NICE RCA CTC-40 combo!! - Page 4 - Videokarma.org TV - Video

AUdubon5425 · #46 07-06-2010, 05:14 AM

Now that, Sir, is a machine!

RCAkid · #47 07-06-2010, 11:18 AM

Quote:

AUdubon5425 Now that, Sir, is a machine!

She is indeed a machine. Still pretty much feel like a kid around it.

Makes me think that RCA was trying their foray into the CM realm. I have only seen pics of the big CM sets but after this grand lady, can't EVEN imagine seeing one of those come into the house. I am fortunate to have a partner who mostly likes em too. My next door neighbor thinks I am nuts and she KNOWS she is glad she isn't my wife. LOL

Here are a couple more pics of the innards and such. The screen shot of the commercial is before resetting the yoke, purity and vertical height.

I was watching it some more last night during the news and the pic was incredible. Quality, with exception of the blacks, rivaled my DLP set. Color was very close. I am debating on whether or not to touch up the crt. The crt delivers a really good picture but one can tell it does have some time on it, probably mainly due to the instant on thing. Don't get me wrong, as you can see from the pics of the chassis, it has been played. But the dust is just dust, not the greasy mess that it seems to get to when really played hard. The crt will lose just a touch of focus when brightend up. The focus pot is all the way to the right and has no more travel. I will be checking the voltages on the crt and the crt itself to get a good idea of just what kind of shape it is really in. But the pic is good enough that I may not do more than cook it a bit. And at 26,500 volts, that chassis packs a whollop.

DaveWM · #48 07-06-2010, 11:23 AM

a regular battleship, very nice looking pics.

becareful cleaning it, old coils and wires do not like to be disturbed.

RCAkid · #49 07-06-2010, 11:36 AM

A very good reminder indeed. But the dust has got to go!

DaveWM · #50 07-06-2010, 12:01 PM

what I have found to work well is a soft makeup brush (ask you lady for a doner) and a vac with the hose, lightly brush around the boards to disturb the dust, and let the vac suck it up.

I like to clean around the anode with a damp cloth to get all the dust and possible arc paths out of there.

looks like it has some serious speakers, that is a plus that it uses them for the tv, not all the console do, I have one that has a little 4*6 speaker for tv, ugh.

RCAkid · #51 07-06-2010, 01:29 PM

That's good advice on the makeup brush. Hadn't thought of that one.

Yes, the speakers do pack a wollop. On my CTC-21 combo the sound goes through the speakers as well but are just powered by the tv chassis itself rather than the stereo amp. It still sounds amazingly good but doesn't compared to the CTC-40 setup.

Have to be careful though....don't want the family tv (the ctc-21) to get too jealous and start frying components in protest

I was looking at it a little while ago and the top of it was reminding me of something and it hit me.....if there was a conn tower, stripes and aircraft on it, it could be an aircraft carrier.

freakaftr8 · #52 07-06-2010, 02:00 PM

That set has a great picture! Makes my really wanna find a donor cabinet for my CTC-40! I too have a focus issue although my focus knob is all the way to the right already, but needs more. Im sure the focus resistor is shot to hell.

RCAkid · #53 07-06-2010, 03:23 PM

Yeah, my focus pot is all the way to the right as well. When the crt brightness is turned up past about 1/2 of its travel, the pic gets a little out of focus. Other than that, the pic is quite clean and still bright, just the blacks are a bit off as the contrast is also turned down....too much contrast, about 1/2 of the travel of the pot or better and the pic starts to wash out.

That is why I figured the crt my be a bit tired.....but the fact that the focus pot is at the end of its travel might indicated that the focus resistor is near the end of its life. Might need to replace that before it becomes more of an issue.

RCAkid · #54 07-06-2010, 03:34 PM

I do have a question....it has been on my mind since I got my g-2000 with the ctc-47 chassis.

Over near the hv section, there is a round commutator coil that is mounted at the back of the chassis just above the focus pot.

What the heck does that thing do? I have not seen it on previous chassis's to the CTC-40 and 47......any ideas on its function?

rca2000 · #55 07-06-2010, 03:38 PM

Keep in mind that set DOES use a tube HV rect!!

And if it gets weak...it COULD cause some de-focusing and such. It is a 3cz3, but I think one can use a 3a3C in its place if needed.

freakaftr8 · #56 07-06-2010, 04:09 PM

Really! You can sub with a 3A3? I didn't know that bi should test mine again. The 3a3c is best for minimum radiation. The a and b series were a bit more prone to radiation. I don't det any wash out with my contrast cranked all the way. I hate to be the bearer of bad news but test that CRT. Could just be something as simple as cooking the heaters at 8v overnight.

andy · #57 07-06-2010, 07:21 PM

...

Findm-Keepm · #58 07-06-2010, 09:17 PM

Quote:

Originally Posted by RCAkid

I do have a question....it has been on my mind since I got my g-2000 with the ctc-47 chassis.

Over near the hv section, there is a round commutator coil that is mounted at the back of the chassis just above the focus pot.

What the heck does that thing do? I have not seen it on previous chassis's to the CTC-40 and 47......any ideas on its function?

When an SCR fires, it stays on....unless commutated (polarity reversed) or disconnected from the power source. It's similar to a latching action. The commutation coil provides a "swing" (similar to flyback action) that reverses the current flow, shutting off the SCRs during retrace. There are several ways to commutate an SCR circuit - the coil (with accompanying capacitor forming an L-C circuit) is just one.

For the REALLY interested, the attached PDF file explains it in Engineering terms. I've got the XL-100 and Trans-Vista factory service clinic literature around here somewhere that puts it in simpler terms.

Cheers,

Findm-Keepm · #59 07-06-2010, 09:33 PM

RCA's patent on the CTC-4(X) SCR deflection circuit - explains some more, specific to Horizontal Deflection.

Cheers,

rca2000 · #60 07-06-2010, 09:55 PM

I am SO glad this set was saved....and did not end in a garbage truck!!

MIND YOU--I would have REALLY liked to be the one showing it off and such. But that was not an option. Thank goodness one of "US" has it now.

And VERY good job--in getting those pictures!!! I have SOOO long wanted to see that RS-246 amp "for real"--and not just in a service manual!! It DOES INDEED look pretty beefy---with that big sink and tranny. Looks like someone has "worked on it" before though--that cap does NOT look original.

And BTW--AFAIK--ALL SCR sets use that commutating coil--it is part of the scr circuit--as was discussed. I think it is in the retrace ckt. IIRC...the "trace" ckt stores energy and drives the yoke--and it is discharged in the "retrace" pulse--into the flyback and thus--HV....or something like that--it has been many years since I read much about the SCR deflection system. I know most techs HATED them--in the old days!! I personally liked the SCR setup.