Agilent 34401A button repair

[buck converter]

I have some 34401A and they all have issues with the button pads. A lot of the buttons, especially the shift needs a lot of pressure to activate. Is there a best practice for repairing this?
Thank you in advance.

[robert.rozee]

disconnect the ribbon cable to, then carefully remove, the front panel. disassemble PCB from the rest, and (gently) clean both the conductive rubber button pad contacts as well as the PCB contacts with IPA or similar, then see if there is an improvement. i'd be a little surprised if the conductive rubber had deteriorated, but others may be able to comment further on that.


cheers,
rob   :-)

[coromonadalix]

https://www.ebay.com/itm/362513186617?

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[NoisyBoy]

I second Robert's suggestion.  If it doesn't work, perhaps some Caikote 44 may work if you don't want to change out your keypad. 

While you have the keypad out, it is also a good time to clean the sides and the part behind the front panel, as well as the openings around each key on the panel.  It can make your 34401a keypad look new again.

Good luck.

[buck converter]

I have attempted repair on one of my units so far. I rubbed IPA all over the pcb and button membrane, twice. It improved most buttons, leaving just one that needs to be jammed in to activate.
Is there a different chemical that performs better? I have a few more units with the same issue. These are from a classroom lab and saw daily use from multiple sections a day for who knows how many years.

[GigaJoe]

not really chemical, rubber is conductive, need to restore conductivity, i use a soft b2 b3  pencil on membrane keyboards button. guess it the same way. 

[floobydust]

The SHIFT button doesn't get pressed so much so I suspect dirt, not wear.

With the 34401A, I take them right apart and the keypad out and clean GENTLY dish soapy water, use an old toothbrush and rinse.
There's everything from hair to component lead clippings inside. The silicone keypad does tear apart easily so it's not easy to work on.
Next I use IPA and Q-tips to clean the PC board. It doesn't have carbon print.

I've tried various methods to repair keypads. I would just order the remote control/conductive rubber pads kit. That's the best IF the pads are worn out.
https://www.eevblog.com/forum/repair/carbon-contact-pad-repair/msg4032652/#msg4032652
https://www.eevblog.com/forum/repair/best-method-to-restore-conductive-keypads/