9
Baker Instrument Company
The Measure of Quality
measuring across resistors R1 through R10. Good measurements will be 70K ohms
or higher. Replace any SCR’s found to be shorted.
4.
Check U2 pin 7 on the I/O board, this should be a zero (0) volts DC, if at five (5)
volts DC then replace U2 and U7.
5.
Check Q3 on the I/O board for a collector to emitter short, if so replace Q3.
6.
Check for shorted Hipot trip lamp on the A/D board, if so replace D3.
H
IPOT CURRENT BAR
/
DISPLAY NOT PRESENT
1.
Check continuity from test lead one (1) alligator clip to deck one (1) of the selector
switch.
2.
Check continuity from test lead ground alligator clip to the metal spacer adjacent to
D1 and D2 on the Discharge board.
3.
For the purposes of troubleshooting this circuit, set up will require the tester to be in
the Hipot mode with leads one (1) and ground connected to a 10 megohm 35 watt
resistor. Use a digital multimeter from these measurements with the negative lead of
the meter connected to pin 29C on the I/O board. Set tester to 100
µ
A/division.
4.
Measure at U11 pin 3 on the I/O board and raise output control to 6 kV. The
measurement should increase negatively as more current is drawn through the test
load. At 6 kV this should be approximately -.040 volts DC. Measurement at the
output U11 pin 6 on the I/O board should be identical. If not replace U11.
5.
Measure at U10 pin 6 as the output control is raised to 6kV. At 6kV, this
measurement will increase to approximately 2.9 volts DC. If not replace U10.
6.
Measure at RPK1 pin 15 and then pin 2 for the output as described in step 5, if not
present at RPK1 pin 2, Replace RPK1.
7.
Measure at U25 pin 8, use a 10X scope probe, set scope to 1 volt/division and 5 ms
and an internal trigger at the 3 volt level. Raise output of tester to 6kV across the 10
megohm load. Measure for approximately 3 volts with a negative going square wave
approximately .4 volts at a 5 ms duration. If not present, replace U25.
8.
Measure at U22 pin 18 for the same signal as in step 7 and then measure at U22 pin 9,
the output of u22 should be doubled to approximately 6 volts with the same negative
going square waveform. If not replace U22.
9.
Measure at U23 pin 7, if same measurements taken in step 8 is not present, replace
U23.