Agilent E4419B - Investigation

[@feedback-loop]

disconnect the keypad altogether before you try bridging contacts on the board

[@tgsoapbox]

Thanks - I wouldn't have thought that this would make a difference as the button should be in parallel to the short but it certainly appears to. Looks like I'll need to disassemble the front panel - Did you have any success in cleaning the keypad?

[@tgsoapbox]

I just checked eBay and they have replacement membrane keypads for around US$25 - I've never had much luck cleaning them but it'll be interesting to see if it is possible.

[@feedback-loop]

​@@tgsoapbox I believe that they fail by developing internal shorts between layers

[@davidv1289]

In addition to feedback loop's suggestion, I would also check the ripple on the power rails. The + 12 V rail is a bit suspect. Regards, David

[@tgsoapbox]

Good reminder - I should compare both units just to see how the PS is going on the 19B

[@amirb715]

it's the membrane keypad and the only solution is to replace it. been there done that several times. was never successful in repairing that keypad membrane.

[@tgsoapbox]

Thanks - I have never been successful either but I watched FeedbackLoop's video where his magically started working so who knows :)