RCA CTC-36 Woes

[dieseljeep]

[QUOTE=ctc17;3059430]Is CTC36 that 19inch tube deal with the low focus voltage crt?

Those sets had a great picture on them when they were newer.
After they got a few years old, the focus seemed to be rather poor. Even if the CRT tested good and all three guns equal, the clairity was lacking. I have a CTC51K and a CTC53, same thing. I got used to seeing clear scan lines on a CRT set, but those sets are a disappointment.

[Kamakiri]

I have to say, the focus is pretty darn good on the set. These pics were shot before the "incident", but the picture is pretty much the same now, save a hint of retrace.....

I actually have two of these sets. The other has the "use it one day, it's working, turn it on later, and now the set has no sound or picture but has a full raster" issue that I seem to run into with late 60s RCA color sets. That'll be the next one I tear into.

[andy]

...

[DaveWM]

If it was better before a bad cap, and now you replaced a cap and it is not a good as it was, it would be logical to look and see if any resistors around that cap may have taken a large surge, and perhaps are now way out of spec. I see a diode in the vert blanking circuit, while I doubt its the problem would not hurt to check.

[Kamakiri]

Decided to put a couple more hours on the set tonight, and the result was the same.....light retrace. The picture started out jittery, but stabilized after about 10 minutes of play.

In the automotive field, there's some points in time where you have to allow the component to fail, to identify the root cause. Since my diagnostic skills leave something to be desired (I can spot the easy stuff), I decided to give that a try. Didn't woik .

Since there's only about a half dozen resistors on that board IIRC, I'm just going to go ahead and replace them all. I figure if you're going to take the time to desolder one end to take the resistor out of the circuit, you might as well just do the other end too and replace it......

[Kamakiri]

Meanwhile, I decided to play around with the set's twin brother that I have. It's a newer model, ES415W, which shows to be a CTC-53 chassis, with the 18VDBP22 picture tube. I saw a date inside of 1973 on one of the components, meaning this set must have been one of the last tube sets RCA made. Weird thing is that it's not a Mural set.

Physically, VERY close in appearance to the other set. Makes a nice picture, too....after cleaning dirty pots and just letting it run. Now, I just have to figure out how to adjust the horizontal centering......

My only complaint about these sets is that they take FOREVER to warm up and produce a picture. The sound comes on after about 10 seconds, then it takes so long to see anything on the screen, you'd swear you lost HV

[Kamakiri]

[QUOTE=andy;3059484]

Originally Posted by dieseljeep

Those low focus voltage CRTs can really benefit from a very light rejuvenation, even if they test good. I've found the "cleaning" mode on my Beltron brings back razor sharp focus without being too harsh on the CRT.

I did exactly this yesterday, because the CRT seemed pretty dim. The CRT tested bad, bringing up the heater voltage to 8.8 and letting it cook for 10 minutes yielded a marginal improvement. Since it still has a watchable picture, though not really bright, I really hesitate to do a rejuvenate.....