T- 2.1.0 Power Logic Board Pin 7 4.0 Volts Or More/Isolate Diode 17 (D17) - Fresenius Medical Care 2008K2 Troubleshooting Manual

T- 2.1.0 POWER LOGIC BOARD PIN 7 4.0 VOLTS OR MORE / ISOLATE DIODE 17 (D17)
A bad diode 17 (D17) destroys Power Logic Boards. Its RESISTANCE (Ω) is checked here:
CAUTION!
a) Turn the machine OFF and unplug it! Electrocution hazard if NOT unplugged!!
b) Per the Figure below, open the power supply to see the component side of the Power Control board.
c) The twenty (20) and nine (9) pin* cables MUST be unplugged! BEFORE unplugging the nine pin cable
NOTE its polarity (i.e. orange wire on the right)!
Set the meter to RESISTANCE (Ω)!
d)
e) Per the Figure above, check D17 by placing one meter
lead on one side of it and the other lead on the other
side.
f) Figure right, reading the meter's numeric AND units
display! TWO (2) possible scenarios:
IF (and ONLY if) between 900 and 1500 Ω (0.900 and 1.5 KΩ)!
1)
See procedure number
2) IF less than 900 Ω (0.900 KΩ) OR more than 1500 Ω (1.5 KΩ):
Perform parts a THROUGH c below:
a) Replace BOTH the Power Control board* (inside the power supply) AND the Power Logic board
(inside the card cage) with known good. *It is a good idea to check diode 17 on the new Power
Control board.
b) After BOTH boards are replaced, leaving NTC #2 unplugged, see procedure number
(page 270).
T- 2.1.4 (page 270).
2008K/K2 Troubleshooting Guide
P/N 507298 Rev. H
Diode 17 is good!
Diode 17 is bad!
T- 2.1.4
Page 269