Old Muntz TV for sale Locally to me, Should I pick it up? - Page 27 - Videokarma.org TV - Video

vortalexfan · #**391** 11-14-2019, 12:48 PM

Quote:

Originally Posted by Kevin Kuehn

One advantage of leaving it in place, is that if the springy dag contact becomes a bad connection you'll still have some filtering. Why not temporarily unhook it to see if it's dragging down your high voltage?

That's what I was thinking of doing, but I'm not sure of how to do that because the lead from the 1B3 tube and the 1 Meg Resistor both attach to the top of that capacitor with solder, and my soldering iron had a hard time melting the solder that was attaching those two leads to that capacitor.

vortalexfan · #**392** 11-14-2019, 09:55 PM

OK so A little update, I think I figured out why the TV's High Voltage Section is Screwy, the Doorknob Capacitor that was installed in the TV was actually a 500pF 10kV capacitor which is what the Meck XL750 used in its High Voltage Section and it was a 10" as opposed to a 12" like XQ-776 was which is what mine is basically which called for a 500pF 15kV Doorknob Capacitor.

So I wonder if the TV having an underrated Doorknob capacitor in it might of been what caused the High Voltage Section to go haywire on this TV...

So now I'm going to try bypassing the doorknob capacitor in this set and just powering the TV straight off of the 1B3GT Tube and let the picture tube do the HV Filtering and see what happens.

Electronic M · #**393** 11-15-2019, 10:35 AM

Quote:

Originally Posted by vortalexfan

OK so A little update, I think I figured out why the TV's High Voltage Section is Screwy, the Doorknob Capacitor that was installed in the TV was actually a 500pF 10kV capacitor which is what the Meck XL750 used in its High Voltage Section and it was a 10" as opposed to a 12" like XQ-776 was which is what mine is basically which called for a 500pF 15kV Doorknob Capacitor.

So I wonder if the TV having an underrated Doorknob capacitor in it might of been what caused the High Voltage Section to go haywire on this TV...

So now I'm going to try bypassing the doorknob capacitor in this set and just powering the TV straight off of the 1B3GT Tube and let the picture tube do the HV Filtering and see what happens.

You mean unhooking the doorknob right?... bypass would imply shorting it which is something I'd urge you not to do.

vortalexfan · #**394** 11-15-2019, 11:34 AM

Quote:

Originally Posted by Electronic M

You mean unhooking the doorknob right?... bypass would imply shorting it which is something I'd urge you not to do.

No, I mean completely removing it from the circuit, because you said yourself that the TV could function without it in circuit.

vortalexfan · #**395** 11-16-2019, 03:10 PM

Well good news, I got the parts in today and I installed the new 1 Meg resistor for the High Voltage anode to the picture tube and here's what I have now picture wise for the TV, see picture below:

As you can see replacing that resistor restored the high voltage back to proper working order again, and the retrace lines disappeared as well.

Both Brightness and Contrast controls are set in the middle, in the picture.

BTW its a dark scene in the video I'm using in this test photo, that's why the screen looks darker than it really is.

Electronic M · #**396** 11-17-2019, 11:26 AM

Sounds like things are going good for you. The picture is not displaying viewing this on my PC...

vortalexfan · #**397** 11-17-2019, 12:20 PM

Quote:

Originally Posted by Electronic M

Sounds like things are going good for you. The picture is not displaying viewing this on my PC...

Try it now.

Electronic M · #**398** 11-17-2019, 12:54 PM

The picture on the screen looks decent...
If the sound and linearity are good (it would also be advisable to check the h output cathode current) and it is stable in operation now may be a good time to declare victory and reassemble.

vortalexfan · #**399** 11-17-2019, 01:43 PM

Quote:

Originally Posted by Electronic M

The picture on the screen looks decent...
If the sound and linearity are good (it would also be advisable to check the h output cathode current) and it is stable in operation now may be a good time to declare victory and reassemble.

I just have to readjust the vertical size and linearity so that the picture fits within the shadowmask that's behind the safety glass inside the cabinet, and I think it will be good.

Someone from church is going to be giving me another old TV to putz around with. It's a blonde colored "portable" tabletop unit. But I have no idea what the brand is or what size the TV is but it should be an interesting repair project.

Kevin Kuehn · #**400** 11-17-2019, 02:54 PM

If you haven't already it might be educational to see an actual test pattern on that set. You can download and burn a DVD from this site.

http://www.mytvtestpatterns.com/

Don't go crazy trying to center the DVD patterns on the screen, because I've noticed they vary depending on the source and how they were produced. Still they are great for checking linearity.

vortalexfan · #**401** 11-17-2019, 04:37 PM

Quote:

Originally Posted by Kevin Kuehn

If you haven't already it might be educational to see an actual test pattern on that set. You can download and burn a DVD from this site.

http://www.mytvtestpatterns.com/

Don't go crazy trying to center the DVD patterns on the screen, because I've noticed they vary depending on the source and how they were produced. Still they are great for checking linearity.

