Hi Edd
Well I have the results from the voltage measurements, they are as follows:
12AU7 Video Amp
Pin 1- 152.7 Vdc
Pin3- .153 Vdc
Pin6- 362 Vdc
Pin8- 8.67 Vdc
Does this give you any ideas as to what might be going on, as you can see 3 of the voltages arre rather out of the ballpark, the capacitor in question the 40uf on the contrast, I have replaced as per all the other capacitors virtually in the entire chassis, as well as any resistors that were out of tolerance.

:Hi Edd
: Well I have the results from the voltage measurements, they are as follows:
:12AU7 Video Amp
:Pin 1- 152.7 Vdc
:Pin3- .153 Vdc
:Pin6- 362 Vdc
:Pin8- 8.67 Vdc
:Does this give you any ideas as to what might be going on, as you can see 3 of the voltages arre rather out of the ballpark, the capacitor in question the 40uf on the contrast, I have replaced as per all the other capacitors virtually in the entire chassis, as well as any resistors that were out of tolerance.
Also, in adjusting the AGC Delay control the only result was a change in the Audio level, no change in the CRT at all.

::Hi Edd
:: Well I have the results from the voltage measurements, they are as follows:
::12AU7 Video Amp
::Pin 1- 152.7 Vdc
::Pin3- .153 Vdc
::Pin6- 362 Vdc
::Pin8- 8.67 Vdc
::Does this give you any ideas as to what might be going on, as you can see 3 of the voltages arre rather out of the ballpark, the capacitor in question the 40uf on the contrast, I have replaced as per all the other capacitors virtually in the entire chassis, as well as any resistors that were out of tolerance.
:Also, in adjusting the AGC Delay control the only result was a change in the Audio level, no change in the CRT at all.
:Sorry too keep adding too this, but here are a few more things I need to tell you, L10, 12, and 13 all check low Ohmage, indicating they are ok. One other very interesting tidbit, when the TV is first turned on, with the Contrast and Brightness controls both turned all the way down, the CRT illuminates like normal and then fades too black, not sure about this one, just thought I would give you as much info as possible.
Mark

:::Hi Edd
::: Well I have the results from the voltage measurements, they are as follows:
:::12AU7 Video Amp
:::Pin 1- 152.7 Vdc
:::Pin3- .153 Vdc
:::Pin6- 362 Vdc
:::Pin8- 8.67 Vdc
:::Does this give you any ideas as to what might be going on, as you can see 3 of the voltages arre rather out of the ballpark, the capacitor in question the 40uf on the contrast, I have replaced as per all the other capacitors virtually in the entire chassis, as well as any resistors that were out of tolerance.
::Also, in adjusting the AGC Delay control the only result was a change in the Audio level, no change in the CRT at all.
::Sorry too keep adding too this, but here are a few more things I need to tell you, L10, 12, and 13 all check low Ohmage, indicating they are ok. One other very interesting tidbit, when the TV is first turned on, with the Contrast and Brightness controls both turned all the way down, the CRT illuminates like normal and then fades too black, not sure about this one, just thought I would give you as much info as possible.
:Mark
:
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With the second video stage voltages being down on the plate a bit is indicative of a little less than normal drive to its input as well as a proportional diminished level to the first video amp stage also. Another thought came to mind also, and that is a the possibility of that pic tube being weak and gassy. A technique for evaluating that condition would be to set up the TV to get the best and most "contrasty" picture by station selection and the adjustment of the fine tuning , as well as the level setting of the contrast control. On a problematic picture tube, it will have a tendency to make a transition at high brightness levels into a silvery condition, which tends to then overide the contrast available from the pic tube and show a dominance of brightness.If one were to decrease the brightness level there would be a threshold where the silvery appearance diminishes and the contrast comes back into play.Check and see how your tube responds to a brightness sweep downwards.
Also when you say "recap" I certainly hope that was not indicative of a complete sweep through the capacitors in the sets IF stages. About the only caps therein I would have considered was the possibility of leakage in caps C46,C45 andC39.
Another thing to verify would be to interchange /swap your V8 12AU7 and the V9 12AX7 and see if there is any enhancement of the contrast.
Up to this point, if nothing enhances the contrast, I would think that is about time to move on to the injection of AF sig into the video strip stages backward to see if the mentioned strong video lines can be acquired.
73's de Edd
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

::::Hi Edd
:::: Well I have the results from the voltage measurements, they are as follows:
::::12AU7 Video Amp
::::Pin 1- 152.7 Vdc
::::Pin3- .153 Vdc
::::Pin6- 362 Vdc
::::Pin8- 8.67 Vdc
::::Does this give you any ideas as to what might be going on, as you can see 3 of the voltages arre rather out of the ballpark, the capacitor in question the 40uf on the contrast, I have replaced as per all the other capacitors virtually in the entire chassis, as well as any resistors that were out of tolerance.
:::Also, in adjusting the AGC Delay control the only result was a change in the Audio level, no change in the CRT at all.
:::Sorry too keep adding too this, but here are a few more things I need to tell you, L10, 12, and 13 all check low Ohmage, indicating they are ok. One other very interesting tidbit, when the TV is first turned on, with the Contrast and Brightness controls both turned all the way down, the CRT illuminates like normal and then fades too black, not sure about this one, just thought I would give you as much info as possible.
::Mark
::
:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:With the second video stage voltages being down on the plate a bit is indicative of a little less than normal drive to its input as well as a proportional diminished level to the first video amp stage also. Another thought came to mind also, and that is a the possibility of that pic tube being weak and gassy. A technique for evaluating that condition would be to set up the TV to get the best and most "contrasty" picture by station selection and the adjustment of the fine tuning , as well as the level setting of the contrast control. On a problematic picture tube, it will have a tendency to make a transition at high brightness levels into a silvery condition, which tends to then overide the contrast available from the pic tube and show a dominance of brightness.If one were to decrease the brightness level there would be a threshold where the silvery appearance diminishes and the contrast comes back into play.Check and see how your tube responds to a brightness sweep downwards.
:Also when you say "recap" I certainly hope that was not indicative of a complete sweep through the capacitors in the sets IF stages. About the only caps therein I would have considered was the possibility of leakage in caps C46,C45 andC39.
:Another thing to verify would be to interchange /swap your V8 12AU7 and the V9 12AX7 and see if there is any enhancement of the contrast.
:Up to this point, if nothing enhances the contrast, I would think that is about time to move on to the injection of AF sig into the video strip stages backward to see if the mentioned strong video lines can be acquired.
:73's de Edd
:~~~~~~~~~~~~~~~~~~~~

Hi Edd
Well as far as the CRT is concerned it is NOS and I have done a complete check of it with my B&K CRT tester, is is in perfect condition, when you speak of swaping the tubes, do you mean put the 12AT7 in the 12AU7 spot and vise versa?and as far as the injection into the video IF Amp Strip, that is going to take some doing, I do not have any socket adapters for the 4 IF AMP tube Strip, I will attempt this, don't know how thats going to go though, any other thoughts would be very much appreciated, thanks again:)
Mark
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