E4406A -- Cannot Open Case - Page 1
Forum section: electronics / repair

author: colorado.rob
author_rank: Frequent Contributor
timestamp: September 12, 2020, 01:10:39 am
content: I just picked up an Agilent E4406A for what I thought was a reasonable price. There are a few issues however. The most pressing issue at the moment is that I cannot get the cover off. I have removed the rear feet and 3 of the 4 screws holding the side handles on. The last screw holding the side handle, one near the front, was stuck. I finally got it to budge, but what I am left with is a screw that will turn but not unscrew.I believe what is going on is that the there is a threaded insert that was attached to the inner perforated aluminum chassis and that this is now spinning somewhat freely. I could very well be wrong about this. It is possible the threads are stripped. I can see the screw threads inside the chassis turning as I turn the screw.Has anyone experienced this issue with Agilent equipment in the past?In any event, I am looking for suggestions on how do deal with this that does not involve significant damage to the case.

author: TheMG
author_rank: Frequent Contributor
timestamp: September 12, 2020, 03:15:14 pm
content: Try sticking a flat screwdriver under the head of the screw if you can, to pry outward on the screw while you turn it. If it's just the threaded insert that's come loose, the pressure applied by pulling outward on the screw will hopefully keep the insert from spinning as you turn the screw.If that doesn't work, you might have to drill out the head of the screw. A drop of superglue can help keep it from spinning while you drill. Use a good sharp drill bit and don't apply too much downward pressure so you don't break the glue loose and cause the screw to spin.

author: bdunham7
author_rank: Super Contributor
timestamp: September 12, 2020, 03:38:38 pm
content: Are the other 3 handle screws 'captured' in the handles or did they just come out? Are they machine screws with a countersink or is there an area under the head where the threads fade away? And how loose is the screw that won't unscrew--is there any clearance or slack or is it still pretty tight? And can you tighten it back up?I haven't had that exact unit, but from a lot of experience with screws I think you may be in for a tough time. If the threads were stuck in the first place and never budged--the insert gave way instead--then the threads aren't going to start turning now no matter what you do. If it is not too loose or you can get it to tighten back up, drilling it may be the best option. Use some fresh M42 drill bits (start small), a little oil, a lot of pressure and slow speeds. Once the parts are off you can sort out what happened inside.

author: colorado.rob
author_rank: Frequent Contributor
timestamp: September 12, 2020, 06:55:01 pm
content: Thanks for the suggestions. Much appreciated.I finally managed to get it out. Apparently it was stuck behind the protrusion from the front plate. I damaged the carrying handle in the process, but at least it is open now.Addendum: apparently someone that lacked any sense of proper torque for an aluminum chassis had a go at this unit. I found one more stripped screw as I opened the unit up, and a few that were quite a bit tighter than they should be.

author: colorado.rob
author_rank: Frequent Contributor
timestamp: September 12, 2020, 10:30:41 pm
content: The next problem I am facing with this unit is that the keypad seems to be a bit wonky. Key presses are frequently missed or bounce quite a bit.I have checked that the keys are OK. They are clearly open when not pressed and they close properly when pressed. I have cleaned contacts on the PCB. I have cleaned the contacts and re-seated the ribbon cable connecting the keypad to the keypad controller board. It did not really help -- although one key that was not working at all is now working.This is not a show-stopper for me as I intend to use it via LAN/SCPI mostly.But if anyone has any ideas on what could cause this problem and how to fix it, I'd appreciate any insights.

author: zmetzing
author_rank: Contributor
timestamp: January 14, 2021, 02:40:31 am
content: Quote from: colorado.rob on September 12, 2020, 10:30:41 pmIf it makes you feel any better, my keypad is also bouncy. I also use it remotely.