Sencore PA81 Tech Tips

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Means Success In Electronic Servicing
The PA81 STEREO POWER AMPLIFIER
ANALYZER provides the ability to analyze and
isolate defective stages in audio equipment. Its
three inputs provide the ability to test the output
of audio equipment ranging from phono pickup
cartridges to large power amplifiers. This TECH
TIP will familiarize you with the PA81 and its
features. It is broken into 4 major sections:
1) Inputs
2) Measurement functions
3) Using standard test signals
4) IHF Filters
Inputs
The PA81 has 3 different inputs - Dummy Load,
Line, and External. Each is optimized for a
specific use in a different portion of an audio
system. Since the PA81 is stereo, each input
Learning To Use The PA81
has a left and right channel. Which input is
connected to the measuring circuits is deter-
mined by the setting of the FUNCTION switch.
This section explains the basic application of
each input. The next section explains the indi-
vidual measurement functions.
DUMMY LOAD Input
The IHF DUMMY LOAD inputs allow you to
performance test and check the operation of
power amplifiers at their rated power. The
DUMMY LOAD INPUTS replace the system
speakers, and provide accurate measurements
and proper load impedances. The black ground
banana jacks are isolated from each other, and
from the other inputs, to allow testing amplifiers
that do not have common grounds.
STEREO POWER AMPLIFIER
ANALYZER
The orange color coded portion of the FUNC-
TION switch selects measurements through
the DUMMY LOAD input. The RMS WATTS
function is unique to this input. Two other fea-
tures also work only in conjunction with the
DUMMY LOAD input- the IHF DUMMY LOADS
switch, and DC BALANCE. (Refer to figure 1)
IHF DUMMY LOADS Switch
The IHF DUMMY LOADS switch allows you to
select the necessary impedance to test the am-
plifier under the specified load condition. The
switch selects the impedance for both the left
and right channel simultaneously. To connect to
the amplifier, set the IHF DUMMY LOADS switch
to the same impedance that is specified for the
speakersandconnectthe PA81 's DUMMY LOAD
input in place of the speakers.
PA81
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Fig. 1: DUMMY LOAD Inputs, DC BALANCE SWITCH, and IHF DUMMY LOADS work together to performance test power amplifiers.
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