Old Muntz TV for sale Locally to me, Should I pick it up? - Page 10 - Videokarma.org TV - Video

Tube TV · #**136** 10-03-2019, 02:03 PM

Most likely the smoke around the IF can was caused by bad wax paper cap that's drawing excessive current. All of those wax paper caps are leaking and it they are leaking enough they will smoke, or cook something in the circuit they are connected to.
My own guess is the choke is fine, but if you are putting in a parts order it might be nice to have a spare on hand. I would be looking ahead of the the choke.

What did the smoke smell like? Burnt wax, hot bakelite ?

vortalexfan · #**137** 10-03-2019, 02:11 PM

Quote:

Originally Posted by Kevin Kuehn

Not necessarily, a short to ground in the choke would not cause a component down stream from it to smoke. You could have a paper power supply bypass cap that's leaky or shorted, which generally will smoke a resistor feeding voltage to that circuit. In some cases it could be a coil. Can you post a picture showing the area the smoke came from?

See Picture below for where the magic smoke came from.

vortalexfan · #**138** 10-03-2019, 02:30 PM

Quote:

Originally Posted by Tube TV

Most likely the smoke around the IF can was caused by bad wax paper cap that's drawing excessive current. All of those wax paper caps are leaking and it they are leaking enough they will smoke, or cook something in the circuit they are connected to.
My own guess is the choke is fine, but if you are putting in a parts order it might be nice to have a spare on hand. I would be looking ahead of the the choke.

What did the smoke smell like? Burnt wax, hot bakelite ?

The weird thing is that when whatever smoked smoked it didn't have any sort of burnt smell or any other smell for that matter, it was odorless.

There are some paper caps tied into the power supply on the AC side both of which are tied to ground on one end. Could those be the cause of the issues I'm having?

Tube TV · #**139** 10-03-2019, 02:49 PM

Could have been releasing steam more than smoke.
I doubt than one of those wax paper caps are good. And those electrolytics on the bottom right are probably leaking as well.
It would be better in a lot of ways to change all those caps as they are going to need to be done if you want any kind of reliabilty out of the tv, and furthermore they are likely to send you on a wild goose chase dignosing the probems.
I've had many sets that run ok with the old caps in place for the first 5 or 10 minutes and then everything starts to fail , the vertical starts to shrink, or the high voltage and horizontal drops or completely quits working. It's easier to change all of these and you have a fresh start and you have the caps out of the way of potential problems.
Plus it can simplify diagnosing a set because you won't have multiple issues caused by bad capacitors. This is especially important when you are new to tv's.
The last thing you want is to cook a transformer or a IF can or the flyback, as these can be the hardest parts to get ahold of .

Kevin Kuehn · #**140** 10-03-2019, 03:20 PM

Agree all the paper and electrolytic caps need to be replaced. Take a look at R50, it's suppose to be 1k ohm and feeds B+ to the 1st sound IF stage. C49 (.02uf)is the stages decoupling. Good chance C49 is leaking current to ground and overheated R50.

Kevin Kuehn · #**141** 10-03-2019, 04:34 PM

Quote:

Originally Posted by vortalexfan

There are some paper caps tied into the power supply on the AC side both of which are tied to ground on one end. Could those be the cause of the issues I'm having?

Not the cause of your problems. But they are subject to blowing up if not replaced with some specified for across the AC line or line to neutral, such as these. https://www.mouser.com/ProductDetail...5SnxDEDw%3D%3D

vortalexfan · #**142** 10-03-2019, 04:36 PM

Quote:

Originally Posted by Kevin Kuehn

Agree all the paper and electrolytic caps need to be replaced. Take a look at R50, it's suppose to be 1k ohm and feeds B+ to the 1st sound IF stage. C49 (.02uf)is the stages decoupling. Good chance C49 is leaking current to ground and overheated R50.

I would like to replace all those capacitors at once but I just recently bought a new (to me) car and I now have car payments and I was just dropped down to 2 days a week at work so now my paychecks are going to be a little bit smaller than they have been.
So I'm going to have to hold off on ordering the capacitors for right now (until I have made my first car payment and my other expenses come out which will probably only leave me with about $30 left which won't be enough to get the 20+ capacitors I need to recap this TV).
Unless someone here has some spare capacitors they could send me.

I will definitely check C49 and R50.

vortalexfan · #**143** 10-03-2019, 05:51 PM

Ok, so a little update, I replaced the resistor and capacitor you guys mentioned were probably responsible for the smoke earlier and also a couple other capacitors nearby that I had on hand and I managed to get the tube to stop arcing and the current draw down to 3 amps from the previous 8 amps that it was drawing before.

So I think we're making some progress.

Tube TV · #**144** 10-03-2019, 06:08 PM

3 amps is still pretty high but much better than 8. That's for sure.

Kevin Kuehn · #**145** 10-03-2019, 07:18 PM

Quote:

Originally Posted by vortalexfan

So I think we're making some progress.

Just out of curiosity, how many DC volts do you measure from pin 2 of the 5U4 to ground? And from pin 5 of the 6W4 to ground? Before measuring take a look at the voltage chart(page 8) in your Sams so you have an idea of what to expect.

vortalexfan · #**146** 10-03-2019, 11:00 PM

Quote:

Originally Posted by Kevin Kuehn

Just out of curiosity, how many DC volts do you measure from pin 2 of the 5U4 to ground? And from pin 5 of the 6W4 to ground? Before measuring take a look at the voltage chart(page 8) in your Sams so you have an idea of what to expect.

I'm assuming the set will be powered up for this procedure?
Also will the tubes be removed for this or are they still in the sockets?

vortalexfan · #**147** 10-03-2019, 11:02 PM

Quote:

Originally Posted by Tube TV

3 amps is still pretty high but much better than 8. That's for sure.

Also I did figure out why the fuse wasn't blowing from the excessive current draw, somone at some point in time replaced the original 5 amp fuse with a 10 amp automotive fuse...

Kevin Kuehn · #**148** 10-04-2019, 12:16 AM

Quote:

Originally Posted by vortalexfan

I'm assuming the set will be powered up for this procedure?
Also will the tubes be removed for this or are they still in the sockets?

Yes powered on with tubes in sockets.

Tube TV · #**149** 10-04-2019, 10:57 AM

Quote:

Originally Posted by vortalexfan

Also I did figure out why the fuse wasn't blowing from the excessive current draw, somone at some point in time replaced the original 5 amp fuse with a 10 amp automotive fuse...

Would almost make me wonder if there was some issue years ago that was causing the fuse to blow and that's why they quit using it.
Mind you it could have been replaced more recently by someone plugging it in to see if it worked so that they could as more for it on ebay.....

vortalexfan · #**150** 10-04-2019, 12:55 PM

Quote:

Originally Posted by Kevin Kuehn

Yes powered on with tubes in sockets.

OK well a little problem, when I was replacing some of the capacitors I replaced a couple of .05 MFD capacitors with what I thought were some .047 MFD capacitors but then when I looked at the code on it again I realized it said 472 rather than 473 on it so right now I really can't power on the TV because of it having the wrong value of capacitors in a couple of spots.

I do have a list of the capacitors I need though drawn up, including the electrolytics I didn't replace yet, and interestingly enough this TV uses all of the basic capacitor values like .1, .01, .047, .0047, and .033 (which actually the last one is .035 but .033 will work fine I in its place I think).