Tektronix CSA 803C Marine Radio User Manual


 
Diagnostic Troubleshooting
CSA 803C Service Manual
6Ć89
The CSA 803C holds four lithium batteries to provide power when the instruĆ
ment is turned off. The following discussions provide criteria for determining
if a battery has exceeded its lifetime, and is thus causing incorrect instruĆ
ment operation. (A battery's lifetime will typically exceed five years.) If the
battery voltage measures (at 20_ C) equal to or greater than the voltages
listed in this section, then the circuit should operate correctly from 0_ C to
50_ C. (These voltage measurements are taken with the instrument power
off.)
Battery BT130 provides power for the real time clock on the A14 I/O board. If
the clock begins to lose time rapidly when the instrument is turned off or the
diagnostics report that the Real Time Clk (E42XX) has failed, the battery
should be tested. If the battery voltage measures less than 2.7 V, then the
most likely source of the problem is the battery and you should follow the
instructions for battery disposal earlier in this section.
Battery BT150 provides power for the nonvolatile RAM (NVRAM) on the
A18 Memory board. If the diagnostics consistently reports an NVRAM
Battery (E141X) failure over multiple powerĆons, then the battery should be
tested. If the battery voltage measures less than 2.7 V, then the most likely
source of the problem is the battery and you should follow the instructions
for battery disposal earlier in this section.
Sockets for devices U500 and U511 provide power for the NVRAM on the
A5 Time Base/Controller board. If the diagnostics consistently report a Static
RAM Battery (T1331) failure over multiple powerĆons, then the batteries
should be tested. If either one of the battery voltages measures less than
2.1 V, as measured on pin 28 (Vcc), follow the instructions for battery disĆ
posal earlier in this section. (It is recommended that both batteries be reĆ
placed at the same time.)
NOTE
Turning the instrument off while Extended Diagnostics is executing
one of the NVRAM memory tests may cause failure of the NVRAM
battery test. If the diagnostics report an NVRAM battery failure, then
exit the diagnostics. This will rewrite the confidence words into the
NVRAM. Turn off the instrument for at least one hour. Then, turn the
instrument back on. If the diagnostics still indicate an NVRAM
battery failure, then the battery should be tested.
Battery Testing