Owner`s manual

6
A. DEAD - Won’t Power Up or Trips Fuse
1. If your Stereo 70 is simply dead (no filaments illuminated) and the fuse does
not trip - follow the steps in this section. If the fuse trips immediately, go to
section A2 below, and if the fuse trips slowly (after the amp warms up) go to
section A3 below.
a. Insure that you actually have power at the plug (try a lamp or another
component connected to the same receptacle).
b. Is the power switch in the ON position ?
c. With you Digital Voltmeter set to the AC Volts
function, measure the voltage at
the two black leads of the power transformer. The voltage should be
approximately 110VAC across these two leads.
2. If the fuse trips immediately continue following the steps outlined in this
section. If the fuse trips immediately, proceed to section 3 below.
When the fuse trips immediately the problem is most likely in the power supply
section. The good news is that there are only a few components that comprise the
power supply and fewer still that have a high probability to be defective. The bad
news is that failures can be slightly catastrophic causing several parts to be
sacrificed in a domino fashion. The technique described below will guide you in
identifying any defective component. Note - You are about to open up your
amplifier and expose yourself to potentially lethal voltages. Please be aware of
this and for safety sake always assume that lethal voltages are present and follow
the steps outlined accordingly. When indicated in the text, it is imperative that
you follow the Quad Electrolytic Capacitor Discharge Procedure outlined
below.
QUAD ELECTROLYTIC DISCHARGE PROCEDURE
Get two of your jumper wires with alligator clips and the 100 ohm resistor. Clip
one end of one of the clip leads to the chassis; connect the other end to the 100
ohm resistor. Connect one end of the other clip lead to the remaining lead of the
100 ohm resistor. Connect the remaining end of the second clip lead to the metal
shaft of your screwdriver. For about 10 seconds each, touch each leg of every
section of the Quad Electrolytic capacitor with the blade of the screwdriver. There
are four sections each protruding from the insulating center section of the
capacitor. Then repeat this step again. You are basically discharging each
capacitor thru the resistor until each has fully discharged.