Siemens ST750 - Figure 41 - Handset

ST750 GENERAL HANDBOOK
667/HB/33750/000 Page 107 Issue 6
Figure 41 – Handset
0000
00
0 = - -
1 = - E
2 = F –
3 = F E
0 = - - - -
1 = - - - A
2 = - - B –
3 = - - B A
4 = - C - -
5 = - C – A
6 = - C B –
7 = - C B A
8 = D - - -
9 = D - - A
A = D – B –
B = D – B A
C = D C - -
D = D C – A
E = D C B –
F = D C B A
0000
00
0
2
So in the above example, there are no voltages on Phase B amber (or Wait). Has
the wait fuse blown?
• On power-up, the self-test facility checks the integrity of the main processor
board:
RAM FAULT
DPR RAM FAULT
PRG PROM FAULT
XTL FAULT
DPR R/W FAULT
All the above faults point to problems internally on the main processor card.
• Checks communications with the secondary / phase bus processor:
P/Bus CPU....
If the processor cannot be detected, then the self-test will wait indefinitely at this
point with the red system error LED illuminated. Check that the processor and its
firmware are fitted.
• Examines the lamp switch cards to see how many are fitted:
No L/S Cards Found
No cards were detected. Either the lamp switch or the processor PCB could be
faulty.
• Waits for ZXO synchronisation and checks the mains frequency: