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5. Check U25 pin 4 on the A/D board for the same increase in voltage, if not present,
check connection between U3 pin 6 on the I/O board and RPK1 pin 16. Then check
RPK1 pin 16 to RPK1 pin 1 for 47K ohms resistance. If open replace RPK1.
6. Check U25 pin 8 for a 2.5-volt positively pulsed waveform with a frequency of
200ms with the tester set at 6kV output with no current deflection on the CRT. If not
present check U25 pins 1, 15, 16. Only pin 1 should have a signal which should be a
5-volt waveform pulsing negatively to zero (0) volts every 200ms. If these signals
are present at pins 1, 15, and 15 with a measured input at U25 pin 4 then replace U25.
7. Check U22 pin 9 for a 5-volt positively pulsed waveform with a frequency of 200ms.
Set the tester to 6 kV output with no current deflection on the CRT. If not present
replace U22.
8. Check U23 pin 7 for the same signal. If not present, replace U23.
S
ECONDS
1. The seconds/division display is controlled by switch S1 on the I/O board and pull up
resistors R40, R41, R16, R2, R3, R4, R19, R20, and R43. This in turn connected to a
series of AND, NAND and Inverter IC' s set up to control a binary pattern for control
lines Sweep A, B, C, and D. See4 binary chart on the I/O board. A typical fault
would be seen as a duplication of any one of the possible displayed sweep settings
such as CHANGE, 2µS, 6µS, 10µS, 20µS, 60µS, 100µS, 200µS, 600µS, or 1mS.
Possible failures can include a logic gate stuck high or low such as U1, U8, U4, U5 or
U6 or mux U18. Check the pull up resistors listed above. Check that S1 grounds
sequentially as it is rotated.
2. The volts/division display is controlled by switch S2 on the I/O board and pull up
resistors R10, R8, and R11. This in turn is connected to a series of Inverters and/or
gates to set up a binary pattern for control lines V DIV 1 and V DIV 2. See binary
charge on the I/O board. A typical fault will be seen as a duplication of any one of
the possible volts/division settings such as 500 volts, 1000 volts, 2000 volts, or 3000
volts. Possible failures can include a logic gate stuck high or low such as U4 or U5 or
mux U17. Check the pullup resistors listed above. Check that switch S2 grounds
sequentially as it is rotated.
3. The µ/A division display is controlled by switch S3:A on the I/O board and pull up
resistors R36 and R38. This in turn is connected to a series of Inverters to set up a
binary pattern for control lines µA/DIV 1 and µA/Div 2. See binary chart on the I/O
board. A typical fault will be seen as a duplication of any one of the possible µA/
/D
, V
IV
OLTS
FUNCTION DISPLAY INCORRECT
Baker Instrument Company
The Measure of Quality
, µA/D
/D
IV
IV OR
.
12
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