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division settings such as 100µA, 10µA, or 1µA. Possible failures can include a logic
gate stuck high or low such as U6 or mux U17. Check the pull up resistors listed
above. Check that switch S3:A grounds sequentially as it is rotated.
4. The function display is controlled by switch S3:A on the I/O board and pull up
resistors R42, R12, and R14. This is in turn connected to a series of Inverters at U6.
A typical fault will be seen as the CRT display not matching the function control
knob. Possible failures can include a logic gate stuck high or low such as U6, U5,
mux IC' s U17 or U15. Check pull up resistors listed above and also pull up resistors
at RPK3 pins 8 and 9. Check that switch S3:A grounds sequentially as it is rotated.
P
RINTER DOES NOT WORK PROPERLY
1. Check that the printer cable is plugged into the printer port.
2. Check for faulty or damaged printer cable by checking continuity between all 25 pins
in both ends. Try a replacement printer cable.
3. Digital models with a serial number 001 through serial number 370 or ones
manufactured before December 1997 must be used with an Epson FX dot matrix
printer. And it must be configured properly to interface. Firmware revision 1.35 is
used with the Epson dot matrix printer. Digital models after serial number 370 or
ones manufactured after December 1997 will have firmware revision 1.36 which will
use an Epson DeskJet 600 printer.
4. Check for faulty printer, try a substitute printer.
5. Measure with a 10x-scope probe the following points on the I/O board. To activate
these signal lines a printer will need to be connected and the print softkey will need to
be depressed. Monitor PRN DB0 through PRN DB7 from U14 on the I/O board for
data transfer. Data transfer is defined as a 5-volt logic level that changes in frequency
of pulses as the data transfer sequence changes. Set the oscilloscope to 5
volts/division and a 5ms-sweep rate. If this output is not det4ected on one or more
printer lines, check the resistance of all resistors in RPK2. Replace if defective. If
RPK2 checks good, replace U14, U16, and U9. Check also the resistance of RPK1
and R50 through R54. Replace if necessary.
1. Upon power up if no display is seen on the CRT, the first step to ensure is that the
intensity output potentiometer is turned clockwise are enough to see a display,
generally at least a 2 O' clock position should be sufficient.
N
B
O
AKER
Baker Instrument Company
The Measure of Quality
L
OGO DISPLAYED
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