Fluke 45 - 8-14. Troubleshooting; 8-15. Power-up Problems

45
Service Manual
8-10
140 IA% = 0% ! instrument IEEE address
150 S% = -1% ! initialize spl response
160 TERM ! terminate input only on EOI
170 INIT PORT 0 ! initialize IEEE-488 bus
180 CLEAR @IA% ! selective device clear
190 PRINT @IA%,"*cls" ! clear instrument status
200 ON SRQ GOTO 530 ! enable SRQ interrupt
210 PRINT @IA%,"*cls;*sre 16;*idn?" ! SRQ on Message Available
220 WAIT 500% FOR SRQ ! allow time to execute commands
230 IF S% >= 0% THEN 260
240 PRINT "Instrument failed to generate a Service Request"
250 STOP
260 PRINT "Serial Poll =";S%;"(should be 80)."
270 PRINT "Identification Query Response = ";R$
280 STOP
500 !
510 ! Service Request interrupt
520 !
530 S% = SPL(IA%) ! get instrument serial poll status
540 IF S% AND 16% THEN 550 ELSE 560
550 INPUT LINE @IA%,R$ ! if MAV set get the response
560 RESUME 230 ! end of SRQ interrupt
999 END
Figure 8-4. IEEE-488 Interface Performance Test
8-14. Troubleshooting
8-15. Power-up Problems
The following discussion identifies probable fault areas if the installation of an IEEE-
488 Interface Option causes power-up failure for the Fluke 45. The problem is probably
a short on A5P2 or A5P3; the Microprocessor on the Main Assembly is prevented from
accessing ROM and RAM correctly. Two extender cables are available (PN 867952 and
867957) to assist during troubleshooting.
• The first thing to check is whether GND is shorted to either VCC or VCC2 on the
IEEE Assembly.
• The short may also be an interface signal to either VCC, GND, or another interface
signal. The logical signals to check are DATA(7..0), ADD(15..0), RD*, WR*, E, and
RESET*.
• The short may be due to a CMOS input that has been damaged from static discharge;
the short is then detectable only when the circuit is powered up. Use an oscilloscope
to check activity on each of the interface signals. Verify that signals are able to
transition normally between 0 and 5V.
8-16. Communication Problems
8-17. Failure to Select IEEE-488 Interface Option
IEEE-488 Interface selection procedures are described in Chapter 3.