Old Muntz TV for sale Locally to me, Should I pick it up? - Page 9 - Videokarma.org TV - Video

vortalexfan · #**121** 10-03-2019, 12:46 PM

I looked over at Antique Electronic Supply (AES) and it seems they actually have the Filter Choke I need for the Power Supply on the TV.

The Specs given in the Sam's Folder is 1.5 Henries .200 ADC, which I'm assuming .200 A is the same as 200mA which if that's the case AES has a version of that particular Filter Choke in stock and its only $15, the only difference is that the ones AES has are rated at 56 Ohms rather than 32 Ohms like the original which I would think that wouldn't matter too much.

vortalexfan · #**122** 10-03-2019, 12:49 PM

Quote:

Originally Posted by Tube TV

Also wiggle the wires on L1 while rechecking for the short to ground to rule out a possible intermitent short . To be at infinity on one side of the choke is not possible.
The choke is simply one long run of wire on a transformer core.

Its checking infinite on both wire leads, not just one of them, I rechecked my work.

Kevin Kuehn · #**123** 10-03-2019, 12:59 PM

Quote:

Originally Posted by vortalexfan

Its checking infinite on both wire leads, not just one of them, I rechecked my work.

A Hammond #156R should do the trick. As far as intermittent resistance to ground, it's very possible the insulation is breaking down under presence of high voltage, then acting flaky without. If it were my set I'd probably be temporarily tacking in a large wattage 50 ohm resistor to replace the choke and continue to trouble shoot. Ideally you should be bringing up the AC voltage slowly with a variac, or at minimum a dim bulb tester while monitoring the power supply voltage. Highly unlikely your out of the woods, but it's a great start!

Tube TV · #**124** 10-03-2019, 01:04 PM

If if consistantly reading infinity, and 27 ohm between the leads it's fine. And the reading on the LCR meter are in spec. If it was shorted the LCR reading would be way off . So I'd say that you've ruled it out as a potential problem.

Tube TV · #**125** 10-03-2019, 01:07 PM

Yes, what Kevin said is dead on. There could be a insulation breakdown that shows up with the higer voltages.

vortalexfan · #**126** 10-03-2019, 01:10 PM

Quote:

Originally Posted by Kevin Kuehn

A Hammond #156R should do the trick. As far as intermittent resistance to ground, it's very possible the insulation is breaking down under presence of high voltage, then acting flaky without. If it were my set I'd probably be temporarily tacking in a large wattage 50 ohm resistor to replace the choke and continue to trouble shoot. Ideally you should be bringing up the AC voltage slowly with a variac, or at minimum a dim bulb tester while monitoring the power supply voltage. Highly unlikely your out of the woods, but it's a great start!

I actually do have a variac but its currently not wired up, as it needs a box or something to be installed in and then an outlet wired up to it and a cord as well. (it was a variac that was inside a console style cabinet originally as part of a speed control on a milling machine of some sort).

Kevin Kuehn · #**127** 10-03-2019, 01:13 PM

Quote:

Originally Posted by Tube TV

If if consistantly reading infinity, and 27 ohm between the leads it's fine. And the reading on the LCR meter are in spec. If it was shorted the LCR reading would be way off . So I'd say that you've ruled it out as a potential problem.

A quick way to find out would be to resolder the input lead, but leave the output lead disconnected.

vortalexfan · #**128** 10-03-2019, 01:15 PM

Quote:

Originally Posted by Tube TV

Yes, what Kevin said is dead on. There could be a insulation breakdown that shows up with the higer voltages.

That's what I was thinking as well.
I will more than likely order a new Filter Choke from AES and install that into the TV and see if that doesn't do the trick.

https://www.tubesandmore.com/product...d-open-bracket

So will the Filter Choke in the link above work, the one that's labeled 1.5 Henry and 200 mA?

vortalexfan · #**129** 10-03-2019, 01:16 PM

Quote:

Originally Posted by Kevin Kuehn

A quick way to find out would be to resolder the input lead, but leave the output lead disconnected.

which one is the input lead and which one is the output lead?
I'm assuming the input lead is the one that's connected to the white wire that was coming off pin 2 of the 5U4 tube socket?

Tube TV · #**130** 10-03-2019, 01:21 PM

Quote:

Originally Posted by vortalexfan

which one is the input lead and which one is the output lead?
I'm assuming the input lead is the one that's connected to the white wire that was coming off pin 2 of the 5U4 tube socket?

It will be the one that is connected to the filter cap + lead that is connected to the 5U4.

Edit: yes pin 2

Kevin Kuehn · #**131** 10-03-2019, 01:41 PM

Quote:

Originally Posted by vortalexfan

I'm assuming the input lead is the one that's connected to the white wire that was coming off pin 2 of the 5U4 tube socket?

Yes the white wire that should now be connected to the plus side of C1A.

vortalexfan · #**132** 10-03-2019, 01:44 PM

Quote:

Originally Posted by Tube TV

It will be the one that is connected to the filter cap + lead that is connected to the 5U4.

Edit: yes pin 2

OK so I tried what you said and also swapped out the rectifier tube with a NOS one and the tube didn't arc, so I tried hooking up the second lead and turned on, and the tv the tube still didn't arc but something smoked on the bottom of the TV right around one of the IF cans but what's weird is that none of the parts where it looked like the smoke was coming from looked toasty (unless the IF can itself was cooked), so going by that information it does seem that the Filter Choke is bad.

Kevin Kuehn · #**133** 10-03-2019, 01:44 PM

Quote:

Originally Posted by vortalexfan

So will the Filter Choke in the link above work, the one that's labeled 1.5 Henry and 200 mA?

Their part number P-T156R should be fine. If the mounting spacing is off you may need to drill a new hole.

Kevin Kuehn · #**134** 10-03-2019, 01:50 PM

Quote:

Originally Posted by vortalexfan

so going by that information it does seem that the Filter Choke is bad.

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?

Electronic M · #**135** 10-03-2019, 02:02 PM

Quote:

Originally Posted by vortalexfan

which one is the input lead and which one is the output lead?
I'm assuming the input lead is the one that's connected to the white wire that was coming off pin 2 of the 5U4 tube socket?

Chokes are non-polarized and there is no such thing as connecting it backwards.

Only tubes, diodes, transistors, and electrolytic capacitors are polarized.