Electronics > Repair

Agilent 34461A display failure......suggestions please!

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300DT:
Hello!

My 34461A meter screen is working, but freezing when it initiates.

It comes up with the Agilent Technologies screen and a black scroll bar (all in black and white, not colour). Then the screen info disappears and  goes dark.

No amount of button pushing will get it going unless you cycle the power switch and the same thing happens over and over on each recycle-button-push.

All voltages check out OK as per the "trouble shooting" section of the manual.

I have checked all the frequency generating sources and they are all ok except for one 25MHz crystal that is 2K low in frequency.(not probably a problem)

This has me baffled and I am considering a "reball" of the bga chips, but am looking for any suggestions first. I'd be happy with just a schematic to get things going!!!!

Thank You!

Mike

LA7SJA:
If it's out of warranty then try;

1.) Is it on a network?
2.) If so, can you ping it?
3.) If you can ping it, you could try a "remote" firmware upgrade with the "Keysight Firmware Update Utility" select LAN(Socket) IP address.

Johan-Fredrik

300DT:
Hello Johan-Fredrik!

Thank you for the suggestion. My meter however is freestanding and is not on a network and has never been hooked up to one.

I suspect that it does not even initiate itself.

The display board has 3 BGA chips and one small CPU on it that may have failed and are suspect.

Without a schematic I can just generalize and look at the function of most of the chips.

Dave's 34461A disassembly video is very helpful in this regard.

Thank You!

mb 

HighVoltage:
If it is only the display that is not working, you should be able to connect with the Keysight I/O Library through the network adapter, as long as it is set to obtain an IP address automatically.
Also, it is might be helpful to get a GPIB adapter and connect that way.

How old is the DMM?
Did something happen, that caused this problem, as far as you know?

wraper:
First of all this is not "display failure" but failure to boot.

--- Quote ---This has me baffled and I am considering a "reball" of the bga chips
--- End quote ---
More and more I tend to think that people should be publicly prosecuted for such suggestions.
Return it under warranty, it has 3 years. Your chancet to repair it by soldering, replacing some part, are rather slim IMO. Very likely this is NAND corrupted.

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