Smart AY Tango Service Manual page 43

Try disconnecting the ribbon cable. If this fixes the problem, then the fault is
actually on the ribbon cable or the HKPID or LCDENC PCBs.
If the entire PCB appears dead then it could be a number of things.
Check for power on this module. The main power cable should be connected
and the LED on the PANCPU should be illuminated. Check for power on this
cable (Yellow = 12V, Red = 5V). Lack of power may mean a PSU problem
elsewhere. If you disconnect this cable and measure a voltage from the PSU, it
may indicate a short circuit on the HKLOW PCB which is shutting off the PSU.
Power Cable
Power LED
Check the "talk1" LED on the top left corner of this PCB. If it starts flashing
within 15 seconds of power on, the HKLOW PCB is operating correctly but has
no network connection to the Tango software. Check the network setup (section
20) and make sure the Tango software is all running correctly.
If the power LED on the PANCPU is ON but there is no activity on the HKLOW
PCB (not even a flashing "talk1" LED) then the problem is most likely with the
PANCPU or the firmware. Try changing the PANCPU or see sections 17 and 18
for help in debugging PANCPU / Firmware problems.
Tango Smart Console™ Service Manual
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14 Oct 2009 43