Diagnose Routines - Tektronix 2246 1Y Service Manual

Maintenance—2246 1Y and 2246 Mod A Service
DIAGNOSE Tests
The complete DIAGNOSE routine may be called up
by the service technician as needed to aid in
Error Label
INTERFACE ERROR
RAM ERROR
(RO RAM)
6-16
Table 6-6

DIAGNOSE ROUTINES

Path, devices tested, and troubleshooting actions
Measurement Processor to Readout Processor Communications.
WROTE (hex number that was written, 2 characters).
READ (hex number that was read, 2 characters).
This test rotates a 1 through the byte on the bus lines. The difference
between WROTE and READ indicates which bit is stuck.
Devices to troubleshoot:
U2401, U2402, U2417C and D, and bus lines between Measurement Proc­
essor and Readout Processor.
Check U2501 pin 29 for enabling signal to U2402, and U2400 pin 22 for
clock.
Writes and reads test bytes from the Readout RAM (U2406).
ADDRESS (hex address of error location, 3 characters).
WROTE (hex data written, 2 characters).
READ (hex data read, 2 characters).
The difference between WROTE and READ data indicates a stuck bit.
PART NUM (Tektronix Part Number without dashes).
EXPECTED CHECKSUM (hex number, 2 characters).
ACTUAL CHECKSUM (hex number, 2 characters).
Readout ROM is internal to the Readout Processor,
U2400; a failure of this test may mean a bad Readout
Processor.
troubleshooting the instrument. Testing routines and
troubleshooting information for use in the event of a
failed test are given in Table 6-6.
NOTE