Keithley 7001 User Manual

Maintenance
7-13
Tests 103.1-103.2  Digital output bits 1-4
Failure of Tests 103.1-103.2 suggests a micro DIN board
error.
NOTE
With some Þrmware revisions, the digital output tests
(103.1 through 103.4) will not pass if the built-in test re-
sistors are not present. (See paragraph 4.9.1)
These tests make use of the fact that the 68302 Port A
registers are bidirectional even though in normal use
they are programmed as outputs only.
Diodes and resistors are connected around the 2596 so
that OUT 1 feeds back to PA5, 2 feeds back to PA6, 3 to
PA7, and 4 to PA4. (Note that signal numbers are
scrambled at the 2596 open collector driver. The num-
bers in the above description refer to the digital output
signal numbers, not to the numbers on the 2596.)
During Test 103.1, PA4 and PA6 are programmed as
outputs, PA5 and PA7 are programmed as inputs. As
PA4 (OUT1) is toggled high and low the signal is veri-
Þed at PA5.
During Test 103.2, PA5 and PA7 are programmed as
outputs, PA4 and PA6 are programmed as inputs. As
PA5 (OUT2) is toggled high and low the signal is veri-
Þed at PA6.
Tests 103.3-103.4  OUT3 and OUT4 (test similar to
103.1-103.2).
Success of these tests assures the basic functionality of
PA4-7, the 2596 and associated components. A failure
may be caused by shorted or defective components or
by open or shorted PC board traces.
Tests 103.5  Digital Input
Failure of Test 103.5 suggests a micro DIN board or dig-
ital board error.
This test veriÞes that the digital input signal is pulled
high at PB8 of the microprocessor (U107). Success of
this test does not guarantee functionality. A failure may
be caused by a defective component or a short circuit.
Test 104 (IEEE-488 Test)
Failure of Test 104 suggests a digital board error.
The IEEE-488 interface in the Model 7001 consists of
the 9914 GPIB chip (U104), and the 75160 (U101) and
75161 (U100) bus drivers. The 75160 buffers DIO1-8
data lines, the 75161 buffers the bus handshake lines
and other control signals. The circuitry to test these
parts is contained in the 5064 ASIC (U103).
Test 104.1  Handshake Test
Failure of Test 104.1 suggests a digital board error.
Circuitry in the 5064 is set up to simulate an IEEE-488
handshake. Bytes are written to the 9914 Data Out reg-
ister and the interrupt status register is checked to ver-
ify that a Byte-Out handshake is completed.
These tests verify the basic functionality of the 9914,
75161, and the handshake portion of the ASIC (Signals
BNRFD, BNDAC, and BDAV). Failures may indicate
that a part is defective, or that the PC board is faulty.
Check U100, U103, U104.
Test 104.2  IEEE-Data
Failure of Test 104.2 suggests a digital board error.
Bytes are written to the 9914 Data Out register to drive
and release bus line DIO1. The state of this signal is
veriÞed at the 68302 through PB0 (BITB1).
These tests verify the basic functionality of the 9914
and 75160. Failures may indicate that a part is defective
or that the PC board is faulty. Check U101 and U104.
Test 105  Trigger tests
Failure of Test 105 suggests a micro DIN board or digi-
tal board error.
Triggers in the Model 7001 are controlled by circuitry in
the 5064 ASIC (U103). This part has seven trigger out-
puts (STO1-STO7) and eight trigger inputs (STI1-STI8).
The system trigger bus is controlled by STI1-STI6 and
STO1-STO6.
STO7 is connected to the CHANNEL READY BNC
connector. STI7 is connected to the EXTERNAL TRIG-
GER BNC connector.
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Keithley 7001 Specifications

General

Brand	Keithley
Model	7001
Category	Switch
Language	English