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2. Measure the voltage on the actual terminal from the front of the
front panel board, not at the circuit board of R17. [READING =
5.4VDC] If not correct go to step 3 otherwise re-solder the
connection on R17.
3. While adjusting R17 measure the voltage on the center
connection of R17. [READING varies between 0 and 5.4VDC]
If correct measure the voltage on U3 pin 4 while adjusting R17.
[READING varies between 0 and 5.4VDC] Otherwise check for
opens, shorts and incorrect component installation, C6, C15,
C21, R5 and R17 and connected circuit paths or U3 may be
defective.
Problem:
Checks:
1. Measure the voltage on U3 pin 17, [READING = 5.4VDC] If
correct go to step 2, otherwise go to the "Improper operation of
bass, treble, balance, loudness and volume controls"
troubleshooting section.
2. Measure the voltage on the actual terminal from the front of the
front panel board, not at the circuit board of R19. [READING =
5.4VDC] If not correct go to step 3 otherwise re-solder the
connection on R19.
3. While adjusting R19 measure the voltage on the center
connection of R19. [READING varies between 0 and 5.4VDC]
If correct measure the voltage on U3 pin 9 while adjusting R19.
[READING varies between 0 and 5.4VDC] Otherwise check for
opens, shorts and incorrect component installation, C8, R8 and
R19 and connected circuit paths or U3 may be defective.
Problem:
Checks:
1. Measure the voltage on U3 pin 17, [READING = 5.4VDC] If
correct go to step 2, otherwise go to the "Improper operation of
bass, treble, balance, loudness and volume controls"
troubleshooting section.
2. Measure the voltage on the actual terminal from the front of the
front panel board, not at the circuit board of R20. [READING =
5.4VDC] If not correct go to step 3 otherwise re-solder the
connection on R20.
3. While adjusting R20 measure the voltage on the center
connection of R20. [READING varies between 0 and 5.4VDC]
If correct measure the voltage on U3 pin 12 while adjusting R20.
Balance control only not functioning properly
Volume control only not functioning properly
UAM4SYS • 33
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