On Fri, Jan 22, 2021 at 02:40 PM, Ozan wrote:
Interleaved
Base of Q770 reads +6.090 VDC, while the base of Q780 reads +6.081 VDC
However, the cathode of VR764 reads high a +5.135 VDC....
Ok
VR764 zener is spec¡¯ed at 12.6V +/-5%, with its variation +5.135V at cathode
of VR764 is not out of range. Beam find diodes are still reverse biased with
some margin. You may want to double check cathode of CR764 (beam find) is at
-8.6V, and top of R764 is +8.6V.
Will do.
I recommend looking at the voltages around U760. Its supplies +5V (pin 15) and
-5V (pin 4) are generated locally, that should be the first place. Voltages at
pins 1,2,5,7,8 can give clues about whether operating point of U760 is good.
Pin 3 & 6 voltages not marked in schematic but looking at inside of U760 they
should be about pin 14 voltage minus 0.7V (probably -0.7 to +0.3V).
Here are the voltages I found (before I killed the scope for good).
Pins:
1. -3.17V
2. -0.67V
5. -3.15V
7. +8.54V
8. 0.00V
Ozan
While I was probing pin 5, the display changed to this:
/g/TekScopes/photo/259498/1?p=Created,,,20,2,0,0
/g/TekScopes/photo/259498/0?p=Created,,,20,2,0,0
I just killed the scope for good. Grrr...
I¡¯m quite sure I was very careful, and didn¡¯t touch anything... ?
