Hi we have several 34401A's which were working fine prior to being put into (climate controlled) storage for 18 months or so. On retrieving the units and testing them, it was found that a number of them failed to power up correctly. They all follow the same sequnce which is:
Power button is pressed, display comes on for about one second, display goes off, unit emits one beep of about one seconds duration, display stay off and there is no response to any buttons apart from the "shift" key, which lights the "shift" legend on the display. It is not possible to run the self test or do anything with the unit. when it is powered off, the display flicks on for a second or so and goes off. We have about 8 of these instruments of various ages, all doing the same. I can find no service note or any reference to this behaviour anywhere within Keysight's web pages, although there are some references on the web. One person alleges this was fixed on his unit by wholesale re-soldering around the ground-referenced components in the rear of the unit, but I don't believe we have multiple units with dry joints....
Can anyone suggest a cause or remedy?