OVEN OSCILLATOR POWER SUPPLY
The Oven Oscillator Power Supply board (A1 12)
is
a
simple 28V regulated, current limited power supply.
U1 and U2 provide voltage regulation, thermal protection and current limiting.
The transformer
TI, CRl, C1 and C2 provide a 40V nominal unregulated DC voltage. The output voltage
is
set by voltage divider R5, R3 and R4. These resistors were selected so that 28V out provides 2.23V
at
U2 pin 2 (to U2 pin 1). Diode CR2 protects the supply from being pulled more negative than ground.
See the schematic in figure 03104105-6.
The power supply (A1 12) is on and operating as long as the counter
is
connected to an active AC power
source. The counter's POWER
ONIOFF switch on the front panel does not control this assembly.
At
C
T
AC
GND
Figure 03104105-4. Oven Oscillator Power Supply (A1 12) Component Location
Scans by ArtekMedia © 2007
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