P- F.2.0 Screen Remains 'Black'/Isolate +12 And +5 Volts At Backlight Converter; P- F.3.0 Troubleshoot A Black Screen - Fresenius Medical Care 2008K2 Troubleshooting Manual

P- F.2.0 SCREEN REMAINS 'BLACK' / ISOLATE +12 AND +5 VOLTS AT BACKLIGHT CONVERTER
a) Per the Figure below, measure for +5 AND +12 volts DC (V
BE CERTAIN the meter lead contacts the metal portion of the connector! TWO (2) measurements:
Measurement #1: Where the red wire is connected. Good = between 11.7 and 12.3 volts DC
Measurement #2: Where the white wire is connected. Good = between 4.7 and 5. 3 volts DC
b) BOTH +12 and +5 volts DC good?
Yes BOTH +12 and +5 good! See procedure number P- F.3.0 (page 603).
No Referring to the Figure below, THREE (3) possibilities: 1) Bad Data Cable* (between the
Motherboard and the Display Board) OR; 2) Bad Backlight Converter Cable (between the High
Voltage Power Supply and the Display Board) OR; 3) Bad High Voltage Power Supply.

P- F.3.0 TROUBLESHOOT A BLACK SCREEN

Referring to the Figure above:
a) Turn the machine OFF!* then ENSURE ALL screen and High Voltage Power Supply cables are plugged
WARNING!
in correctly. *
b) Turn the machine on. If (and ONLY if) the white backlight STILL does not turn on continue to part c.
c) Turn the machine OFF then swap in a known good Backlight Converter Cable (between the High
Voltage Power Supply and the Display Board).
d) Turn the machine ON. If (and ONLY if) the white backlight STILL does not turn on continue to part e.
e) Turn the machine OFF then swap in a known good High Voltage Power Supply.
f) Turn the machine ON. If (and ONLY if) the white backlight STILL does turn on swap in a known good
screen.
Figure 114 – Back Light Supply Voltages
VERY HIGH VOLTAGE if the machine is not off!
2008K/K2 Troubleshooting Guide
P/N 507298 Rev. H
) inside the backlight converter connector.
DC
Page 603