Light bulb needed for HP 5065a - Page 1
Forum section: electronics / general

author: sanleontexas
author_rank: Contributor
timestamp: June 12, 2025, 09:00:46 pm
content: After a lightning strike my power flashed off for a second or two. I scurried over to the rack with mytime equipment to turn things off in case there would be a likely second strike and found, as expected,the battery light on and the Continuous Operation light off. When I tried to return it to lock operation,no joy. After a few minutes of thought and fear, I swapped the lamp with the other one. Much relief.Then spent much time looking for a replacement, starting with HP. The parts listing shows it's an HPmanufactured item, which likely means it's supplied by a vendor but HP wanted the business. Naturally,at this point the parts for HP relics are no longer available. Would anyone have a suggestion as to whereone of these beauties might be found? The HP p/n is 2140-0025, and the listing shows that it's a #327bulb. The ones I've found on ebay aren't quite the same, but the bases look like they may be correct.

author: factory
author_rank: Super Contributor
timestamp: June 12, 2025, 09:16:47 pm
content: You can confirm the type of lamp by sliding it out the back of that lens/holder and looking for a lamp number.David

author: edpalmer42
author_rank: Super Contributor
timestamp: June 12, 2025, 11:31:21 pm
content: The threaded part is a sleeve that the bulb is pushed into from the back. Use a knife blade or similar to help pry it out of the sleeve.

author: sanleontexas
author_rank: Contributor
timestamp: June 12, 2025, 11:51:00 pm
content: You're right. I thought of that at first and tried to separate the two with a knife blade,but no luck. I was able to push against the glass and it slid right out. It's an S387.Thanks a bunch, you two and EEVBlog came through again!

author: edpalmer42
author_rank: Super Contributor
timestamp: June 13, 2025, 03:13:57 am
content: Push against the glass?Did the green plastic part seperate from the metal sleeve? That's not supposed to happen. The idea is that you grab the plastic part and then screw or unscrew the bulb from the socket. If the parts seperate, you'll have trouble installing and removing the bulb.

author: KE5FX
author_rank: Super Contributor
timestamp: June 13, 2025, 05:13:21 am
content: I'm embarrassed to admit I didn't get how these lamps worked at first, either. Cracked the plastic on one of them trying to get at the bulb.It doesn't screw into the plastic lens, you just pull it out by the base and push the new one back in, then screw the whole assembly back into the panel receptacle.CM-387NDis the part number at Digi-Key. Get 'em while you can, they are now marked as NRND. Although there seem to be someother manufacturersthat are not showing it as obsolete.

author: marcumr
author_rank: Contributor
timestamp: June 13, 2025, 06:04:19 am
content: Hi, I saw that you are talking about light bulbs.I am trying to restore an HP 8640B (a fabulous machine but very complicated for me), and I am looking for a light bulb for the power switch. Can you tell me where I can find one?Thank you very much.Mauro

author: edpalmer42
author_rank: Super Contributor
timestamp: June 13, 2025, 07:34:15 am
content: 327 bulbs seem to be widely available on the auction site. It looks like they're used in some Cessna planes. There are even a few LED replacements. I've also found that the 327 bulb (28V@40ma, 4K hrs life, 4 lumens) can be replaced by a 376 bulb (28V@60ma,25K hrs life, 4 lumens). In the 5065A, the bulbs are run at ~18V so a 376 bulb should last forever.

author: sanleontexas
author_rank: Contributor
timestamp: June 13, 2025, 12:17:48 pm
content: There wasn't enough of the bulb extending from the sleeve, and I couldn't pry between themwith a knife blade. The only way was to remove the lens and push the glass end. It came outeasily that way, and the lens won't slide back into the 5065A easily, but it will go back in. Thebulbs are plentiful on ebay. The 327 came from the HP parts listing, but that isn't the numberon the bulb.

author: edpalmer42
author_rank: Super Contributor
timestamp: June 13, 2025, 06:34:48 pm
content: There was enough room to pry with a knife blade, you just haven't seen it done so you weren't sure what to do. No problem.However, before you reinstall the bulb, you should use a small amount of cyanoacrylate glue to reattach the plastic lens to the metal sleeve. Otherwise, you won't be able to screw the sleeve in or out. I just looked at mine and I had one that needed repair.

author: KE5FX
author_rank: Super Contributor
timestamp: June 13, 2025, 10:28:45 pm
content: Quote from: marcumr on June 13, 2025, 06:04:19 amThose are physically similar bulbs, in that they press into the button's plastic lens assembly the same way as the ones being discussed here, but they are A1H neon bulbs rather than 28V incandescents. Do a search onA1H neonand it should bring up some sources.

author: sanleontexas
author_rank: Contributor
timestamp: June 14, 2025, 02:56:57 pm
content: I really didn't want to use super glue on it, someday I may have a need toseparate them again. I aligned the knurling, swapped bulbs with the inte-grator limit lamp, ordered 10 GE bulbs for 12 bucks(shipping included), andall is good. When the bulbs arrive I will stick a new one in the integrator limitlamp. Everything is jake. It wouldn't even have been powered on, but I'mrunning long period comparisons between it and two Z3801As. Except fora few power interruptions and time for replacing the GPS receivers withSynergy boards, it's been ongoing now for about 4 months.

author: KE5FX
author_rank: Super Contributor
timestamp: June 14, 2025, 03:21:56 pm
content: Quote from: sanleontexas on June 14, 2025, 02:56:57 pmThat suggests that you still may not get how these work. The lens and the sleeve it's bonded to have absolutely nothing to do with the ability to remove and replace the bulb. There is never a reason to separate the lens and the sleeve.In fact, if you don't bond them together well, the lens will probably come off in your hand the next time you try to unscrew it from the panel, and the bulb will then be much harder to remove.

author: chuckb
author_rank: Frequent Contributor
timestamp: June 14, 2025, 08:36:55 pm
content: These pix may help.