Fluke 5500A, Service Manual

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5500A
Service Manual
6-118
11801B Setup
Voltage/division 10 mV/div
dc offset Centered
Dot Response Centered
Smooth On
Time Base Position 5
µ
s
Time/division 0.5
µ
s
Trigger Level Center, negative slope
Trigger Input x10
External Trigger 1 M
Ω
Sequential On
Scan Repetitive On
6-152. Adjusting the Edge Aberrations for Board 5500A-4004-1
Follow this procedure only if you have Board 5500A-4004-1 (Fluke PN 600749).
1. Adjust the dc offset on the 11801B so the last 500 ns of the peak of the square wave
is on the center line.
2. Change the time/div on the 11801B to 20 ns/div.
3. Slowly adjust pot R168 and observe its effect on the waveform. the left half of the
wave peak will move up and down as you turn R168. Adjust R168 until the center of
the wave peak is half of a division above the center line, as shown in Figure 6-33.
4. Change the time/div on the 11801B to 5 ns/div.
5. Slowly adjust R57. It will affect the first 50 ns of the wave form. Adjust R57 so the
rising edge falls back and crosses the horizontal center line one division before the
vertical center. Refer to Figure 6-34. The base of the aberration should be 10 ns
apart.
6. Change the time/div on the 11801B to 2 ns/div.
7. Adjust R16 until the rising edge ledge reaches the center line. Refer to Figure 6-35.
8. Return to 5 ns/div and verify that the pattern shown in Figure 6-34 still exists.
Repeat the adjustment in step 5 if necessary.
9. At this point in the adjustment, each graticule line on the oscilloscope represents a
1% aberration. Typically this board shows aberrations of 0.5% within the first 10 ns,
and aberrations of 0.25% during the following 10-30 ns.