HP 5890 SERIES II Service Manual page 13

H2 ALARM - EPP B indicates electronic pressure problem with
the B systems ability to hold pressure. Possibly a leak, trouble shoot the proportional control valve,
pressure transducer and the inlet in the case of the EPC. Trouble shoot the forward pressure regulator
and gage in the case of the MPC.
The FAULT: message indicates that a major subsystem of the HP 5890 SERIES II is not functioning
properly. Although the operation of the suspected subsystem is suspended until the problem is cor-
rected, the balance of the GC is operational. Note that the instrument can never reach a fully READY
state when a FAULT condition exists.
FAULT: ADC OFFSET indicates a problem with the thermal ADC offset reading. Replace the Main
Board.
FAULT: LINE SENSE indicates a problem either with the actual line voltage or with the sensing circuit.
Measure the line voltage and if the measurement is between +5% and- 10% of the instruments stated
rating then the line voltage is O.K. Determine if the 120 VAC secondary exists and if its fuse (F3) is
open. If both F3 and the 120 VAC secondary are good then their is a failure in the line sense circuit and
the main board should be replaced.
FAULT: OVEN > MAX+20 indicates that the oven senses its temperature has exceeded the current
setpoint value by more than 20 degrees C. This message (as any FAULT message regarding a tem-
perature problem) shuts down all of the temperature systems. The problem could be either in the oven
sensing or in the oven control circuits. List the oven temperature; if the display indicates that the actual
valve is above 800 degrees C, most likely the oven sensor is open (although it could be some compo-
nent in the sensing circuit). If the actual value of the oven temperature seems reasonable, the problem
is likely to be in the oven control circuitry.
FAULT: (ZONE NAME) TEMP RDG where the ZONE NAME could be OVEN, INJA, INJB, DETA,
DETB, or AUX. Any of these messages indicates that the specified zone (or oven) temperature reading
was out of acceptable range. This most often is the result of an inoperative sensor in the named zone.
FAULT: (OUTPUT NAME) TEST where the OUTPUT NAME could be DAC1, DAC2, ATTN1, or
ATTN2. If thermal fault messages also appear, suspect the A/D Converter circuitry. The A/D Converter
section of the Main Board is used to measure DAC and ATTN outputs. However, if only this test mes-
sage appears, the most obvious area to suspect is the D/A Converter portion of the appropriate board.
DAC2 or ATTN2 indicates the D/A section of the Interface Board; whereas the DAC1 or ATTN1 indi-
cates the D/A portion of the Main Board. Other areas that could be at fault include the CPU and A/D
sections of the Main Board, but are less likely. Occasionally, multiple faults messages may exist at the
same time. Only the last message to occur will automatically be displayed on the front panel of the in-
strument. Others will be retained in the instrument' s memory. By pressing the CLEAR key, the instru-
ment will roll through all of its Not Ready states (which include all FAULTs).
FAULT: EPP RAM TEST indicates the RAM has failed selftest. This requires board replacement.
FAULT: EPP ROM TEST indicates the ROM has failed selftest and should be replaced.
FAULT: INET CPU indicates that the Communications Interface Board is not responding properly. Typi-
cally, this message is caused by a faulty microprocessor (CPU) on the Interface Board.
FAULT: INET CPU RAM indicates that the read/write memory internal to the CPU on the Interface
Board is not functioning as expected. Replace either the Interface Board or its CPU.
SVC 1- 6
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