HP/Agilent E3615A Power Supply experience - erratic display

[n6rob]

I am posting my experience so others may benefit from what I learned about repairing this power supply.

I found this post in my research and found it helpful:  https://www.eevblog.com/forum/testgear/hpagilent-e3615a/.  In the last message of the topic the author notes that the "OVP/CC Set" button (S7, a & b on the schematic) on the face becomes erratic and makes the unit "weird" (a very technical term... ).

I recently bought one of these units listed on eBay as "for parts/not working".  Indeed, the unit was acting "weird" when I powered it on. 

The power supply was delivering rated voltages and current to the terminal posts as measured with a separate DMM.  Adjustments worked and the output was steady, over-time.  However, the display was erratic - wandering all over the place.  I also notice when I pushed the OVP/CC button rapidly the display would wander even more... hmmm... I cleaned the switch with contact clearer, worked it a couple dozen times, and the display works as intended.  I would have preferred to disassemble the switch to clean it more thoroughly, but I wasn't sure I could get it apart without a risk of destroying it.

On another note, the plastic in these old units gets really brittle.  Holy cow!  I ended up with a pile of small broken plastic bits, mostly from the display "shell" that goes on the front of the unit.  I'll probably have to hot glue the display PCB into the housing as all the plastic retainers are gone.  Ugh. 

But as others have said, these supplies are second-to-none in quality and performance.  Love 'em.

Good luck with yours!

[zrq]

The front panel switch is a common problem with many different HPAK E36xx power supplies. Almost all of them in my day job lab have gone half bad.