Zenith 25EC58 - color problems
 

So last night I sit down to watch some TV on my Zenith around 9PM, thinking how great it is that I finally found a color TV that doesn't need too much in the way of regular repairs. (The last I did was to replace the tripler 4 years ago). And then it just shuts off on it's own, no sound, no picture, no nothing.

First I tried the obvious, power cord not plugged in all the way, circuit breaker... It was none of that. Then I looked at the power supply, diodes, filter caps... It was none of that. But something was shorting the B+ to ground. I finally found the problem around 3AM, after having pulled all the modules out, and disconnected quite a bit of stuff trying to isolate it.

So get this, it was one of those notorious 22-5001 caps. But not like you think. Instead of one of those white ones going open, an orange drop one shorted:saywhat: I replaced them all with the orange drop ones back when I replaced the tripler. I had one extra, so I put in in, and put everything back together.

By this time, it's 4AM, I turn it on... NO COLOR:sigh:

Now if I turn the color killer way down, and the color control way up, and hook it to the color bar generator with the output cranked all the way up, I can get that pattern where the 3 colors are in horizontal lines rolling up and down the screen. On an older color set, this usually means I can adjust the color oscillator frequency and get it to work. But I don't see any such adjustment on this. I'm much more at home working on tube b&w, solid state color I'm not so sure what I'm looking at. I already tried the simple stuff like making sure the modules were plugged in all the way, nothing under the chassis was shorted... I'm not so sure if this was something I caused by removing all those modules and putting them back, or something else went when that capacitor shorted...

I got lucky. I pulled out that 9-27 board again, resoldered the crystal and anything else that looked a little iffy. Also pulled the chip out, and put it back in making sure all the pins were making contact. And that did it.

I'm going to touch up the convergence before I put it all back together. I broke my big mirror last year, and it's so much easier to do with a large mirror. So I'm going to go get one tonight.

Does anyone remember where the degaussing coil plugs in? I forgot, and I'm not seeing it on my schematic.

Not immune to shorting obviously, but at least far less likely to go open, which is what will do the damage if left long enough.

Not sure just how similar the 25DC56 is to the 25EC58, so I don't want to trace the coil wires in my own set to what may be the wrong spot in yours.

I decided to check mine after all, but you'd better double-check what's coming off those pins in the schematic. I've got two red wires on the back of the chassis plugged into a board with two rows of vertically-arranged solder cones, next to the power tranny and a big filter can. They're plugged into the lower-right pins, not including the pin holding the board in place which it probably wouldn't fit anyway.

That's right it is where it goes. And the power supply on the 25EC58 is basically the same as 25DC56 with the voltage regulating transformer, I just looked it up.

I touched up the convergence, and this is better than it's looked in a while.

She looks great.
Other things to watch for with color probs are the
normal-align switch & bad IC sockets. The sockets are less
reliable than the IC's & got eliminated on rebuilts in later
years. Same thing goes for hybrids & uprights.

73 Zeno:smoke:

The socket wasn't one of the things I resoldered, but one of the things I did do when I did the resoldering was to take the IC in and out a few times to make sure it was making contact, so that could have been what fixed my problem.

This picture on set looks so much better than it has in a while, not only was the convergence off, but one of the wires going from the vhf antenna terminals to the vhf tuner had come loose. I forgot how good the picture on this set can look.