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

[vortalexfan]

Originally Posted by Electronic M

Yeah.... unless you have a TV sweep/marker generator and an oscilloscope and a bit of practice on a set you don't care about you should NEVER touch video IF adjustments in a TV.... Advice I've give everyone who mentions wanting to adjust IF.

Audio isn't hard to fudge a proper adjustment by ear, but video isn't something anyone is likely to get right without instruments.

Well unfortunately the video IF was already screwed up on this thing before I even touched it, as all three Video IF Coils adjustments were backed out to the point that they were almost completely out of their cores, so my fiddling with it really didn't make it much worse than it already was.

So unfortunately this TV (unless someone can loan me the right tools to do it right) may just never work correctly like it did when it was brand new.

[Kevin Kuehn]

I think what you're dealing with is a CRT that's seen it's better days. I don't see that this set has any vertical retrace blanking circuitry, so pushing the brightness up will only irritate the retrace line issue. The channels being off can only be corrected in the tuner, not the video IF. The whole Video IF can be shifted slightly and it would only affect the picture and sound response, it's in no way capable of moving individual channels to new locations. Are you 100 percent sure your home brew dial indicator has the channels in the correct locations? Some tuners have an individual oscillator slug for each channel, however Sams 101-5 mentions bending the coils to align this TV's tuner channels. I really would not recommend you go there without having the proper equipment.

[vortalexfan]

Originally Posted by Kevin Kuehn

I think what you're dealing with is a CRT that's seen it's better days. I don't see that this set has any vertical retrace blanking circuitry, so pushing the brightness up will only irritate the retrace line issue. The channels being off can only be corrected in the tuner, not the video IF. The whole Video IF can be shifted slightly and it would only affect the picture and sound response, it's in no way capable of moving individual channels to new locations. Are you 100 percent sure your home brew dial indicator has the channels in the correct locations?

Well I don't think there's anything wrong with the picture tube because I have managed to get a nice bright picture out of it before that didn't have retrace lines in it (just look at some of my previous posts).

As for the tuner escutcheon goes, all I had to go by was a very poorly shot picture of a tv just like mine that someone on here had picked up a few years back and posted about on here, and from what I was able to make out in the picture, the position of the numbers on my dial are just like on the original.

[Kevin Kuehn]

I can tell from your last picture that the video frequency response is not that terrible, which indicates the IF alignment isn't too far out. There could possibly be something messing with the overall gain, but I doubt it's alignment. Since you've already done so I guess you can justify that you've nothing to loose by further fiddling with it. What others are warning of is that there's no proven method to the madness in doing things that way. I suppose if you happen to have a photographic memory you would stand a better chance.

[vortalexfan]

Originally Posted by Kevin Kuehn

I can tell from your last picture that the video frequency response is not that terrible, which indicates the IF alignment isn't too far out. There could possibly be something messing with the overall gain, but I doubt it's alignment. Since you've already done so I guess you can justify that you've nothing to loose by further fiddling with it. What others are warning of is that there's no proven method to the madness in doing things that way. I suppose if you happen to have a photographic memory you would stand a better chance.

Well actually I am very good at remembering things especially if it's useless information (such as the year a classical composer was born and when they died, electronic and computer repair information, etc.)

Anyways I do know that when I got this TV all three of the Video IF adjustment coil slugs were backed out pretty far which tells me that there was video problems with this TV previously and someone tried to fix it by turning those IF adjustments and apparently it didn't fix it so that was why the TV was taken out of service.

And I'm going to try and see if I can adjust the tuner. If it doesn't adjust to where the position should be on the tuner dial bezel, then I'm going to say that the bezel is incorrect.

[old_coot88]

Well since the ship's already sailed, no choice now but to forge ahead.

A few years ago on here there was a lengthly thread by a Noobie who restored his grandparents' heirloom DuMont. Turns out the Grandad had screwed with all the video IFs, and the grandson, without any instrumentation at all, eyeball-aligned it back into showing a near-perfect picture. Just took enough time, determination and patience. Germane part of the resto saga begins with post # 101 --

http://www.videokarma.org/showthread...ignment&page=7

[Kevin Kuehn]

One thought if you're insistent on adjusting the IF coils, is that the Video IF response is not peaked to one frequency like an AM radio, there is a specific band pass response curve which is shown in the Sams alignment instructions. If your memory is good study that curve and the corresponding frequencies associated with each coil before you just go willy nilly cortwerkulating on things.