Author Topic: Agilent/Keysight N9310A repair hints solicited  (Read 893 times)

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Offline bernroth

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Agilent/Keysight N9310A repair hints solicited
« on: January 21, 2018, 12:46:02 pm »
Hello folks!

I have a Keysight N9310A on my bench which needs to be repaired. It powers on normally, passes all self tests.
It is a unit from 2008 so a bit aged.

Problem: Some buttons are not working (e.g. "RF on") and the "Information" screen, which should normally show firmware version, options etc., has black pixels all around and misplaced fonts.
I will post a screenshot tomorrow. It looks quite funny.

All other screens and menus I tested are showing correctly.

I have checked all supply rails with DMM & scope (glitches). Nothing unusual, all voltages are there.
The caps in the PSU show no signs of bulging.

When probing the keyboard flat flex connection to the board, most buttons show sharp transitions high/low when pressing.
Except the RF button (and others in the row like "Trigger"):
When pressing, the "edges" are like the curve of a charging capacitor (RC), very slow.

I suspect two things:

First: Possibly the keyboard, inparticular the RF-ON button has a bad contact or is dirty. This could be the button which is used most.
Second: The weird pixels and misplaced fonts all over the place in the "Information" screen might be due to bad memory maybe or a bad regulator on the digital board.

Maybe someone has a similar issue in the past :)

I keep you posted, thank you!

Cheers,
Bernhard



 

Offline Samogon

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Re: Agilent/Keysight N9310A repair hints solicited
« Reply #1 on: January 21, 2018, 06:28:47 pm »
For the button i would check multiplexer. As for the artifacts on the oarticular screen points to the firmware corruption
 

Offline bernroth

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Re: Agilent/Keysight N9310A repair hints solicited
« Reply #2 on: January 22, 2018, 05:41:01 am »
Update:

Attached the broken "information" screen.
I cleaned the keyboard but no change for RF-button.
Only once removing and re-inserting the CPU board helped to make the RF-Button work again.
Maybe there was a bad contact. Strange... all gold plated contacts. Hmm.

The only and last non-working button is "Trigger". Possibly inactive due to missing license?

I took apart the CPU board and found an empy BR2032 battery (BR... looks to be the industrial battery type with an extended temperature range and longer shelf life)

But what I've found: Micron memory dated week 54 2005
I had in the past dead Cisco Switches with failing memory (guess what: Micron :palm:)

I wonder if the power on self-test should detect bad memory.
The information screen let me think the memory being bad.

Voltages (1.8 + 3.3V) on the CPU board are fine.

I will continue searching :)

« Last Edit: January 22, 2018, 05:58:29 am by bernroth »
 

Offline Samogon

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Re: Agilent/Keysight N9310A repair hints solicited
« Reply #3 on: January 22, 2018, 03:52:09 pm »
Well self test may check checksum of firmware and should flag it as bad.

Try to update firmware it wont hurt.
« Last Edit: January 22, 2018, 03:54:27 pm by Samogon »
 

Offline bernroth

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Re: Agilent/Keysight N9310A repair hints solicited
« Reply #4 on: January 24, 2018, 07:28:06 pm »
A firmware update was performed successfully but the error is still present.
I suspect the memory (Micron - see other post) and I ordered some replacement parts.
I keep you guys posted.
 


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