HP 5384A - Page 145

HP 5384A and HP 5385A
Service
A 1 U4t3! 0.01 /JS/div.
A1U5A i 2~ 0.02 ,us/div.
0.1V/div. ac coupled 0.5V/div. ac coupled
de level is approximately 3.6V de level is approximately 3.8V
A 1U6(
11 l 0.02 J.LS/div.
0.2V/div. ac coupled
de level is approximately 2.8V
figure 8-46. HP 5384A Channel B Waveforms (Continued)
8-300. To troubleshoot the HP 538SA Channel B
input amplifier, first check for a blown INPUT fuse.
Refer to figure 2-5. If the fuse is blown, replace it and
apply a 100 MHz signal at 25 mY rms (70 mV p-to-p) to
the Channel B input BNC. Press the FREQ B key.
Referring to figure 5-3, check that the proper wave-
form exists at A 1 U6A i11 ). If the proper signa I is not
present, probe the followig list of nodes. ( Follow the
sequence shown in the list or or use the half-splitting
technique and begin with A 1U19(10).) Refer to Figure
B-47, HP 5385A Channel B Waveforms, for the proper
signal you should observe at each node.
CIRCUIT NODE
A1CR25 icathode)
A 1 L
10 (lead nearest
front panel )
A1L12 (lead nearest
front panel)
A1U19i101
A1U19(4)
A1U6At111
CIRCUITRY
Channel B limiter output
Channel B 1st gain stage output
Channel B 2nd gain stage output
Channel B divide-by-256
frequency divider input
Channel B divide-by-256
frequency divider output
Channel B to MRC output
8-39