HPAK 3458A Capacitor Replacement - Page 1
Forum section: electronics / repair

author: Olivia
author_rank: Regular Contributor
timestamp: April 06, 2023, 09:21:44 am
content: Hi there,I have a 1999-2000 Unit that is approaching the end of its current calibration interval and I took note of the "wet" Capacitors inside:Electrolytic Capacitors:A1:A2:A3:A4:C7,C8: 2200µF 35V 0180-4033 16,5mm dia. 32mm long (1189-2253-ND)(DK)C9 15kµF 16V 0180-4034 36mm dia. 26mm long (493-8615-ND)(DK)C10-15: 1µF 35-50V HermeticC17: 22µF 50V 0180-3913 8mm dia. 16mm long (1189-50YXM22MEFRT15X11CT-ND)(DK)A5:A6:C1,C11 680µF 50V 0180-4032 16mm dia. 21mm long (493-1914-ND)(DK)C200-01 47µF 63V 0180-3828 8mm dia. 12mm long (P19619CT-ND)(DK)C8 8300µF 35V 0180-3898 25mm dia. 67mm long axial (493-8635-ND)(DK)C202 330µF 25V 0180-3830 10mm dia. 12mm long (1189-1891-ND)(DK)C203 220µF 16V 0180-3829 8mm dia. 12mm long (493-14723-1-ND)(DK) or (1189-4157-1-ND)(DK)A7:A9:Tantalum CapacitorsA1:C3: 3,3µF 15V 0180-0210 HermeticC17: 1µF 35V 0180-0291 HermeticC20/21: 2,2µF 20V 0180-0197 HermeticA2:C211: 15µF 20V 0180-1746 Hermetic (399-11291-ND)(DK)C701-706 " HermeticC709-710 " 6,5mm dia. 12,5mm long (1189-50YXM22MEFRT15X11CT-ND)(DK)all caps except C702 and C704 are hermetic, those are 22µF 50VAl-Electrolytic NichiconA3:C146/47 15µF 20V 0180-1746 HermeticC181 33µF 10V 0180-0229 HermeticC303 "C353 "C250/51 4,7µF 10V 0180-0309 HermeticC252/53 4,7µF 35V 0180-0100 HermeticA4:A5:C150-55 1µF 35V 0180-0291 HermeticA6:C2 6,8µF 35V 0180-0116 HermeticC4 2,2µF 20V 0180-0197 HermeticC105 "C304 "C12 4,7µF 35V 0180-0100 HermeticC406/07 1µF 35V 0180-0291 HermeticA7:A9:I will add the digikey or mouser part numbers for replacement caps soon.One more thing, does anyone know the lead spacing on A4C9, I forgot to measure that...Cheers,OleEdit: This is list is not yet finished, so if you think that a capacitor doesnt fit please let me know

author: Olivia
author_rank: Regular Contributor
timestamp: April 06, 2023, 10:45:08 am
content: Here is a link to the full version of the Capacitor Cart,it includes both the hermetic tantalum version of the capacitors on A2 and an electrolyte replacementalthough the replacement version is not axially leaded...https://www.digikey.de/short/89rnpjz2

author: Kleinstein
author_rank: Super Contributor
timestamp: April 06, 2023, 10:51:11 am
content: The hermetic wet tantalum capacitors should not need a replaement, unless they are really bad. They are very reliable, but quite expensive parts. So many a cost reason why they are hardly used, maybe for military of aviation.

author: Olivia
author_rank: Regular Contributor
timestamp: April 06, 2023, 11:04:58 am
content: In my case A2C702 and A2C704 are populated with 22µF 50V Al-Electrolytics and based on the CLIP(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/doc/3458A%20CLIP.pdf)Those should be 15µF 20V hermetic Tantalums as well.So I would be replacing the Al-Electrolytics with hermetic Tantalums.

author: Olivia
author_rank: Regular Contributor
timestamp: April 06, 2023, 11:27:34 am
content: My idea for replacing the big outguard cap (A6C8) are:-Using a Radial Cap and bodging the wiring-Using two caps in parallel (399-11637-ND)(DK)-Using a cap with a lower time rating than (1572-1675-ND)(DK)

author: Kleinstein
author_rank: Super Contributor
timestamp: April 06, 2023, 11:38:32 am
content: I see not real need for the wet tantalums. C702 and C704 are just at the supply, before a regulator. So any low ESR type should be OK.I would not expect that the meter to be used at temperatures well below freezing - one of the few reasons to want tantalum capacitors.

author: Olivia
author_rank: Regular Contributor
timestamp: April 06, 2023, 11:46:28 am
content: I´ve removed the tantalums and put in a few more options for the A6C8 replacement:https://www.digikey.de/short/5pww8vcn

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: April 20, 2024, 02:29:54 pm
content: This post would be more useful if your board revisions were presented. For example, A4 REV B has an extra aluminum capacitor designated C17. My unit has an A4 REV A installed, and I would like to confirm C07, C08, and C09 without opening the covers. I would also like to know the lead spacings, independent of looking up each candidate's part number.I don't think you need to replace the tantalum capacitors. The aluminum capacitors are the most important because they tend to age. Depending on the load, they can age faster and compromise the board when leaking out.