Hello,
We have a E4440A that has started failing the Align All sequence when powered on. The error is Calibration Failed, Align_RF_Gain_Preamp. The associated code for this failure is -340. Additionally, since this fails, the Systems, Alignments, Align all now, Needed is displayed.
I have checked signals according to the service manual and can't seem to find anything wrong with the unit. Plus the battery has been changed. The service manual states this error could be caused by a number of issues. The unit is also now trying to perform the Align All Now approximately every five minutes This unit is only five years old. Has anyone seen this problem and if so what seemed to be the cause and/or fix?
We have a E4440A that has started failing the Align All sequence when powered on. The error is Calibration Failed, Align_RF_Gain_Preamp. The associated code for this failure is -340. Additionally, since this fails, the Systems, Alignments, Align all now, Needed is displayed.
I have checked signals according to the service manual and can't seem to find anything wrong with the unit. Plus the battery has been changed. The service manual states this error could be caused by a number of issues. The unit is also now trying to perform the Align All Now approximately every five minutes This unit is only five years old. Has anyone seen this problem and if so what seemed to be the cause and/or fix?
The error is telling you that it there is a signal level problem when checking the preamplifier option hardware (1DS if lowband, or 110 if broadband).
What typically happens on older vintage 1DS assemblies is intermittent poor contacts on the two relays that switch the preamplifier circuit in and out of circuit.
The self-align routine exercises the preamp switches, but it does so quite quickly, and any sluggish switching or amplitude drop-out will result in an align failure, even though the static amplitude may appear reasonable if viewed manually.
To check for this, try cycling the preamplifier On and Off whilst monitoring the internal 50 MHz calibrator signal:
Preset
Frequency, Center Freq 50 MHz
Input/Output, Input Port, Amptd Ref (f=50MHz)
Span 1 MHz
Amplitude, Ref Level -23 dBm
Amplitude, Scal/Div 1 dB
Amplitude, Res BW 300 kHz
Amplitude, Attenuation 20 dB
Peak Search
You should see the top of the 50 MHz calibrator signal at center screen, two divisions down from the top, with a marker on the peak.
Note marker amplitude: it should read -25.00 dBm, give or take about 0.05 dB.
Now press:
Amplitude, More, Int Preamp On/Off
Keep pressing this third softkey to toggle the preamp On and Off, whilst observing the marker level, which should remain at around -25.00 dBm.
While switching, you should hear the faint click of the 1DS mechanical relays switching in and out, and notice the "PA" display annunciator appear lower left of display when preamp is On.
Switch it several times, and watch for any brief drop in amplitude of more than half a dB, which would indicate intermittent switches, requiring preamplifier assembly replacement.
Note the amplitude may not be exactly the same between preamp on and off (allow maybe 0.3 dB max), but should be stable in both settings.
If you switch it 500 times, and don't see any drop-outs, chances are the preamp switches are stable.
Typically bad preamp switches will show intermittent amplitude losses of several dB or more, getting worse with age.
This is assuming the Preamp error is the only (or primary) error reported. Check the whole error queue by pressing: [System], [Show Errors].
There may be another more major amplitude problem elsewhere in the RF section that is causing the preamp to fail.
Try exercising the RF Input Attenuators in a similar way to above, and also the option B7J Electronic Attenuator, if fitted (toggle between SA and BASIC mode to switch E-Atten in and out of circuit).
I hope this helps,
Cheers, Simon C.