Repairing Vintage TV's - Comments Invited

[jonboy55]

I've only been a member on Audio Karma for a short time but have been repairing vintage TV's for about 20 years.

Many times I have seen postings from people who when repairing and/or restoring a TV will replace every cap and then see what happens.

This is not the method I prefer and would like to hear from others on their procedures when working on TV's.

When starting on a TV I look to see if there is anything that is burned up or looks like it's going to be a big problem that will keep me from going any further. A destroyed power transformer is an example. I also check the CRT. After that, my first and only priority is to get the high voltage working. With out the high voltage working there is no reason to go any further. I see no reason to recap areas like the audio circuit, tuner, etc. until there is high voltage present.

This saves me time and money especially if I have to find a major HV part like a flyback, etc.

Any comments?

[radotvguy]

I definitly check the crt first . I did on the rca i am currently working on before i recapped it . I also take a good look over to see if there any burnt up components and also check to see if someone was in the set before me and made the set a bit hairy . As far as recapping well if its like a late 40s set or early 50s set then i usually like recapping the whole set . (wax, bumble bee, elemencos, electrolytics ) but on late 50s or 60s stuff that might not have to be done . At least thats my way of thinking

[M3-SRT8]

Yeah, I'll check for any obvious catastrophic failure, check the CRT, etc.

I'll then pull the 5U4's, plug it in and see if the Tubes light. Then, at least, I know the transformer is ok.

I work only on very early TV Sets, made before 1950. Back then, they habitually checked Tubes first, because the likelyhood of a failed tube was greater than a Cap or a resistor. Now, it's exactly the opposite. I replace ALL Electrolytics first, with values at or above spec. Then, I replace ALL Tubulars and ALL Micas. Then, I check ALL Resistors with values above 500k, and all Wire Wounds and Controls. Then, I check the Tubes. Anything suspect, or out of spec, goes.

Then, I do Resistance Checks through the Pins.

THEN, I power it up and check pin voltages, etc.

When you do all this, it greatly cuts down on surprises later. It also greatly increases reliability, and greatly reduces the probability of catastrophic failure, because with the Electrolytics new, and the Ballast operating, anything marginal WILL fail, sooner or later. THAT would increase the probability of taking out something made of Unobtainium, like a Flyback.

LJB

[jeyurkon]

I was repairing TV's for friends before they were vintage. I've only been a member for a short while and I have just started to repair my first set that is now old enough to be considered vintage.

Every electrolytic that I've removed so far has, except for one bad one, tested better than the replacements I bought in terms of capacitance and ESR. The leakage is just a bit higher than the new ones. Every paper capacitor has a leakage of 300ua or more and keeps climbing. I consider that bad.

I may leave some of the electrolytics in. I have some equipment with electrolytics that are older than 60 years and still work well. I'll get yelled at for that, but I will make sure they aren't in a position to damage irreplaceable parts.

I will replace every paper capacitor first. I read a Japanese paper on the failure modes of paper capacitors and even if 300 ua is acceptable it seems that the current is creating some rather nasty byproducts that will eventually destroy the caps.

I've found a bad resistor, it doesn't surprise me since the lead had shorted against the chassis. I won't check the others until I power it up unless they look bad or had a bad cap attached.

I expect to learn from this project. Maybe the hard way.

John

[bgadow]

One of the first things I do with a new find, even if I'm not going to restore it for a long time, is check the crt. When I first starting getting serious about bringing old tv sets back to life I just concentrated on caps in errant circuits. Soon I decided it was easier to just shotgun the paper caps. I generally will give electrolytics a pass back to the mid-50s; older than that, I just change them.

[kx250rider]

My opinions have changed over the years. I started working on 1940s TVs in the late 70s & early 80s... At that time, they were only 30 years old, and many times I could just troubleshoot & repair successfully. But along toward the 90s, it started to become clear that trying to do that is futile. Repair one problem in the horizontal, and next you lose video and get a hum bar, etc etc. So now, I just do a physical look-over (for botch work, condition of CRT, missing parts, burnt parts, etc). At that point, I MIGHT try to Variac the set and monitor the B+, and see what happens. But I will not troubleshoot and repair a set. I will recap the entire chassis, and only then troubleshoot and repair whatever the remaining problems are. With great resources like AK, there's no reason to fear doing a full re-cap and discovering you need an IF can, or a flyback. With a little patience, you can get all that stuff.

The only, AND I MEAN ONLY exception would be if the vintage TV has been in somewhat regular use all this time. Then, I might think about a straight repair.

Charles

[damen]

I always check the crt and for burnt parts and if the crt does not come up after a long cook I will rejuvenate it and if it takes and I realy like the set I will proceed . If i see burnt parts I check for avalibility of parts and then i use a variac to soft start. If all looks good I then recap it and hope for the best.

[peverett]

One thing that I do, at least on sets with heavy chassis, is play the restored chassis quite a while before placing it back in the case. This way, if something fails early, the headache of re-removing it from the case is not there.