Fluke 2180A - Manual (Page 77)

21X0A-006
disable the addressing circuit (U4-13) while WRT stays
low to enable the Limits Exceeded input (U5-8) so that
DCLK can clock the data into the latch (U5-1). A Limits
Exceeded indication clocks a high into the latch resulting
in a low at the output (U6-12) to turn on C R l . The limit
not exceeded or another function selected, loads a low
into the latch to turn off the indicator.
606-27. CALIBRATION
606-28. The Limits Option has no variable components
and does not require calibration.
606-29. TROUBLESHOOTING
606-30. Troubleshooting for the 2180A Option -006,
Limits, consists of the tabular flow chart in Table 606-1.
When a step on the flow chart is completed, check for a
decision transfer. If no decision is required, perform the
next step of the table in sequence.
606-31. LIST OF REPLACEABLE PARTS
606-32. Table 606-2 is a list of replaceable parts for the
Limits Option. Refer to Section 5 for an explanation of
the columnar entries.
Table 606<2. Limits Option Troubleshooting
STEP
IMO.
ACTION
Go to the step
number given
for correct
response
YES NO
NOTE
These tests are based on the assumption that the 2180A/2190A has been thoroughly
checked out and is free of troubles prior to beginning the test of the Limits Option —006.
1 Select the less than or equal function and set the thumbwheels for a numeric such that the thermocouple
input exceeds the preset numeric (e.g., thumbwheels set at +1111 and the ambient temperature used as the
thermocouple input).
2 Does the LIMIT indicator illuminate and the rear panel relay contacts close? 26 3
3 Is the +4 Vdc input from the Main PCB present? 5 4
4 Check the +5 Vdc input, repair as required then resume at Step 1.
5 Does the signal at U1-1 toggle (vary between logic high and logic low) when viewed with a scope? 13 6
6 Do the WRT, WRTADR and DCLK lines toggle? 8 7
7 Check the inputs on the cable from the microprocessor on the Main PCB. Repair as required then resume at
Step 1.
8 Does the DATA line toggle? 10 9
9 Check the cabling and Q1, Q2, U3-8 and their associated components. Repair as required then resume at
Step 1.
10 Are the clock and data signals present at pins 1 and 15 of U2, respectively? 12 11
11 Check L)1, U2-2, 11,12,13 and U3. Repair as required then resume at Step 1.
12 Check U4 for the clock and U6 for loading of the data line. Repair as required then resume at Step 1.
13 Is the function code a BCD 0 with pins 4, 5, and 6 of U7 low, the sign (+) at U7-7 high, the numeric MSD
BCD code as set at pins 1,15,14 and 13 of U9, the second MSD BCD code as set at pins 4, 5, 6, and 7 of U11 ?
15 14
14 Check the switches and their associated components. Reapir as required then resume at Step 1.
15 Is the clock present at U7-10, U9-10, and U11 -10? 17 16
16 Check U4-10, U1-13 and their inputs. Repair as required then resume at Step 1.
606-3