Altec Lansing 9441A - Manual (Page 13)

Operating and Service Instructions for the Altec Lansing 9441A Power Amplifier
9 SERVICE INFORM­
ATION
WARNING; No user serviceable
parts inside. Extremely hazardous
voltages and currents may be en­
countered within the chassis. The
servicing information contained
within this document is only for
use by Altec iMusing authorized
warranty repair stations and
qualiped service personnel. To
avoid electric shock DO NOT per­
form any servicing other than that
contained in the Operating Instr­
uctions unless you are qualified to
do so. Otherwise, refer all servi­
cing to qualified senice personnel.
NOTICE: Modifications to Altec
Lansing products are not recom­
mended. Such modifications shall
be at the sole expense of the
pcrson(s) or company responsible,
and any damage resulting there­
from shall not be covered under
warranty or otherwise.
9.2 Equipment Needocl
To precisely adjust the
trimpots, you must have tlie fol­
lowing equipment:
1 — Digital DC volt meter
2 — 4 Cl load rated at 200
watts
1 — Small non-conducting
flat-blade screwdriver or
set of p l a s t i c T V
alignment tools
Miscellaireous handtools
(to remove the top cover)
NOTE; If you need to verify the
amplifier's performance against
the rated specipcations, you must
be able to maintain the ac line
voltage constant at 120 V ac (or
240 V ac if wired according to
Figure 2). Therefore, we recom­
mend a suitably rated variac (50
ampere rating at 120 V ac).
9.2 Adjusting VR02 and
VR102, the BIAS
Trimpot
To adjust VR02 and VR102 for
the proper bias, follow the pro­
cedures below:
1. Turn power off and dis­
connect the unit from its
power source. Make sure
the unit is in the Dual
mode with 4 D loads con­
nected to each channel.
2. Remove the ten screws se­
curing the top cover.
Refer to Figure 1 for the
.screw locations.
3. Channel 1: Locate the
junction of Ql2’s emitter
and R37. Connect the pos­
itive side of the digital DC
volt meter to the junction
of QI2’s emitter and R37.
Then locate the junction
of Ql4’s emitter and R38.
Connect the negative side
of the digital DC volt
meter to the junction of
Ql4’s emitter and R38.
Connect the unit to its
power source and turn the
power on. Adjust VR02 so
that the digital DC volt
meter reads 7 milli volts
DC (± .2 mVdc). Turn
power off and disconnect
the unit from its power
source.
Note; Adjust Bias im­
mediately
after turning
power on.
4. Channel 2: Locate the
junction of Qll2’s emitter
and R137. Connect the
positive side of the digital
DC volt meter to the
junction of Q112’s emitter
and R137. Tlien locate
the junction of Qll4’s
e m i t t e r and R138.
Connect the negative side
of the digital DC volt
meter to the junction of
Qll4’s emitter and R138.
Connect the unit to its
power source and turn the
0 .
9.7
power on. Adjust VR102
so that the digiUiI DC volt
meter reads 7 milli volts
DC (± .2 mVdc). furn
power off and disc'.'iinect
the unit from its pow'er
source.
Note:
Adjust r.ias im­
mediately after Lii ruing
power on.
Re-install the lop cover
with the ten screws pre­
viously removed.
Oi'ilex'ing Replacement
Parts
To
order replacvinent
parts, look up the
number from the componen, parts
listing and call (405) 32-5-531L,
FAX (405) 324-8981, or wrih-:
Altec I.ansing
Replacement Parts Sales
P.O. Box 26105
Oldahoma City, OK 73120-0105
9.8 Factory Service
If factory ser\ ice is
required, ship the unit ;;i its
original packing prepaid tv
Altec Lansing Customer
Service/Repair
10500 W. Reno
Oklalioma City, OK 73128
Enclose a note describing the pro­
blem in as much detail as possible.
Include any additional helpful in­
formation such as test conditions,
where used, how used, etc,
9.9 Technical Assisi anee
For applications assistance
or other technical information,
contact the Technical Services
Manager. You can call (405) 324-
5311, FAX (405) 324-8981, or
write:
Altec Lansing
Technical Services Manager
P.O. Box 26105
Oklalioma City, OK 73126-0105
ALTEC LANSING'^ CORPORATION • a Mark IV Company
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