About hp 8903b key metal spring strips - Page 1
Forum section: electronics / repair

author: kirby64
author_rank: Newbie
timestamp: June 24, 2022, 03:01:44 am
content: Hi i have a hp 8903b audio analyzer and yesterday one of the keys stopped working the keys on this type of equipment usually suffer from stiffness on the keys due to some issues with these thin metal strips that work as return springs. I removed the front keyboard and of course one of the metal strip actually broke in half does anyone know where i can get another or what kind of thin metal sheet i could buy where i could cut something to the same size as the original to repair it?Let me know thank you

author: strawberry
author_rank: Super Contributor
timestamp: June 24, 2022, 07:04:02 am
content: 0.1mm stainlesshttps://www.joom.com/lv/products/5c1b1b191436d401012bac4benough for 1000 springsspring steel could be too hard to cut by hand (laser)

author: kirby64
author_rank: Newbie
timestamp: June 24, 2022, 02:42:22 pm
content: That link didn't work for me for some reasonDSFHKUYB 0.01Mm Thickness Silver 304 Stainless Steel Fine Plate Sheet Foil 100Mmx1m for Electronic Equipment - 1Pcs,0.01mm x 100mm x 1000mmhttps://a.co/d/27RqTl2I found this should be the same im thinking?

author: strawberry
author_rank: Super Contributor
timestamp: June 24, 2022, 06:17:20 pm
content: I think they use steel tension to flip a key.0.01mm could bee too thin(or possible)

author: Stray Electron
author_rank: Super Contributor
timestamp: June 24, 2022, 06:58:31 pm
content: My experience is that those strips get broken because the contact on the backside of it gets dirty and doesn't make contact so people pound on the key until the metal strip gets broken. But if you clean the back side of the strip so that it makes contact then it will still usually work but won't have the snap feel of the original HP key.I cut narrow strips out of IBM punch cards so that they are narrow enough to fit under the "bubble" of the metal keyboard strip. Dip the card in alcohol put it under the strip and press down lightly and then pull the card through so that the card and alcohol clean the back side of the buckle strip and the other contact under it.Those buckle strips are usually long strips that go all of the way across the keyboard so it usually has many key contacts on it so they would be very difficult to replace. Also the strips are spot welded to the circuit board at both ends and also between each contact and the strip has "bumps" in it over each contact so that the contact is "normally open".

author: kirby64
author_rank: Newbie
timestamp: June 24, 2022, 07:18:21 pm
content: I think these are different kind of strips they are mainly used as a return spring to pop the key back up not to contact bridge or actuate the switch.What thickness and strip material would be recommended so i can try making new strips for them?

author: kirby64
author_rank: Newbie
timestamp: June 24, 2022, 08:38:26 pm
content: Ok after researching on several forums including this one it appears this type of switch is called a "Bill West Switch" it was used on various Hp gear the spring strip measures 0.588 in. long by 0.140 in. wide by 0.002 in. thick the US patent says the original metal of the spring is "high-carbon steel".I will order some carbon steel shim stock of 0.002 inches and some0.002 inch stainless steel feeler gauge stock and will report back and see what worked the best thank you everyone for the help!

author: Gregegg2
author_rank: Newbie
timestamp: May 01, 2024, 05:56:26 am
content: Hello Kirby64, curious to find out if the shim stock worked? i.e carbon steel or SS? If not, all good.