On Tue, Dec 28, 2021 at 08:12 AM, Joe wrote:
I have a Tek 465B that had a graticule bulb burn out. I replaced the bulbs,
but must have sparked the board to the chassis when replacing it as I have no
voltage at the output now.
I¡¯m currently looking through the manual now, but if anyone has any input
I¡¯d greatly appreciate it!
Refer to Schematic #12 POWER SUPPLY. The entire circuit is laid out there and this will help guide you. NOTE: I am referencing Manual # 070-2757-00. Other manuals may be slightly different
Confirm no voltage change at the pins for P4086 on the A4 board when rotating the scale illumination control. Of course, check the lamps to make sure they are still good Check F4507 for an open condition. If F4507 is not open, check + terminal of C4531 for About 9V. Check +5V (Unreg) and +15V LV supplies for correct voltage at the various test points and circuit components. You need a minimum of +5V (Unreg) and +15V for scale illumination to work.
IF your LV is in good order, then check the individual Scale illumination circuit components Q4190, R4193, R4195 and VR4194 (7.5V Zener). Q4190 is a Darlington transistor, test accordingly. If you supply the correct voltages to the circuit, there is not much else that can go wrong.
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Michael Lynch
Dardanelle, AR
Michael W. Lynch