HP 184-A no display on the CRT - Page 1
Forum section: electronics / repair

author: Lolucoca
author_rank: Contributor
timestamp: October 29, 2017, 08:12:56 am
content: Hi! I'm thinking about buying a dead HP 184-A oscilloscope with the 1809a vertical amplifier for 15 bucks. It's a really good scope (4ch, 100MHz, 10mV/Div) but the guy says it doesn't give him a display and that it happened apruptly. He also says he can't find any manuals for it (which isn't a problem, he googled the serial number of the thing, there are manuals for that scope out there). Could it be a battery backed RAM that's gone bad (well, of course, those batteries are well beyond their prime)? I think this is a problem with a lot of older digitizing oscilloscopes out there. I hope it's not. The good thing about the HP 184 is that it's like a modular system where you can just slot out the vertical amplifier and use it in another HP184. Could it be a power supply issue or like a CRT issue? Do you guys have any experience with those things? Please let me know!

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 29, 2017, 01:10:16 pm
content: Are you sure that's a digitizing scope? I looked it up and it does't look like one, it looks very analog to me, are you sure you posted the correct model number?Regardless, something is not getting power, whether it's the board or the tube remains to be seen.

author: Lolucoca
author_rank: Contributor
timestamp: October 29, 2017, 02:31:42 pm
content: Well, the guy says it has a memory function but I'm not really sure on that. It's hard to make out any detail on the picture he sent but what I was able to see is that it's using an 1809A as the vertical amplifier and an 1825A as the time base generator. I'm not really sure whether the scope really has any kind of memory built in but I guess that's a good thing cause that means it's all analog (thank goodness, no ASICs to replace!). Analog stuff isn't quite as hard to replace as digital integrated circuits from 40 years ago. The scope itself seems to be in fairly good condition, it's a bit dirty but nothing out of the ordinary for such an old scope.

author: pelule
author_rank: Frequent Contributor
timestamp: October 29, 2017, 05:07:57 pm
content: Well I have such a scope (includinge the 4ch and a spectrum analyzer plug-in). I can proof, it is a classic analog scope with NO storage function./PeLuLe

author: Lolucoca
author_rank: Contributor
timestamp: October 29, 2017, 05:19:33 pm
content: That's great news, honestly. Nothing worse than having to deal with some stupid ASIC that no one seems to have ANY data for.

author: edavid
author_rank: Super Contributor
timestamp: October 29, 2017, 05:28:47 pm
content: Quote from: pelule on October 29, 2017, 05:07:57 pmThat is not right either. The HP 184A is a variable persistence analog storage scope. It sounds like you are thinking of the 182T.OP, it definitely could be a power supply or CRT issue.

author: Lolucoca
author_rank: Contributor
timestamp: October 29, 2017, 05:35:39 pm
content: Whatever, for 15 bucks it's worth a shot. I'll look into like picking up the scope maybe tomorrow or the day after tomorrow. It's a 160km drive but for a 100MHz scope (if I can actually get it working) it's a good deal. Even with gas prices being as screwed as they are right now.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: October 29, 2017, 06:10:11 pm
content: I have an HP180A, with 1801A dual channel 50 MHz vertical and 1821A timebase/delay generator. The mainframe (containing power supplies and CRT circuitry) is very similar to the 184A. Mine went "display gone" one day, and I traced the problem to a bad Zener diode in the mainframe. It was easy to find (the old Zener actually broke in half) and easy to fix, and the old scope works perfectly.I'd love to have one of the two Spectrum Analyzer plug-ins for this old thing.