Fixed: Brand new Keysight E3649A PSU, Repair and Teardown - Page 1
Forum section: electronics / repair

author: HighVoltage
author_rank: Super Contributor
timestamp: July 25, 2015, 10:45:36 am
content: I just bought this great brand new (June 2015) Keysight branded E3649A PSU from our friend TopLoser, in broken but partially working state. It was sold as damaged, the voltage output read correct but the current on output 2 was off by more than 10%.Well, this PSU was dropped, presumably during shipping, the front display cover broke in pieces, the encoder came apart and a binding post was broken, which cause the one leg of the binding post to break off. This was the reason, why the voltage read correct but the current had to flow through the sense wire only.Interesting fact: They added a 100 nF capacitor at the binding post connection to the PCB and another 100 nF to the sense wire connection on the same binding post, like 15 mm away. That is some attention to detail.Now I want to restore this great PSU to its original and new state with original Keysight parts. I will order all the parts from Keysight next week and then install them and post the progress here.I thought that may be some of you are interested in the repair, so I will post the pictures here and at the end I will do a documentation on the testing of the PSU.Enjoy!The first picture is of the web, so you know, what it is suppose to look likeThe broken binding post will be replaced with an original oneKeysight part number:E3640-60019,

author: HighVoltage
author_rank: Super Contributor
timestamp: July 25, 2015, 10:47:42 am
content: Here is a picture of the display and the broken encoderThe encoder will also be replaced by an original Keysight part.Hopefully the Display cover can be ordered, I can not find any reference on the Keysight parts website.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 25, 2015, 11:03:14 am
content: The front plastic frame was split where the encoder is screwed in with a washer and nut. I fixed it with some really awesome glue for this type of plastic. This glue is meant for Acrylic (Plexiglas) welding and is as liquid as water and works extremely well on plastics for test instruments, because it is welding the parts together and is not leaving any residue.

author: VK5RC
author_rank: Unknown
timestamp: July 25, 2015, 11:28:51 am
content: @HighVoltage I hope you don't mind but some months ago I started a list of good mechanical repairs of gear, I will list this one in it. Some excellent ideas of others you might find helpful.https://www.eevblog.com/forum/repair/vintageclassic-renovation-techniques/Please keep us updated as you repair, I find it interesting.Thanks Robert

author: TopLoser
author_rank: Unknown
timestamp: July 25, 2015, 11:37:21 am
content: Wow, awesome repair of the plastic. I never realised just how hard this thing had been hit. It didn't even rattle!

author: HighVoltage
author_rank: Super Contributor
timestamp: July 25, 2015, 12:07:05 pm
content: Quote from: VK5RC on July 25, 2015, 11:28:51 amOf course, these are for sharing in the community.I had not seen your list, thanks.Quote from: TopLoser on July 25, 2015, 11:37:21 amWell, this is built to last, just great quality on a mechanical and electrical level.May be with an exception to the encoder, they like to break on all Aglilent / Keysight gear and may be I should order 10 of them right away.Here are some more teardown pictures of the rest of the Unit.

author: robrenz
author_rank: Super Contributor
timestamp: July 25, 2015, 02:21:59 pm
content: Very nice job!I am very surprised that the binding post designer left a dead sharp shoulder where it broke off. That is a huge stress riser especially in brass. A decent radius in that corner would surely have prevented that break.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 25, 2015, 06:47:51 pm
content: Quote from: robrenz on July 25, 2015, 02:21:59 pmThank you robrenz!Very true wit the radius instead of the sharp edge on that shoulder.That reminds me, I should use the nice IET LOM 510A MICRO OHMMETER from you to measure the resistance of the binding post legs. It is astonishing to me, that Keysight used sense cables only 15 mm long or so, for an instrument that has a maximum output current of 1.4 A and such heavy brass connectorsOutput ratings of the E3649A @ 0°C to 40°CRange 1: 0 to 35 V / 1.4 ARange 2: 60 V / 0.8 A

