Description of boards 21
9.2.1) BOARD 15.14.250 "UPFR SECTION" (fig. 17)
UPFR preregulator: supplies stabilized voltage (approx. 385Vdc) to electrolytic capacitors to power the power inverter. In addi-
tion, this stage sees that current absorbed from the supply mains is sinusoidal (power factor = 0.99). Toroidal inductor L1 is
also included in this stage (see point "f" in fig. 7 in sect. 6.1)
WARNING:
before taking measurements described
, open solder-jumper K2 with the machine unplugged!
Power source / Mode
Component
Test point
Value
OFF
DD1
A K
+0.34 Vdc
OFF
MF7
S D
+0.36 Vdc
OFF
MF7
S G
+0.25 Vdc
OFF
MF9
S D
+0.36 Vdc
OFF
MF9
S G
+0.25 Vdc
OFF
R89
-
46 OHM*
Power source / Mode
Test point
LED
Value
ON/TIG
-
L10
FAST BLINKING
ON
RV1 RV2
-
230 Vac ± 20%
ON
TP34 TP10
-
+7.7 Vdc ± 20%
ON
TP20 TP10
-
+385 ± 5 Vdc
ON
RL1
-
CLOSED*
* Note = wait 10 minutes after switching off the power source before measuring R89
* Note: RL1 closes a few seconds after the power source is switched on
Unless otherwise specified, all measurements sholud be taken with the boards in their slots and connected accordingly
