5-Volt/3 Amp Power  (277-0119)     Troubleshooting     Faxback Doc. # 15759
Supply

A troubleshooting chart is provided, however, it lists only the most
obvious trouble conditions.  Before replacing parts, check your work.  Poor
solder joints, solder bridges, incorrect wiring and incorrect parts
location are the most common causes of trouble.  The theory portion of this
manual should help you better understand the circuits and help you locate
troubles.  Use your schematic diagram to determine usable test points.  For
resistance and continuity measurements, ensure that power is removed from
the unit.

TROUBLESHOOTING CHART

CONDITIONS                             POSSIBLE CAUSE

No output Voltage                      Input power connection Switch S1,
                                       Fuse 1 or F2.  Adjustment of
                                       foldback potentiometer.  Pass
                                       element.  Short circuit resistor.
                                       Open sense line and diode.

Output Voltage Exceeds                 Zener diode VR1.  Amplifier
6.5 Volts                              transistor Q2.  CR2.

Erratic Output                         Load connections.  Sense leads and
                                       connections.  Protection elements-
                                       diodes, resistor, capacitors.

Output Voltage High but                Sense leads and connections.  Sense
less than 6.5 Volts                    diodes.  R3 not adjusted
                                       correctly.

Output Voltage OK with                 QI wiring.
no load but goes low with
load applied.


(br/all-06/28/95)