Field Modifications; Timing/Mute Capacitors - Crown CE-1000A Service Manual

Rev. D

9 Field Modifications

This section details field modifications authorized and
recommended by Crown which should be performed
on affected units. Only the specific models identi-
fied in each case should be modified. If you are in
doubt whether the amplifier you are servicing needs
any of the modifications described in this section,
contact the Crown Technical Support Group.
PLEASE HEED ALL CAUTIONS AND WARNINGS.
Crown Authorized Warranty Centers should refer to
their " Tech Notes " library for up-to-date field modifi-
cation instructions.
NOTE: THE INFORMATION IN THIS MANUAL IS IN-
TENDED FOR USE BY AN EXPERIENCED TECH-
NICIAN ONLY!
9.1 Fan Circuit Ballast Resistors
Applicability: CE1000, CE2000 Models, with –6 mod-
ules, built in January 1998.
When servicing a CE1000 or CE2000 amplifier, the
resistors R14 and R15 should be checked for the
correct value part. These resistors should be a 0.2
ohm (A11371-0R21), but it is possible they may be a
zero ohm jumper due to a manufacturing error. These
resistors are part of the fan circuitry. They are the
ballast resistors for the darlington transistors Q1 and
Q2.
The amplifier will not exhibit any abnormal perfor-
mance due to this change in resistors. However, if
you have a CE amplifier on the bench, verify that R14
and R15 have the proper value resistor. If it has the
zero ohm jumper, replace it with the above specified
0.2 ohm resistor.

9.2 Timing/Mute Capacitors

Applicability: CE-1000 and UT-1010 with #102138-8
modules, and CE-2000 and UT-2020 with #102140-8
modules.
Some early model CE amplifiers may not come out of
standby upon start up. When this happens, the fault
light will simply continue to flash on and off indicating
that there is some fault condition on the amplifier. It is
likely that the problem may be the formation of con-
CE Series Service Manual
densation under the timing capacitors & resistors,
C121/221 & R174/274 and/or the muting capacitors
& resistors C124/224 & R192/292. Additionally, resis-
tors R6 and R18 need to be upgraded to a new value,
and resistor R29 should be removed.
This problem has only occured on 102138-8(CE1000)
and 102140-8(CE2000) boards and earlier, (before No-
vember 1998). Newer revision main modules (i.e.
102138-9(CE1000) / 102140-9(CE2000) and later) will
not have this problem because the timing circuit was
changed to be lower impedance and utilize an elec-
trolytic capacitor for timing.
Procedure:
1. Upgrade R6 to 9.31 kohm 1% (CPN A11368-93111)
and R18 to 7.15 kohm 1% (CPN A11368-71511).
2. De-solder and remove R29. This circuit location will
remain open.
3. De-solder and remove the muting capacitors and
resistors.
4. Thoroughly remove all residual adhesive from un-
der the removed components. Caution: Any remain-
ing adhesive may act to absorb moisture and re-
peat the above-described symptoms.
5. Clean the affected area. This should be done using
only a soft bristle brush and a high grade IPA isopro-
pyl alcohol. Using anything else can result in dam-
age to the circuit board and components. After the mod-
ule is clean, it must be allowed sufficient time to dry
out. If necessary, a hair dryer (on low heat) or air gun
(low psi) may be used to assist in the drying process.
6. Replace removed muting capacitors and resistors
with new components: C121/221 and C124/224, CPN
C 6802-0; R174/274 and R192/292 CPN A11371-4751.
If there are further questions, please contact the Tech-
nical Support Group at 1-800-342-6939
Field Modifications 9-1