High Voltage generator
MAMMOMAT Balance
SPB7-115.840.01 Page 35 of 62
Siemens AG
Troubleshooting Guide
Rev.02 10.04
Medical Solutions
1)
kV vs. VTP1 values are only valid if reference voltage measured on TP8 is
5.00 Vdc (standard calibration). If not, new VTP1 can be calculated wth the
following formula: VTP1(new) = (VTP1(table)/5.00) * VTP8
2)
If necessary kV values can be corrected by means of RV5 (PCB 94-132).
RV5 has influence on the whole kV range, adjust kV at 28 kV as pivot point.
3)
kV values are not affected by the mains voltage within the specified limits
4)
kV values are not affected by the anodic load within the normal operating
range.
5)
Measurement of kV value MUST be done only in MANUAL mode since in
Automatic mode exposure is always preceded by pre-exposure pulse.
6)
X-ray beam is pulsed to avoid grid artifact with grid table, to avoid H.V
interruption use grid-less table or remove grid table or press [RESET
alarm]+[kV+] buttons ( valid for the next exposure only ) or set DIP4 SW1
PCB 01-170 to ON for permanent interruption disable.
7)
kV values are not affected by replacement of inverter block or H.V.
transformer and no kV calibration is necessary if kV value has not been
corrected with RV5. After repair kV check is anyway necessary.
Test points and adjustment
PCB 94-132
TP1 kV check according to conversion table
TP2
ground
TP3
ground
TP4
+5 Vdc
TP5
HIGH + 13 Vdc during exposure
TP6
reference frequency 50 kHz
TP7
kV control from CPU 1/100 VTP1 ( valid in PREP and EXP )
TP8
+5.00 Vdc reference (standard calibration)
TP9
not used
TP10
internal input v15 Vdc
NOTE