User's Manual

44
Outputs:
NODE ( + ) EXTERNAL SUPPLY MEASUREMENT
A5C3 (+) ON/OFF 10Vdc
A5VR1(K) ON/OFF 6.5Vdc
A5U1-3 ON/OFF 0.2Vdc
A5CR2(K) OFF 1.8Vdc
A5CR2(K) ON 0.2Vdc
A5U1-1 OFF 0.5Vdc
A5U1-1 ON 5.0Vdc
+R20 OFF <0.001Vdc
+R20 ON 1.5Vdc
NODE ( - ) = A2J7-4
Troubleshooting CV Circuit
V-MON, the output of CV Monitor Amp A2U2, is 1/40 (1/4, 6011A, 6012B) the voltage between + S and - S. CV Error
Amp A2U3 compares V-MON to CV PROGRAM. Innerloop Amp A2U5A stabilizes the CV loop with input from A2U5B.
The measurements below verify that the operational amplifier circuits provide expected positive and negative dc voltage
excursion when the CV loop is open and the power mesh shut down.
Circuits Included. Constant Voltage (CV) Circuit and buffer amplifier A2U5B.
Setup. The Main Troubleshooting Setup, page 33. Apply the ac mains voltage to the isolation transformer, and disconnect
the external supply Remove the + S jumper and connect A2J7-2 ( + 15V) to + S. Set mode switch settings B4, B5 and B6
all to 0. Set VP to 0Vdc by connecting to
P or set VP to + 5Vdc by connecting to A2J7-24 according to SETUP below.
VP and
P are on rear-panel terminal block.
Outputs:
NODE ( + ) NODE ( - ) SETUP MEASUREMENT
VM A2J7-4 3.75Vdc
A2U5-1 A2J7-4 VP = 0 -14Vdc
A2U3-6 A2J7-4 VP = 0 -14Vdc
A2U5-1 A2J7-4 VP = 5 13Vdc
4.7Vdc (6011A, 6012B, 6015A)
A2U3-6 A2J7-4 VP = 5
≈ 0Vdc
5.1Vdc (6011A, 6012B, 6015A)
A2U5-7 A2J7-4 short A2J7-24 to A2U5-5 + 7.5Vdc
If the failure symptoms include output voltage oscillation, check if the CV Error Amp circuit is at fault by shorting A2U3-6
to A2U3-2. If oscillations stop, the CV Error Amp circuit is probably at fault.
Troubleshooting CC Circuit
I-MON, the output of CC Monitor Amp A2U1, in volts is ≈ 1/3 (1/24, 6011A) the output current in amperes. CC Error
Amp A2U4C compares I-MON to CC PROGRAM. Differentiator circuit A2U4A differentiates the inboard voltage sense
to stabilize the CC loop. Its output is summed with I-MON at CC Error Amp A2U4C.
The measurements below verify that the operational amplifier circuits provide expected positive and negative do voltage
gain when the CC loop is open and the power mesh shut down.