Capacitor condition in CRT board for HP1630A - Page 1
Forum section: electronics / beginners

author: ArturP
author_rank: Newbie
timestamp: September 15, 2023, 02:40:33 pm
content: I recently got HP1630A logic analyser and all runs good as far as I can tell. But when I open it just to inspect the condition I realised that two Nichicon capacitors on the CRT bard are looking "strange"(blue ones on my pictures). At first I thought that these are leaking electrolyte, but it looks more like a glue than any other leaky capacitor I could find on internet. I am attaching few pictures of them and I would appreciate if someone saw something like this and is it really capacitor leak?At the moment I am not powering up the analyser, and I didn't yet remove the board. But probably I will replace them anyway.Thanks

author: BrokenYugo
author_rank: Super Contributor
timestamp: September 15, 2023, 02:57:19 pm
content: Looks bulged, that's usually evidence enough to replace at this age.

author: ArturP
author_rank: Newbie
timestamp: September 15, 2023, 04:39:12 pm
content: Thanks. I was just wondering because the metal does not look bulging it is just like a drop of glue on top. But you are right they are old and I am replacing them in any case. And I like your username 😁 (I guess you refer to a certain car)

author: u666sa
author_rank: Frequent Contributor
timestamp: September 15, 2023, 04:41:17 pm
content: If you got a logic analyzer you went pretty far down the rabbit hole. At this point you should have an LCR meter, along with multimeter and oscilloscope.I recommend you get Hantek 1833C..You see the problem with caps is the following. Looks yea, looks are important, and your cap looks bad. But there are a ton of situations where cap looks good, and you check it out with capacitance meter, and it checks okey. But in actuality cap is bad. You often, very often, get TVs and power supplies, and caps check out okey on capacitance meter, but they are not okey, they are bad, and often times bad enough so your electronics do not turn on. So a proper LCR meter is a real money maker. Get one.If you got one buldged cap on your board, and you do, that means other caps should also be checked.Moreover, new caps sometimes are bad. So replacing with new caps can sometimes lead to electronics not turning on.

author: CaptDon
author_rank: Super Contributor
timestamp: September 15, 2023, 05:29:08 pm
content: It almost looks like they sealed the vents with conformal coating. I guess that would cause one heck of a bang when those capacitors self destructed.I saw an old Sylvania D19 chassis launch a metal can capacitor right through the top of the plastic back!!! That chassis was one that had a voltage doubler arrangement with the line power going through one of the doubler capacitors. The can split in a circular fashion near the bottom and launched like a rocket! The owner of the set said he nearly shit when it happened and he was afraid to get near the set for fear something else would explode inside!!

author: ArturP
author_rank: Newbie
timestamp: September 15, 2023, 05:50:41 pm
content: Thanks. I do have what I consider good LCR meter, BK Precision 880. So I will definitely try to check them.

author: ArturP
author_rank: Newbie
timestamp: September 15, 2023, 05:56:32 pm
content: Yes, it does look strange, like a sealed and not like a leak. That is why I posted it.