Old Muntz TV for sale Locally to me, Should I pick it up?

[vortalexfan]

Originally Posted by Kevin Kuehn

I should have told you to also measure the voltage which goes to pin 2 of the CRT socket referenced to chassis ground, should be 1.3vdc. You can get to that under the chassis on the end R35 that should be connected to another wire going up to pin 2 of the CRT socket. Use the resistor identification on page 17 of your sams to find the actual physical location of the resistors.

OK, Pin 2 of the CRT is about 1.6 VDC which is only .3 volts higher than the reading given in the Sam's Voltage Chart, so I would say those 3 voltages are in the ballpark of where they should be.

So now how do I go about adjusting the Ion Trap on this TV?

[Kevin Kuehn]

Originally Posted by vortalexfan

So now how do I go about adjusting the Ion Trap on this TV?

Basically you rotate the ion trap magnet, at the same time sliding it back and forth until a raster appears on the screen. For starters turn the brightness up full and dimming the lights will help you catch the location. Once you get a raster you turn the brightness down and fine tune the traps location for brightest raster. Don't panic if you don't find the location right away.

[Edit] If you find two locations that are brightest along the length of neck, you want the one closest to the base of the the tube.

[vortalexfan]

Originally Posted by Kevin Kuehn

Basically you rotate the ion trap magnet, at the same time sliding it back and forth until a raster appears on the screen. For starters turn the brightness up full and dimming the lights will help you catch the location. Once you get a raster you turn the brightness down and fine tune the traps location for brightest raster. Don't panic if you don't find the location right away.

There's a little bit of a problem, the ion trap doesn't move very easily, in fact it moves so hard that it feels like I might neck the tube if I move it too much...

[Kevin Kuehn]

Originally Posted by vortalexfan

There's a little bit of a problem, the ion trap doesn't move very easily, in fact it moves so hard that it feels like I might neck the tube if I move it too much...

Do you see any tensioning device on the trap like a thumb screw, or is it just a spring tension? It might be helpful if you can post a picture of what the beast looks like. You absolutely don't want to get forceful with it.

[vortalexfan]

Originally Posted by Kevin Kuehn

Do you see any tensioning device on the trap like a thumb screw, or is it just a spring tension? It might be helpful if you can post a picture of what the beast looks like. You absolutely don't want to get forceful with it.

Well, one things for sure, the ion trap on my tv looks nothing like the one in the picture on the service manual...

I was able to get a raster, albeit a very dim one, and the only way I could get the raster to appear was with the brightness control set in the middle, if i turn the brightness control all the way up the picture disapears, and if I turn it all the way down the picture disappears as well, it only shows up when the brightness control is set in the middle.


Picture of the TV's raster, and ion trap posted below.

[vortalexfan]

sorry about the crappy quality photos, cellphone's battery was nearly dead.

as you can see the ion trap on the picture tube is just spring tension, and that's it, and its not a very good ion trap.

[Kevin Kuehn]

Originally Posted by vortalexfan

sorry about the crappy quality photos, cellphone's battery was nearly dead.

as you can see the ion trap on the picture tube is just spring tension, and that's it, and its not a very good ion trap.

Agree. I may be able to scare up a better one with the two thumb screws. Just a thought... have you tried adjusting the contrast control, because if there is no or little signal coming through from the front end, the DC restoration may be biasing the CRT's grid for a very low brightness level. I'm sure someone else will tune in with a better explanation.

[Kevin Kuehn]

Well that's a good starting point. Can those bar magnets be centered in the clamp doohickey so they are the same position on both sides? Not sure how much that will help. I need to sleep on this, not sure off hand why the brightness would need to be in a center position. There's also the possibility that someone has had that trap off the neck and it needs to be reversed front to back. Some traps have an arrow that indicates the end to be pointing forward.

[vortalexfan]

Originally Posted by Kevin Kuehn

There's also the possibility that someone has had that trap off the neck and it needs to be reversed front to back. Some traps have an arrow that indicates the end to be pointing forward.

Yes there is an arrow on this Ion Trap and its facing forward towards the front of the picture tube, also I did adjust the focus adjustment knob and I got a much clearer picture than before.

I also can't seem to get the vertical and horizontal hold to lock in, and is it normal to be able to hear the vertical oscillator through the speaker on the TV?!

[old_coot88]

Originally Posted by vortalexfan

I was able to get a raster, albeit a very dim one, and the only way I could get the raster to appear was with the brightness control set in the middle, if i turn the brightness control all the way up the picture disapears, and if I turn it all the way down the picture disappears as well, it only shows up when the brightness control is set in the middle.

Sounds like the raster is 'blooming' from HV sag. Have you subbed the HV rectifier tube?

[Kevin Kuehn]

Originally Posted by old_coot88

Sounds like the raster is 'blooming' from HV sag. Have you subbed the HV rectifier tube?

I knew you'd have a good idea. Also that 1 meg series resistor that measured good. I always replace those regardless for fear of them breaking down under high voltage.

[vortalexfan]

Originally Posted by old_coot88

Sounds like the raster is 'blooming' from HV sag. Have you subbed the HV rectifier tube?

Yes, I ended up putting the hi volt rectifier that was originally in the set when I got it back into the TV and now I have a nice bright raster on the screen.