author: TopLoser
author_rank: Unknown
timestamp: July 25, 2015, 07:44:50 pm
content: Quote from: HighVoltage on July 25, 2015, 06:47:51 pmOther models in the same range go up to 8A, then it might become significant.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 26, 2015, 10:58:35 am
content: Quote from: TopLoser on July 25, 2015, 07:44:50 pmGood point!I have nothing better to do on a rainy Sunday, so I just measured the resistance of this stud with the nice IET LOM 510A MICRO OHMMETER.It seems to be around490 uOhmThen the calculated voltage drop is686 uV at 1.4Aor3.9 mV at 8AThis seems pretty high for such a massive brass studMay be I should send some real current through the stud to see the voltage drop.

author: BravoV
author_rank: Super Contributor
timestamp: July 26, 2015, 11:14:42 am
content: Hmm ... interesting test kelvin probes you got there, let me guess, some precision cutting + "Acrifix" magic ?

author: HighVoltage
author_rank: Super Contributor
timestamp: July 26, 2015, 11:25:54 am
content: Quote from: BravoV on July 26, 2015, 11:14:42 amThe credit for those kelvin clips go torobrenzLook here at time 1:25.I bought this Cambridge micro ohm meter from robrenz with these nice kelvin clips.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 26, 2015, 11:30:36 am
content: Ok, I had to send some current through this binding post and measure the voltage drop.At 1.4A the drop is 510 uVAt 8.0 A the drop is 2.86 mVIt seems like Keysight really wanted to have the last little bit of accuracy increased.Pretty impressive from my point of view.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 26, 2015, 11:39:33 am
content: This morning I took the clamp of the plastic cover and checked the mechanical connection of the cracked part.It welded perfectly and is like new.So, now I have to wait for parts from Keysight.

author: BravoV
author_rank: Super Contributor
timestamp: July 26, 2015, 11:59:57 am
content: Quote from: HighVoltage on July 26, 2015, 11:25:54 amAhh ... no wonder it looks so familiar, its just I forgot where did I see it.For sure when its made by our respected member Robrenz, you must be in a good hand.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 06, 2015, 02:42:13 am
content: Quote from: HighVoltage on July 25, 2015, 10:47:42 amDo you have the Keysight part number for the encoder?Are there any markings on the encoder that indicate who the manufacturer is?Thank you for your help.Regards,Jay_Diddy_B

author: HighVoltage
author_rank: Super Contributor
timestamp: August 06, 2015, 08:21:05 am
content: Quote from: Jay_Diddy_B on August 06, 2015, 02:42:13 amI have not received the confirmation from Keysight but I believe it is the following part number:0960-2545Rotary Encoder-insulated ShaftOnce I receive the invoice and shipping confirmation, I will know for sure and will post it here.Interestingly, the parts are being shipped from different parts of the world.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 15, 2015, 02:32:28 pm
content: OK, a couple weeks later ....Parts arrived ... well only partiallyFront Display cover isnotavailable for sale, but a really nice guy at Keysight Germany found one and made it available, although it is not the Keysight branded one, I think I still like the Agilent name better anyways.Interestingly the "Knob" isno longerfor sale at all from Keysight. But about 2 years ago, I had ordered one extra knob from Agilent and it fitted perfectly for this PSU.Bumpers, front and rear came brand new from KeysightPart Number:E3631-40017Binding post came brand new from KeysightPart Number:E3640-60019The encoder came brand new from KeysightPart Number:0960-2545Here are some pictures of the parts.Now I will install them.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 15, 2015, 02:36:21 pm
content: All parts are now installed and the PSU works perfectly again.Now I will test the unit in a quick test.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 15, 2015, 02:42:11 pm
content: So far I only did a quick test on both outputs and all seems to work perfectly.I will do a more detailed test including rise time and overshoot testing in the next few days.

author: TopLoser
author_rank: Unknown
timestamp: August 15, 2015, 02:55:23 pm
content: Nice job! I'm so glad you managed to find those unobtainium parts.Now... it's time to find some more abused Agilent/Keysight equipment for you!