HP8753(C) Frontpanel Test Procedure - Page 1
Forum section: electronics / rf-microwave

author: kruszi
author_rank: Newbie
timestamp: August 16, 2016, 09:07:59 am
content: Hi,by luck I got one HP8753C Network Analyzer. Unfortunately the front panel seems to lag a little bit (keys need to be pressed hard). So I am thinking of a repair. (Any recommendations?).To kind of sort out problems I'd like to perform a test on the front panel. According to the Service Manual there are two front panel tests (one sequential/guided, the other one "free"). So I managed to start these "external" tests. According to the manual the screen should show informations on the procedure - but there are no informations. After starting the test ("Execute Test") the softkey description changes to "SK1, SK2, ..." and nothing more happens. Testresult says "IP" (in progress).Any ideas how to perform this test properly?Thanks

author: hendorog
author_rank: Super Contributor
timestamp: August 16, 2016, 09:15:53 am
content: No idea about the test, but I replaced the rubber keypad on mine with one from ebay. It has one button that isn't the correct name (SEQ should be RECALL)When it was in pieces I cleaned the PCB side of the button pads with IPA. I didn't touch the pads on the rubber keypad as I read somewhere you can clean off the conductive coating.The buttons work much better now than they did with the old keypad.Seller is here:http://www.ebay.com/itm/Agilent-08752-40003-KEYPAD-FOR-8752C-NEW-/282093914296?hash=item41ae1b88b8:g:~wwAAOSwgY9XfyU6

author: cncjerry
author_rank: Unknown
timestamp: August 17, 2016, 05:19:59 pm
content: What do I need to know about the 8753C keypad? Been looking at them lately and have seen some with the bezel pulled off, etc so there must be common problems with those switches, no?

author: hendorog
author_rank: Super Contributor
timestamp: August 17, 2016, 08:03:57 pm
content: Quote from: cncjerry on August 17, 2016, 05:19:59 pmThe menu key cover is often missing on these. The bezel itself is usually still there.The menu key cover has very fragile attachment tabs. It is likely removing it will damage the tabs and then it cant be put back on. This part needs to be removed to remove the screen polariser which blocks some light so removing it makes the screen brighter, or even just to clean it.

author: kruszi
author_rank: Newbie
timestamp: June 30, 2017, 01:10:40 pm
content: Just in case somebody else has problems with his/her HP8753Cand thinks about a keypad replacement:Not all have these rubber keys - mine for example has "real switches". (See attached image)These are horrible for repair: Their (red) bodys are made of plastic which is inserted into PCB through holes and melted down on the bottom side. This way the plastic body is fixed to the PCB. But there is literally no chance for removement / repair. You can not reach the contacts on the PCB since you can not remove the red body of the switch without destroying it. I am thinking of redesigning these bodys using a 3D printer and ABS ...

author: fcb
author_rank: Super Contributor
timestamp: June 30, 2017, 03:35:59 pm
content: Also got a HP8753C - I really don't like the look of those buttons!

author: hendorog
author_rank: Super Contributor
timestamp: June 30, 2017, 11:57:45 pm
content: Possible to blow it out and then wash it in IPA?Not sure if that would do any harm to the conductive surface though.

author: BigBoss
author_rank: Regular Contributor
timestamp: July 01, 2017, 04:07:04 pm
content: The keyboard should be washed in a liquid ( pure water ) within a ultrasonic cleaner.We solved a kind of problem with this method so many years ago.But I don't know is there still ultrasonic cleaner ..The best way is to replace, I'm sure there are some cleaner spares..