I may have set the hook in him.. He remembers this stuff like I do a kids from the 60's

GREAT! :yippy::banana::grnbounce:banana::yippy:

Yeah, I've spent many hours out in the garage watching TV... and enjoyed it more than in my living room!

I bet your wife will eventually have to come out there and say, "Honey, when are you going to come to bed???" :D