UAM4SYS
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cover of the manual.
Note in the following steps all VOLTAGE and RESISTANCE measurements
are taken with the RED or “+” lead of the meter connected to the indicated test
point. The BLACK lead or the terminal labeled “-“ or “common” of the
voltmeter is connected to the outside (ground) bracket on J8. The expected
reading is indicated in the “[READING = rrr]” text after the instruction to make
the reading
POWER SUPPLY PROBLEMS
Problem:
No 12 to 18 Volts Input
Checks:
1. With S1 turned off, measure the voltage at the connection on
the back of J5, (that’s the terminal on the back of the connector
itself on the top of the board). [READING = +12 to +18VDC
depending on the power supply]
If the voltage does not equal the rated power supply output or is
not present check for shorts on the circuit board between J5 and
the connection to S1
Problem:
No +10 Volts out of VR1
Checks: 1.First perform the “No 12 to 18 Volts Input” procedure. Once the
input voltage is verified to be good go to step 2.
2. Measure the voltage on U1 pin 4. [READING = +10VDC +/-
0.2VDC] If good go to step 3. If bad check VR1’s soldering.
3.If you still don’t have 10VDC check VR1’s output resistance. If
close to 0 ohms check for shorts on all of the 10V foil runs on the
circuit board. If the resistance is higher than 5 ohms but less than
5k ohms check IC orientations.
Problem:
No +5 Volts out of VR2
Checks: 1. Check VR2’s input pin for 10 volts. If good go to step 2. If bad
check VR2’s soldering and also see the “No +10 Volts out of VR1”
problem troubleshooting step, otherwise go to step 2.
2.Check VR2’s output resistance, if it is close to 0 ohms check for
shorts on all of the 5V foil runs on the circuit board. If the
resistance is higher than 5 ohms but less than 5k ohms check IC
orientations.
