My TV Restoration Thread!.

[OS X]

Hi, I decided to start this thread as I have around 70 TV's I'm going to be restoring over the course of years, most of them are B&W Sets, I figured I will make this a all in one thread for all the B&W sets I have. I will apologize in advance if I ask stupid questions, but I'm still learning so there's still a lot of things I don't know, however I got changing Caps down pretty good so far.

We will first start with the 23in Zenith that is on the bench, when I first got this set it would immediately trip it's circuit breaker, I did some research and it looked like it was more than likely one of the electrolytic's so I just replaced them all, that brought the set back to life! It works reasonably well but after it's been running for around 5 minutes the horizontal starts to shrink, I tested all the tubes and all were good I even replaced the horizontal output tube just to be safe, but still no change so I got a few suggestions and it looks like it may be a resistor changing value when the set heats up, I pulled the chassis and measured the resistance of the resistors on the horizontal output tube socket, from what I can find out one resistor was supposed to be a 68k with a tolerance of 10%, but according to my multi-meter if I'm testing it right? It only reads 30K which would be out of spec. I haven't really tested to many resistors before so I may also be doing it wrong. I think I'll just replace that resistor and see if that helps and then go from there

[OS X]

More pictures!

[Adam]

70 sets, and you're getting 2 more Zenith B&W consoles from me later next month! You do get faster at it the more you sets you fix.

When testing resistors, it often happens that the ends of the resistor are connected through some other path in the circuit, and you get a lower reading than you should. You can sometimes look at the schematic and work out what that should be, but often it's just easier to remove one end of the resistor from the circuit and then test it that way.

But if the set works normally before it warms up and the problem is caused by a bad resistor, it won't test that bad when it's cold.

[OS X]

Originally Posted by Adam

70 sets, and you're getting 2 more Zenith B&W consoles from me later next month! You do get faster at it the more you sets you fix.

When testing resistors, it often happens that the ends of the resistor are connected through some other path in the circuit, and you get a lower reading than you should. You can sometimes look at the schematic and work out what that should be, but often it's just easier to remove one end of the resistor from the circuit and then test it that way.

But if the set works normally before it warms up and the problem is caused by a bad resistor, it won't test that bad when it's cold.

Thanks for the tip! Just tried that and the resistors do check in spec so time to replace some more caps, I just did anoter 4 now also do you know what voltage the disc caps would be? It says the value on the one but not the voltage, I figured I'll replace those being there directly connected to the horizontal section, I also measured the high-voltage with the HV Probe on my sencore tester, according to the setup booklet for the CRT it has (23EYP4) it is supposed to be running at 25Kv but it's only reading around 19kv but I somewhat thought 25 KV seems a little high for a B&W set?, Also I'm not sure if we're still making the trip down there next month or not, if worse comes to worse are you going to the September ETF? If so maybe you could bring them there and I could bring the RCA sportabout for you there as well.

[tom.j.fla]

For disc caps that are not voltage marked they are rated at 500 volts D.C. 19 kv is right for a 23 inch B & W crt, 25 kv is max voltage rating for the tube. At max rating tube might be emitting x-rays. All the best, Tom

[Adam]

Originally Posted by OS X

Also I'm not sure if we're still making the trip down there next month or not, if worse comes to worse are you going to the September ETF? If so maybe you could bring them there and I could bring the RCA sportabout for you there as well.

I'd like to but I can't be absolutely certain if I can make it now. But if I can't I could probably still meet you on your way down like before.

Those ceramic disc caps rarely go bad. I think you were probably right before about it being a resistor. They test fine, but then they heat up when you run the set and then the resistance goes up.

[DavGoodlin]

Surprising a rock-solid Zenith BW has a problem (even needing new caps?) but I'll look this symptom up in my Tab Book for Zenith Monochrome to see if I can speed things up 4U.

Get some freeze spray and hit those suspected parts - just don't be tempted to use it on yourself with this heat!

[Bill R]

I wouldn't worry to much about the disc caps. They rarely fail. Change the electrolytics, and the paper caps first.