HP 8340A Operating Manual page 338

the interior of the instru ment.
cumulation, a piece of pa per, etc.
power supply failure.
FAN IS NOT OPERATING, LED'S COME ON AT POWER ON, THEN GO OUT
LATER - Refer to the
FAN IS NOT OPERA TING, LED'S OFF AT POWER ON - If all instrument LED's
arc off and the fan is not operating, suspect a problem in the instrument causing
complete loss or ac mains, i.e. transformer, wiring, or line filter module related p rob­
lems. Check the line filter module voltage select card
Installation).
SOME LED's OFF.
panel section is probably the cause.
ALL LED's ON.
memory, or power supply is probably the cause.
CHARACTER MARCH.
marching across them, the instrument processor or memory is probably the cause.
3. FAN
FAN DOES NOT TURN ON.
fan should start running. If it docs not, the fan, power supply, or Kl Relay (inside
the instrument near the rca r panel) is pro ba bl y the ca use.
If the instrument has run for some time with the fan not running, the interior tem­
perature may have risen to the point that the A62SI thermal switch has turned the
instrument off.
reset itself when the instrument cools down.
FAN DOES NOT TUR.N OFF.
fan should not be running.
supply has failed. The fan relay solenoid is
STANDBY mode, turning the ran
supply), the solenoid will
4. INSTR CHECK LED's REMAIN ON
INSTR CHECK LED's I and II
This test sequence is carried out every time the
[INSTR PRESET!
Test. Both LED's should be off after about
INSTR CHECK LED I REMAINS ON.
rela ted problem. Suspect the microprocessor, memory, or Peripheral Interface Timer.
INSTR CHECK LED II REMAINS ON.
Data bus, or I/0 Address bus-related problem.
A57 Markcr/Bandcross board.
HP 8340A - Appendix A
Make sure the fan filter is not blocked by dust ac­
If the instrument's air flow is good, suspect a
FAN section, below.
If some LED's that should be on are off, the instrument's front
If all of the LED's and annunciators arc on, instrument processor,
If the four display windows have strings of characters
When the
If so, all front panel LED's will have gone off.
When the instrument is in the
If it is, the Fan Relay (Kl) may be stuck, or it the +22V
off.
de-energize, turning the fan
show the results or the instrument Self-Test sequence.
is pressed. These LED's come on immediately upon initiating Self­
- 4 -
Scans by HB9HCA and HB9FSX
POWER switch is turned
energized when the instrument is in the
If the power to the relay solenoid fails (+22V
on.
POWER switch is turned on or when
1 second.
Indicates that there is a Processor board­
Indicates that there is a Marker RAM, 1/0
The Marker RAM is located on the
(Refer to Section ll,
ON, the instrument
The switch will
STANDBY mode, the