Crown k1 Manual Suplementario

K Series Service Manual

Rev A.

5-6  Maintenance

©1999 Crown International, Inc.

As mentioned earlier, the three steps to effective re-
pair are: Determine the symptoms; identify the cause
of the symptoms; repair the unit to eliminate the cause.

The purpose of this section is to help you through these
steps in an orderly manner.

5.3.1  Identifying Symptoms
Why was the amplifier brought in for repair? Can you
get it to malfunction again? Some problems can be
intermittent and difficult to find.

Once you have identified and verified the symptoms,
you can look for helpful information in Section 5.3.2 as
to where the cause of the problem is located.

If you don’t observe anything wrong with the amplifier,
tactfully inquire how the owner used it and try to deter-
mine if it was misused or some other component in
their system could have been at fault. Remember that
the protection circuits in this amplifier will protect loud-
speakers from problems caused upstream from the
amplifier (DC protect).

If you lack sufficient information about the problem,
and there aren’t any obvious problems with the ampli-
fier, skip to Section 5.4, the Electrical Checkout Proce-
dures.

5.3.2  Identifying and Repairing the Cause
The first step in identifying the cause of the problem is
always a visual inspection. Once the bottom cover is
removed, and the supplies are discharged, look for
loose connectors, broken wires, loose hardware, burnt
components, or bad solder joints on the PC boards.
Any burnt components are a sure sign that the PWA
will need to be replaced.

Once the visual inspection is complete you may pro-
ceed in powering up the unit. The best way to posi-
tively locate which PWA is at fault is to have a working
PWA of each type on hand and plug them into the
amplifier one at a time to see when the problem goes
away. Output and Input PWAs can be plugged into the
amplifier easily without removing the old PWA. When
doing so, use an insulating material to isolate it from
the chassis and other PWAs. The Main PWA, however,
needs to be installed into the chassis before it can be
properly hooked up.

The following Symptoms and Causes may help you
determine which corrective action to take. We realize
that this list is limited. Please read through the Theory
chapter in this manual to better understand the func-
tion of each PWA. This will help you come to your own
conclusion as to the location of the problem.

Amp does not appear to power up. No Enable light.
First, check the power supply fuse. Also, make sure
the AC line voltage is correct for the amplifier you are
working on. Severely low AC line voltage could cause
the amp to not power up. If both check out, then the
amplifier is in a fault mode. The two most likely areas
are the Main PWA or an Output PWA.

First, check the Output PWAs. 

, then disconnect the main wiring harness (P3)

from the PWA in question. Now power up the unit. Af-
ter the delay, if the enable light comes on, the discon-
nected Output PWA needs to be repaired or replaced.

To check if the Main PWA is at fault 

, then unplug only one Output PWA from the

main wiring harness (P3), and unplug the Input PWA
(P2) from the Main PWA. Now apply power and check
the +15VDC and the -13VDC. To do this, locate U7 on
the Main PWA (next to where the Input PWA overlaps