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

[vortalexfan]

Originally Posted by Kevin Kuehn

I meant they show a 6AK5. For starters just measure the plate pins, that's where we're looking for B+.

I just checked through my tube stash and I did end up finding a 6AG5 tube that tested good yet on my tube tester.

Also checked the voltages from the top without the tubes in and they were spot on to where they should be, on pins 1 and 2 of the 6J6 socket I was getting around 193 volts DC, and pins 5 and 6 of the 6AG5 socket I was getting around 193 Volts DC as well, which I think will drop down to the readings on the voltage chart when the tube is in the socket.

Also I think I might of figured out what's going on, a couple of the center pins on a couple of the 6AU6 sockets broke off on the bottom of the Chassis, one of them is in Video the IF Circuit the other one is the Sound IF 6AU6 socket.

[Kevin Kuehn]

Originally Posted by vortalexfan

Also checked the voltages from the top without the tubes in and they were spot on to where they should be, on pins 1 and 2 of the 6J6 socket I was getting around 193 volts DC, and pins 5 and 6 of the 6AG5 socket I was getting around 193 Volts DC as well, which I think will drop down to the readings on the voltage chart when the tube is in the socket.

I have no idea how you're measuring 193 volts dc now if the those tubes are being fed b+ though R13, which a while ago you said you measured 158.4vdc on the input side and 154.4 on the output.

[vortalexfan]

Originally Posted by Kevin Kuehn

I have no idea how you're measuring 193 volts dc now if the those tubes are being fed b+ though R13, which a while ago you said you measured 158.4vdc on the input side and 154.4 on the output.

Why, am I not supposed to be getting 193 Volts there?

Also I'm finally getting some response out of the tuner, it seems that two of my 6AU6 sockets will need replacing unfortunately, but the good news is that the voltages on the 6AU6 Video IF tubes are spot on to what they are supposed to be, I'm just not getting a good connection between the tube and the socket because of the sockets being faulty, (the center grounding lug is busted off on both of them and the sound IF socket some how popped one of its retaining rivets loose) and so there's no reference to ground with them anymore.

So anyways I'm going to have to see if I can find a couple of phenolic wafer style 7 pin tube sockets to match up with the original sockets and install them in place of the broken/intermittent sockets.

[Kevin Kuehn]

Originally Posted by vortalexfan

Why, am I not supposed to be getting 193 Volts there?

The sams schematic and voltage chart don't show anywhere near that voltage on those pins. Also as I mentioned before, the schematic shows the tuner b+ being fed by R13. If you had 158v on the input side of R13, and 154 on the output. There is no way for that voltage to increase on the load side, because the more current you pull thought that resistor, the lower the voltage will go on the output side.

[vortalexfan]

Originally Posted by Kevin Kuehn

The sams schematic and voltage chart don't show anywhere near that voltage on those pins. Also as I mentioned before, the schematic shows the tuner b+ being fed by R13. If you had 158v on the input side of R13, and 154 on the output. There is no way for that voltage to increase on the load side, because the more current you pull thought that resistor, the lower the voltage will go on the output side.

Maybe I mismeasured something, all i know is that I have a picture from my converter box on the TV now, and the picture is rock solid except for the picture not being centered horizontally and vertically, and no audio still.

[Kevin Kuehn]

Yeah.

[vortalexfan]

Originally Posted by Kevin Kuehn

Yeah.

Another update, I now have rock solid audio, the Audio IF was out of alignment so I fixed that, and now I have perfect audio to go with the rock solid picture.

Now I unfortunately am having issues with my high voltage again where my picture is intermittently going bright and dim, and I have a feeling it has to do with that 1 Meg 1 Watt resistor in line with the High Voltage cap for the Picture tube.

[vortalexfan]

Here's where I'm at now, see picture below. I still can't seem to get the picture to fill out the rest of the screen, as you can see in the picture below the screen for some reason won't fill out the upper right hand side of the screen, and I'm still having problems with the jailbars on the left side of the screen and the top of the screen is all stretched out looking and the bottom part is normal looking.

[Electronic M]

Originally Posted by vortalexfan

Here's where I'm at now, see picture below. I still can't seem to get the picture to fill out the rest of the screen, as you can see in the picture below the screen for some reason won't fill out the upper right hand side of the screen, and I'm still having problems with the jailbars on the left side of the screen and the top of the screen is all stretched out looking and the bottom part is normal looking.

The corner is cut off due to mechanical misadjustment (positioning) of the focus coil....play with it's tilt and your corner will come back.

