There is one HP-3421A that does not turn on (+15, -15, + 5V is dead).
The measured value of C708 where oscillation is occurring inside the capacitor is 495(0.205).
C708(25V, 470uF) was replaced.
And when you turn on the power, +16.9V is measured in TP700, +7V in RT700, and +6.6V on top, regardless of S502(Switch).
However, +15V, -15V, and +5V cannot be measured.
I suspect the U702(LM393N, Dual Differential Comparator), but it is not easy to analyze because there is no circuit diagram.
If the ¡°Wakeup Logic¡± on the left side of the figure can be related to S502, the problem is complicated, so I need a schematic.
Please tell me where to buy the service manual schematic(pdf, jpg).
?
