_ _ A_u_G_us_T_1_9_a4 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ $TAR*,ECH
MANUFACTS
ATARI SWITCHINCJ POWER SUPPLY
PRECAUTIONS
T
roubleshooting aids are provided
throughout this manual. The following
information is intended to acquaint the service
technician with useful troubleshooting
information.
PRECAUTIONS
Do not troubleshoot the switching power
supply until you are thoroughly familiar with
all precautions described below. Failure to
observe these precautions could result in
serious personal injury or damage to the
power supply.
•
•
NEVER defeat the overcurrent protection
circuit comprised of BR1, U2, and 03. If
this circuit continues to trigger and is
defeated, the power MOSFET 01 and 02
may be destroyed.
When checking the circuitry connected to
the line voltage, ALWAYS use an isolated
oscilloscope.
•
If 01 and 02 fail, replace both transistors
even if one seems to be operating property.
Also, replace R21-R24 even if they seem
to be undamaged.
•
NEVER try to operate only one MOSFET
01 or 02.
•
The 5-volt output must have at least a 1-
ampere load for proper operation. If oper-
ated under no load, the supply will generate
a series of very short pulses.
•
A lightly overloaded condition can cause
the pulse width to be very narrow and may
not set comparator U2 into the latched
condition.
~
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CIRCUIT DESCRIPTION
A detailed circuit description of the switching
power supply is provided in Chapter 3 of your
Atari Service Manual TM-238. Refer to this
description to obtain a thorough knowledge
of the operation of the supply circuitry before
attempting to troubleshoot.
NEW-TONE ELECTRONICS, INC.
DEPT. STJ
44 Farrand St. • Bloomfield, NJ 07003
STAR*TECH
JOURNAL
AL'S
AUDIO VIDEO
TECHNICAL
SEMINARS
D
istributor-sponsored S•T J Technical
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ALL PIONEER
LASER DISC PLAYERS
FORMER PIONEER
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