Vertical not filled and non-linear: put a test pattern (in a pinch end credits with even spacing between lines when viewed on a better set will do) on screen and adjust vertical height and linearity simultaneously (may need to juggle vertical centering too)...If you can't get a full linear vertical sweep check resistors I the vertical.

The left vertical lines are probably horizontal drive lines...try adjusting horizontal drive...If that don't do it your probably going to need to adjust the horizontal osc waveform with an oscilloscope.

[Kevin Kuehn]

Another possibility for neck shadow is not having the yoke all the way forward to the bell of the picture tube. Sometimes slight adjustment of the ion trap will do it too, but don't compromise your brightest screen setting just to eliminate a shadow. You're in the home stretch now.

[vortalexfan]

Originally Posted by Electronic M

The corner is cut off due to mechanical misadjustment (positioning) of the focus coil....play with it's tilt and your corner will come back.

I've monkeyed with the mechanical focus coil adjustments for 4 hours and unfortunately I can't get the corner cut-off to disappear, when I get it to disappear on one corner it just reappears on another corner, and vise-versa.

Vertical not filled and non-linear: put a test pattern (in a pinch end credits with even spacing between lines when viewed on a better set will do) on screen and adjust vertical height and linearity simultaneously (may need to juggle vertical centering too)...If you can't get a full linear vertical sweep check resistors I the vertical.

The vertical I can't seem to get it to fill properly, I either gett a stretched image at the top of the picture and a normal picture at the bottom and or not enough fill at the bottom and too much fill at the top, and this TV doesn't have vertical centering adjustments that I can see of.

The left vertical lines are probably horizontal drive lines...try adjusting horizontal drive...If that don't do it your probably going to need to adjust the horizontal osc waveform with an oscilloscope.

The vertical bars on the left side of the screen were indeed horizontal drive lines, I readjusted the horizontal drive adjustment and the bars went away.

But now I can't get the screen to fill out horizontally, for some reason or another I can't get the horizontal linearity and Horizontal Size adjustments to do anything to the screen as far as resizing it goes.

[vortalexfan]

Originally Posted by Kevin Kuehn

Another possibility for neck shadow is not having the yoke all the way forward to the bell of the picture tube. Sometimes slight adjustment of the ion trap will do it too, but don't compromise your brightest screen setting just to eliminate a shadow. You're in the home stretch now.

I did monkey with the Yoke a little bit and it made very little difference (the picture tube was too far in and the high voltage anode of the picture tube was off to the left rather than facing straight up like it should of been so I had to readjust the yoke and deflection adjustments to get a properly positioned picture, I also had to readjust the ion trap as well.

but none of that made any difference as there is still "shadowing" as you call it going on in the picture tube, no matter how I adjust the Focus Coil or the Yoke.

[Kevin Kuehn]

Can you post a few pictures showing how the yoke and focus coil are positioned relative to the picture tube? A side, rear, and top view would be helpful. Tom mentions tilting the focus coil, but if you have wing nuts that allow forward/reward, as well as up/down, all those movements can affect neck shadow. The electron beam is basically looking down the barrel of the neck, and if it's not bent to center by all combined adjustments before it clears the bell of the tube you'll get a shadow.

[vortalexfan]

Originally Posted by Kevin Kuehn

Can you post a few pictures showing how the yoke and focus coil are positioned relative to the picture tube? A side, rear, and top view would be helpful. Tom mentions tilting the focus coil, but if you have wing nuts that allow forward/reward, as well as up/down, all those movements can affect neck shadow. The electron beam is basically looking down the barrel of the neck, and if it's not bent to center by all combined adjustments before it clears the bell of the tube you'll get a shadow.

Well I was able to get a nice bright full picture but then it went dark and I'm unable to see anything on the screen anymore but I can still hear the sound from the signal source.

Unfortunately I'm afraid that 1 Meg 1 Watt resistor that was in series with the high voltage anode to the picture tube might of finally bit the dust as no amount of adjusting the ion trap is bringing back the picture, and I think the resistor was slowly dying because I started out with a super bright picture and it gradually got dimmer until it finally went completely dark.

[Kevin Kuehn]

Originally Posted by vortalexfan

Well I was able to get a nice bright full picture but then it went dark and I'm unable to see anything on the screen anymore but I can still hear the sound from the signal source.

Unfortunately I'm afraid that 1 Meg 1 Watt resistor that was in series with the high voltage anode to the picture tube might of finally bit the dust as no amount of adjusting the ion trap is bringing back the picture, and I think the resistor was slowly dying because I started out with a super bright picture and it gradually got dimmer until it finally went completely dark.

So you've completely lost high voltage, as in no more sparky?

Easy enough to change that resistor, I suppose?