Agilent 34401a repair with oval "Shift" button . Manual Needed - Page 1
Forum section: electronics / repair

author: tru3533
author_rank: Regular Contributor
timestamp: May 18, 2017, 02:36:21 pm
content: Hi,Looking for newer edition of the service manual for the Agilent 34401a with oval "Shift" button.Anyone who can help?

author: Cerebus
author_rank: Super Contributor
timestamp: May 18, 2017, 02:50:07 pm
content: Quote from: tru3533 on May 18, 2017, 02:36:21 pmIt's on the Keysight website, Manual Part Number 34401-90013.

author: tru3533
author_rank: Regular Contributor
timestamp: May 18, 2017, 07:03:45 pm
content: Thank you so much for your reply.I got hold of 2 pcs 34401A on Ebay.Managed to repair 1 so far, It looks like they have been messed with alot, so the front is possibly switched.From what I now can see it looks like an older version on the motherboard.The regulator is different on the motherboard I have left to repair, so the schematic don't match.So still looking for the manual.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 18, 2017, 07:28:08 pm
content: What is the built date of your latest model with the new regulator?

author: Cerebus
author_rank: Super Contributor
timestamp: May 18, 2017, 08:29:22 pm
content: I don't think Keysight have allowed a manualwith parts list and schematicsinto the wild that corresponds to the board revision you have there. The older ones have an LM2925 which I think was discontinued which would explain why there's a different chip where that was on the older board.

author: tru3533
author_rank: Regular Contributor
timestamp: May 18, 2017, 08:52:08 pm
content: HighVoltage: I don't have any idea where to find that.Cerebus: Yea, I don't think that Keysight have this on their web page also, but you never know what can be laying around

author: HighVoltage
author_rank: Super Contributor
timestamp: May 18, 2017, 09:25:56 pm
content: You can look at some ICs for a date code, it allows you to narrow down the built yearWhat is the marking of the regulator?Can you find a datasheet for the regulator?I will open up my latest model 34401A and see if it has already this new regulator.After many repairs of older 34401A meters, I have not seen this regulator before.

author: tru3533
author_rank: Regular Contributor
timestamp: May 18, 2017, 11:59:28 pm
content: I think I was little bit to hasty about the age. Looking only at the REV 001. Assuming older versionCloser look reveal Agilent branding only with no HP logo. So conclusion: this board is "New"5V regulator is from ON Semiconductor CS8126 D2PAK-7http://www.onsemi.com/PowerSolutions/product.do?id=CS8126Barcode sticker on Motherboard have 201209 in the second last number group. My best guess is year 2012 week 09The repaired motherboard have number 200113Connector for flat cable to front display is not "PRESS TO REMOVE". Text on silkscreen is still there, but now the connector is a normal "lift up the the hinge and remove cable type"Black colored ground terminals.U701 Agilent branded

author: tru3533
author_rank: Regular Contributor
timestamp: December 13, 2017, 01:50:10 pm
content: Looking in my "want to repair shelves" the Agilent 34401A was sticking out like a sore thumb, reminding me about some unfinished business.I sure would love to get this instrument back in business, so I try again.Is there anyone who can help me out with this manual?

author: HighVoltage
author_rank: Super Contributor
timestamp: December 13, 2017, 02:43:33 pm
content: Quote from: tru3533 on December 13, 2017, 01:50:10 pmHere is a link to an older manual with schematics and parts listhttp://file.yizimg.com/327204/2009111205044857.pdfBut, be careful, it only applies partially to the latest model with oval shift buttons

author: tru3533
author_rank: Regular Contributor
timestamp: December 13, 2017, 04:31:46 pm
content: Thank you so much HigvoltageUnfortunately I have this manual already.The reason for the need of the newer manual is a high voltage blown out area where the old and new don't match.

author: Dr. Frank
author_rank: Super Contributor
timestamp: December 13, 2017, 04:55:16 pm
content: These old (initial) schematics are the only one available for the public, and I'm very sure about this.Agilent and later KS did / do not publish schematics anymore, so updates aren't available either.That was already the case, when the 34410/411A came out.Maybe you should contact KS support directly, if they can provide these schematics to you, personally..For the 34410/411, these documents were available for some time on a hidden agilent folder, on request from a customer, obviously.Frank

author: tru3533
author_rank: Regular Contributor
timestamp: December 13, 2017, 05:08:03 pm
content: Thank you Frank for the information, I'll give it a try