Section Iv - Theory Of Operation; Introduction; General Functional Overview; Crt - Beehive International B102 Service Manual

SECTION IV
Theory of Operation
4.1 INTRODUCTION
bly. The DC regulators used in the B100 Series
terminals are overcurrent and thermally protected.
The TOC type regulator is a 10 amp in the B100/
B102 and a 2 amp in the B150/B152 and is mounted
to the chassis via a large finned sink. The regulator
subassembly is connected to the Logic Board
through a cable assembly (see Figure -3). For
identification and specific regulator replacement,
consult the B100 Series Illustrated Parts Breakdown
under Section III, "Major Assembly Components."
RECTIFIER
RECTIFIER
TRANSFORMER
♦5
REGULATOR
IS
REGULATOR
ISvOC
This section of the Service Manual contains the
Theory of Operation for th6 B100 Series terminals.
This discussion is presented as a functional descrip
tion at a detailed block diagram level referencing
appropriate functional blocks on the diagram. This
manual is intended to help the customer service the
terminal to a subassembly level. Individual compo
nent replacement Is not discussed in detail and the
customer is advised to send subassemblies to a quali
fied Beehive repair area for service, if required.
It should be noted that all BlOO Series terminals
operate similarly and are essentially identical. Where
there are critical differences, however, the manual
will indicate these with separate explanations.
4.2 GENERAL FUNCTIONAL OVERVIEW
The B10G Series consists of four basic functional
components: the main Logic Board (with Power
Supply), the keyboard, the CRT with electronics,
and small separately mounted chassis components
(i.e., fan, switches, filter, and regulator/transformer).
Figure 4-1 shows the basic functional block diagram
of the terminal. These functions are briefly described
in following paragraphs. Note that there are two
two different versions of the block diagram: Figure
4-1 describes the B100/B102 and Figure 4-2 de
scribes the B150/B152.
4.2.1 PowQr Supply
The Power Supply provides the required, regulated
DC voltages to the terminal. This assembly will
operate on 100, 115 or 230 VAC power 50/60 Hz.
Section II of the Operator Manual contains Power
Supply voltage change information.
The Power Supply provides +5, +15, +12, —12 VDC
to the circuitry from a standard AC sourca Figure
4-3 is a block diagram of the Power Supply subassem
^ 15/230 vACINPUT^
BLOCK
12
REGULATOR
4-1
RECTIFIER
-12
REGULATOR
l2vOC
-l2vOC
Figure 4-3 Power Supply Block Diagram
The power applied to the Power Supply is stepped
down in voltage. The transformer output voltages
are rectified by three bridge circuits. The output
from the rectifiers and filters provides power to
the +5, +15, +12 and —12 VDC regulator circuits
These components are located on the Logic Board.
The main transformer is chassis mounted and con
nected to the Logic Board through a cable assembly
(see Parts Manual Section III).
4.Z2 CRT
The Monitor Assembly includes a 12 inch (30.5 cm),
diagonally measured, CRT and its supporting solid-
state circuitry. The nronitor is controlled by the