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

[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]

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.

[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.

[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?!

[vortalexfan]

Originally Posted by Kevin Kuehn

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.

Yes I have tried adjusting the contrast control, but it makes very little difference in the brightness of the Picture tube.

[Kevin Kuehn]

Originally Posted by vortalexfan

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?!

No you can't get the raster to lock unless there's a sync pulse from composite video signal being detected. Right now the horizontal and vertical oscillators are free running. You should have the ability to make the vertical roll up or down, just won't lock in. I'd say the vert oscillator sound is normal because you probably have the volume cranked with no audio signal to detect.

[vortalexfan]

Originally Posted by Kevin Kuehn

No you can't get the raster to lock unless there's a sync pulse from composite video signal being detected. Right now the horizontal and vertical oscillators are free running. You should have the ability to make the vertical roll up or down, just won't lock in. I'd say the vert oscillator sound is normal because you probably have the volume cranked with no audio signal to detect.

Well I hooked a converter box up to the tuner and I'm not anything on the tuner, no audio, no video, nothing, and I'm not even getting any snow on the screen, or white noise from the tuner, when I go through the channels or adjust the fine tuner knob, all I'm getting is the sound of the vertical oscillator through the speaker that's it, no white noise, nothing.

[Kevin Kuehn]

Originally Posted by vortalexfan

Well I hooked a converter box up to the tuner and I'm not anything on the tuner, no audio, no video, nothing, and I'm not even getting any snow on the screen, or white noise from the tuner, when I go through the channels or adjust the fine tuner knob, all I'm getting is the sound of the vertical oscillator through the speaker that's it, no white noise, nothing.

Time for more voltage measurements. Does your tuner match that of the sams folder you've been using, a single 6AG5 and 6J6? If so verify that your DC pin voltages match what Sams call out for V1 and V2, from the voltage chart on page 8.

For anyone following here's the tuner portion of the Sams 101-5 schematic along with the voltage chart.

https://live.staticflickr.com/65535/...38a31f87_b.jpg

https://live.staticflickr.com/65535/...ec92c010_b.jpg

[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.