Quote:
Originally Posted by zeno
This one is a little different. Usually the neg of that cap goes to GND.
Look off the negative, it goes to the #1 130 V source. There is usually another cap to GND from the 150.. Probably on the PS part of the schematic.
HINT on most Sams there is chart showing how many points a source goes to
This is very handy at times when you are unloading things. 
Anyhows the value of cap I have seen is 4.7 OR 10 MFD. I have seen a few
open coupling caps in the video chain on these sets.
To wrap it up can you post a pix of the symptom ?
73 Zeno 
LFOD ! |
Thanks for the guidance Zeno. I'll look into the PS. Here are two shots of the raster and one bit of the H yoke on the Pincushion section.
The PLUGE shot shows that the right side is brighter. You can see that the right side white bar is visible, but the left side is not. I took this shot because it's too hard to capture the edge glow on the right side with my phone camera. I tried everything I could to make it go away, but none of the geometry controls or puritycontrols change the brightness imbalance. Pivoting the yoke doesn't matter either. The purity is good in my opinion. I degaussed with a good ring as well.
The other shot shows another symptom; the geometry is messed up towards the top. It becomes noticeably wide on the top side of the image, and then pinches back in again at the very top. The pincushion control only does barrel correction, but this is keystone distortion. It also appears that the pivot point for the EW is too high up, or there is some linearity problem. I drew a Red line where it appears that the pivot point is. I mention this because it appears that the geometry control is directly coupled to the H Sweep if I read the circuit correctly. Seems like the H Yoke goes between the CONV OUTPUT transistor and the Pincushion pot, and then to the base of PINMOD transistor.
Also of note is that the Pincushion barrel correction seems to be towards the end of its travel; the picture is biased towards pucking in on the sides. The barrel correction seems to be pivoting symmetrical in the middle vertically though, unlike the keystone (which seems to be too high).
I took some voltages around the PINMOD transistor, and I see that the voltage on the base and emitter are too high. Almost 115VDC on the base and 114V on the Emitter. Should be 110 and 109. The AC waveform on the base is more or less correct at about 10.6V pkpk.
