What To Look For In The Qa History; Max Board Troubleshooting - GE Medical Systems PRODIGY Service Manual

DPX-NT software includes the capability to view, print or graph data contained
in the Quality Assurance database. View and print display selected results of
many of the tests run during the Daily Quality Assurance in tabular form. The
graph feature will graph the results of only one of the Quality Assurance
parameters. All features allow for the user to select the time period to be
examined.

4.15.1 What to Look for in the QA History

All categories should remain steady over time. Check the PASSED column for
failed QA's. If a failing QA is found, try to determine the cause, including
operator error.
The limit for % Spillover is 13%.
If any sudden jumps are noticed in the values of any of the categories,
determine first if these are due to service work such as a Tube Head
replacement. If service work causes a shift in the QA values, then compare
present values to those obtained only after the service.

4.16 MAX Board Troubleshooting

The MAX board controls the current through the X-ray Insert in the Tube
Head. DPX-NT scanners use MAX version 02B currently.
The current at a given kV across the insert is a function of insert filament
temperature. The MAX board adjusts the current by regulating the filament
temperature to provide the proper current as set by the SBC. The relationship
is Insert µA X 1000 = SBC input (in volts DC), so for an SBC input of 5VDC,
Insert µA = 5000.
The Positive High Voltage Power Supply has a current monitor output (mA
MONITOR); the voltage at this output is proportional to the current passing
through the X-ray Insert. This monitor voltage is connected to the MAX board
as feedback (mA FEEDBACK).
What to look for
When the X-ray Relay is on, both the red and green LED's on the MAX board
should be illuminated. If both are out, no power is getting to the MAX board. If
only the red LED is lit, then the MAX board fuse is burned out or missing.
Electrical tests
DPX-NT Service Manual (Rev A- 1999)
• Make sure that all connectors are fully seated.
• Check Lemo connectors for loose parts.
• Check for loose wires on the insulation displacement connectors.
• Check the position of the shorting jumpers on pin headers JB1, JB2, and
JB3 for: Be sure pins 1 and 2 are connected as indicated by silk screen.
Troubleshooting 4-143