HP 13255 Technical Information page 10

13255
Power Supply Module
13255-91142/08
Rev SEP-06-77
3.0 FUNCTIUN4L
DESCRIPTION. Refer to the module block diagram (figure
1),
sChematic diaorams (figures 2 and 3), timing diagram (figure 4), compo-
nent location
diaqram~
(tiqures
5
ana
6),
ana parts lists (02640-60169,
02640-60130, 02640-60142,
and 02640-60148) located in the appendix.
As snown in
the
clock diaqraffi, the Power Supply Module consists of
two printed-circuit assemblies, the power Supply PCA and the Power
Supply Control
peA.
3 • 1
PO tHo:
t-\
S
tJ
p PLY
peA.
3.1 • 1
3.1 .2
3.1.~
The
yOWpr
~uPplv
peA contains all of the high-level electronics of the
power
su~plv.
This assemhlv connects to the power line and supplies
power to the terminal data bus and Sweep Module.
Line Rectifier.
The line rectifier block connects to tne power line and rectifies and
filters the incoming ac power. The line voltage select switching is
done by fuse location and confioures the rectifier eittler as a voltage
aoubler (t1S-volt operation) or as a bridge rectifier (230-volt opera-
t
i
on) •
Logic
~ower
Supply.
The logic power supply block also connects directly to the oower line.
Its function is to proviae power to the Power supply Control PCA and
driver transistors in the chopppr bloCk. The logic power supply has
two outputs, +16 volts unreaulated and +5 volts regulated
(+5C).
Chopper.
The chooper blOCK contains two power transistors (Q3,Q4) in the primary
circuitry and two driver transistors (Ql,Q2). The driver transistors
are driven
by
alternating pulses Which come from the Power Supply
Control PCA. The fllnction Of the chopper clOCk is to chop tne dc out-
put from the line
r~ctifier
block and aoply the chopped Signal to the
power supply main
transf~rmer
(T2). The basic power supply regulation
taKes place durinq this chopping operation as the average output vol-
tage is proportional to the width of the pulses applied to the Chopper.
Current sensing takes place
1n
this block ana is applied to a current
limit circuit on the Power Supply ContrOl PCA.