Quick Fix: my 2c. fix for HP button key (in this case: HP8662A) - Page 1
Forum section: electronics / repair

author: douardda
author_rank: Regular Contributor
timestamp: April 22, 2018, 09:26:41 pm
content: Hi,I am trying to repair a venerable HP 8662A Signal Generator. No need to make the presentations of the generator I guess.During my repair, I noticed that two key springs were missing. Unfortunately, these key buttons are very hard to find now. Or at indecent price.Fortunately, I found one of the missing springs in the enclosure, but only one. So I had to find a solution for the missing one. And while I was waiting for a quotation from a local spring manufacturer, I had the idea to try to use some packaging plastic and cut a poor-man's spring in that. I tries several widths, and found one that seems to work just fine. The feeling is a bit softer than the other keys, but overall, it works very nicely. Not sure it will last a long time, but hey.Just in case, might help.If someone is interested in the repair of the generator itself (for which I had several issues with the PSU and the LF section), I am writing a series of blog posts onhttps://whatever.sdfa3.org/hp8662a-synthetized-signal-generator-part-1.htmlDavid

author: lowimpedance
author_rank: Super Contributor
timestamp: April 23, 2018, 01:24:05 am
content: Neat fix. And if it doesn't last long, (although I'll bet it will,) cut another !.

author: xrunner
author_rank: Super Contributor
timestamp: April 23, 2018, 02:02:44 am
content: That's a very interesting idea. I've had issues with those before, and went in and flipped over every one of the steel springs to get them to react better after so many years. It's ideas like this that make this forum a very special resource.

author: KE5FX
author_rank: Super Contributor
timestamp: April 23, 2018, 02:24:57 am
content: Quote from: douardda on April 22, 2018, 09:26:41 pmThat's nothing short of Herculean.8662As areheavy.From your photos, it looks like someone has already replaced at least one of the capacitors on the power supply transformer PCB (A7?), but don't forget to check the ESR of all of them, especially the capacitive voltage divider.

author: VK5RC
author_rank: Unknown
timestamp: April 23, 2018, 05:45:40 am
content: I got some clock spring off flea bay for some of my HP iron "clacky HP switches", I found the 2 thou of inch or 0.05mm clock spring steel works well. Trimming it is the hard part.see alsohttp://www.rbarrios.com/projects/hpswitch/re this problem as well7 stories with an HP 8662A, you must be fit!For some other classic repair ideas there is a sticky topic - includes some ideas from KE5FX, Xrunner and othershttps://www.eevblog.com/forum/repair/vintageclassic-renovation-techniques/msg592523/#msg592523I have added yours to it after a 'heads up' by xrunner- Thanks

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: April 23, 2018, 05:54:25 am
content: Good one!

author: eb4eqa
author_rank: Regular Contributor
timestamp: April 23, 2018, 07:06:32 am
content: Yep, I was going to recommend also my own mini-articlehttp://www.rbarrios.com/projects/hpswitch/, thanks Robert.It is an easy fix, you will get it back in working order quickly.Regards,Roberto EB4EQA

author: douardda
author_rank: Regular Contributor
timestamp: April 23, 2018, 04:56:50 pm
content: Quote from: KE5FX on April 23, 2018, 02:24:57 amYep that was a pain in the neck. Once upstairs, took me 15mn to recover :-)Quote from: KE5FX on April 23, 2018, 02:24:57 amYes, the unit has been repaired several times I think. There are several evidences of repairs, and there is also an Agilent sticker somewhere on a board.David

author: douardda
author_rank: Regular Contributor
timestamp: April 23, 2018, 04:59:36 pm
content: Quote from: VK5RC on April 23, 2018, 05:45:40 amQuote from: eb4eqa on April 23, 2018, 07:06:32 amYes I've seen this website and video, thanks.Quote from: VK5RC on April 23, 2018, 05:45:40 amThanks, I missed this topic (so much going on the eevblog forum, it's hard to track).David