Thanks, downloading right now.

UPDATE: Unfortunately I couldn't get the test pattern DVD to work.

Also I completely lost my perfectly setup screen when I went to put the chassis back into its cabinet because when I readjusted the picture tube position in the chassis it made the picture tube stick out too far for the chassis to fit in the cabinet properly, so I had to readjust the picture tube's position in the chassis so it sat back further than I had it which resulted in me losing my perfect picture adjustments and now I'm having a hard time getting the picture to look right with the new picture tube position.
The adjustments are nearly impossible to do with the chassis in the cabinet but I don't want to fiddle around with taking the chassis back out of the cabinet either because its a pain in the behind to get it out and then back in again because the mount that the vertical output transformer attaches to bends and snags really easy and I've just about broke the mount off a couple of times trying to get the chassis into the cabinet.

Any ideas as to how I can go about readjusting this TV properly without having to remove the chassis out of the cabinet, or an easier way to remove and reinstall the chassis back into the cabinet without damaging it?

init4fun · #**402** 11-17-2019, 07:17 PM

Quote:

Originally Posted by vortalexfan

.....Any ideas as to how I can go about readjusting this TV properly without having to remove the chassis out of the cabinet....

Old TV repairman trick ; set up a mirror in just the right spot that you can see the TV screen from the back of the set . This works when the needed controls are all on the top or back of the chassis . If there are any under the chassis you may still need to end up pulling it , again , ah the joys of vintage TV repair ..

vortalexfan · #**403** 11-17-2019, 07:45 PM

Quote:

Originally Posted by init4fun

Old TV repairman trick ; set up a mirror in just the right spot that you can see the TV screen from the back of the set . This works when the needed controls are all on the top or back of the chassis . If there are any under the chassis you may still need to end up pulling it , again , ah the joys of vintage TV repair ..

thanks, I'll give that a shot, I believe all of the adjustments I need to adjust are on the back of the TV only, none on the bottom of the set as far as I know.

vortalexfan · #**404** 11-17-2019, 11:22 PM

OK so quick question about this TV, is the brightness and contrast controls supposed to affect the focus circuit of the TV?

I'm asking because whenever I adjust the brightness and contrast controls on the TV the screen's focus adjustments go haywire in that the screen's focus centering goes way out of whack like instead of the picture being correctly centered in the picture tube it goes way off to the right hand side of the screen and produces a large shadow on the left hand side of the screen and then the screen goes black until you turn the brightness and contrast controls almost all the way to the bottom to the point that the image is barely visable on the screen, any higher than that then I get scanslines on the screen and too high the screen goes completely black.

any ideas as to why or what would be causing this issue?

Its only been doing this since I relocated the picture tube back to its "original" position in the chassis from where I had it previously where it was providing an excellent picture and just needed its vertical size and linearity readjusted to the appropriate size for the shadow mask behind the safety glass in the cabinet.

vortalexfan · #**405** 11-18-2019, 01:04 AM

OK so a little update, I dug out an old B & K Precision DynaJet 666/606 Tube Tester that a friend of mine gave me and I used that to test some of my tubes in my TV including my 1B3GT tubes.
Apparently the most crustiest nastiest looking 1B3GT tube I had in my tube stash which was a Sylvania 1B3GT tube turned out to be the best 1B3GT Tube I had in my stash and all the other ones (including the one that was in the TV when I got it that was marked "VEE" on it that I thought was actually the best tube of them all) turned out to be bad.
The B & K DynaJet 666/606 Tube tester puts a load on the tubes as if they are in circuit when testing the tubes so you get a real world test result as to whether or not the tube is actually good or not so the test results are more accurate.

The interesting thing is that the B & K Tube tester tested the crusty looking 1B3 tube as being almost NOS in the Quality Test and the Grid Emissions test showed no Deflection at all, and the other 3 tubes that my Sencore tube tester tested as "good" the B & K tester tested them as bad including the 1B3 tube that was marked "VEE" on the base (which the Sencore tester tested it as almost NOS).

So it seems I may have found my new go to tube tester...

Also when I put the Sylvania 1B3 tube into the TV the screen's brightness and contrast improved greatly and is now even brighter than it was previously and the weird focus issues that were going on with the contrast and brightness controls being rotated cleared up significantly as well.

I still need to adjust the vertical and horizontal size and linearity yet but I think Its definitely an improvement over what it was previously.

See picture below for what the picture looks like now with the good 1B3 tube in it.