Power transformer replacement??

[wa2ise]

Originally Posted by Tubejunke

What I did was remove the rectifier. That its self deisconnects 3 leads. Then I removed the two leads going to the small strip with a B+ fuse (I thiink). I removed a lead that goes to one of the filters and I think one that supplies the heater string. I also disconnected the ground side if the line filters. This should have eliminated the short if it were in any of those circuits. I applied AC from the wall and still have a heavy current draw. The transformer hums like it is working its a** off what little time I can leave it on, which is a matter of seconds. The line chord will get hot and there has been a burning smell. I have nearly every indication that the trans is bad.

My next step would be to remove the power transformer from the set (but keep track of what lead went where, especially the primary). Once the transformer is removed, I'd try applying line voltage to the primary briefly again to see if the short is still there. Check the insulation of the wire leads; if it looks brittle and crumbly, the short might be there. Carefully remove the end bell the wire leads come from (if you didn't already do that to remove it from the set) and check further, and slip heat shrink insulation on the problem leads. Of course, if the transformer smells like toast, it might be toast, but don't give up easy on it.

If the transformer in the set is drawing so much current that it makes the line cord get hot, I'd wonder about the circuit breakers or fuses in the house. Check that nobody stuck pennies behind the fuses....

[Bill Cahill]

I totally agree. I also don't see alot of similarity between motors, and transformers. The transformer sounds very shorted, alright, but, I'd agree you should remove it, and physically check the wiring first. If the transformer is making a bad odor, it probably is burned. I'd also suspect something in your house isn't right, as this should trip a breaker, or blow a fuse. The fuse in the tv is only a boost fuse for hv section. You eliminated one possibility by pulling 5U4's. I think this set uses two, but, I could be wrong.

I still say your filters are shot, and reming you there is usually a resistor from line to chassis as well as the grounding capacirots.

By the way, those two line caps were supposed to eliminate line interference, especially from medical devices, which are not even used any more. In most cases, removing them permanently will not affect the performance of the set, and actually, make ths set electrically safer.

Do now, however, attempt this on a ac dc set with out a transformer, as they are a different animal all together.

If the tube line up is the same as yours, chances are a replacement transformer would be fine. Make sure of every wire on both new, and old one. Colors don't always match.

By the way, it might be safer to put a light in series with the primary of the transformer. Under normal circumstances, you'd need a fairly high wattage, but, for this kind of shorts test, 60-100 watt should be plenty. If butl light full blast, no doubt about it, you have a major short. You obviously do, anyway, just, where is it?
It is a fairly common set, so shouldn't be hard to find the correct transformer for. But, consider this.
What is the physical condition of your set?
What type of cabinet does it have?
Are you really in love with the set?
Are you willing to put what ever it takes into bringing the set back to life?

By the way, there is still the resistor network going from B- to the chassis, and will still show a "short".

In all fairness, I love the old sets myself, but, don't destroy a better one for what you have.. It's a nice set, but, RCA used this chassis in many models. By the way, what is the exact chassis no? It would have a KCS in front of it.

KCS stands for Kinescope chassis set.
If anyone is wondering, The CT in RCA's color line stands for Color Television.

Bill Cahill