HP 1980B Oscilloscope troubleshooting and repair - Page 1
Forum section: electronics / repair

author: Cubdriver
author_rank: Unknown
timestamp: December 03, 2015, 02:52:36 am
content: I just received this beastie after purchasing it last week on the 'Bay, where it was listed as 'Doesn't power up... ...missing fuse...'. It arrived well packaged (actually double boxed), and while a bit rough isn't in terrible physical condition. I 'borrowed' a fuse holder cap from another piece of equipment, popped in a new fuse and after plugging in BOTH ends of the power cord (for my initial try only the instrument end was connected - d'oh!!) it came at least partially to life, with the fan running, several indicators lighting up and a somewhat dim, not entirely focused display that's biased up from the center on the CRT and jittery in the vertical direction. The only key that seems to affect it is the beam finder, which gets the four traces more or less to mid screen with reduced horizontal width. It seems to completely ignore my poking and prodding at any of the other keys.It displays a '25' on the numerical LED above the control knob; turning the knob causes no apparent change to anything. I'm presently scrolling through the PDF scan on the Keysight website in an attempt to get some troubleshooting hints and try to determine if the 25 has any significance as a failure indicator, and have also ordered a copy of the paper manual from everyone's favorite auction site.I expect it'll likely need filter caps at the very least, but I'm pretty encouraged by the fact that it displays text and traces. If anyone who's worked on one of these wants to chime in with suggestions, all would be welcome.-PatPowered up, overall view:Controls:Display:Display with beam finder activated:

author: Cubdriver
author_rank: Unknown
timestamp: December 03, 2015, 03:53:16 am
content: More photos, showing the open chassis. There are at least two electrolytics on the bottom that need to go...Underside, overall:Detail showing unhealthy electrolytics:Topside, overall:

author: Cubdriver
author_rank: Unknown
timestamp: December 03, 2015, 07:13:48 am
content: A bit of disassembly revealed the source of a rattle that I thought I heard when unboxing the scope, but it stopped immediately, so I had hoped it was my imagination. No such luck. When I went to remove the second pair of vertical channels (a plug-in), it didn't want to come out, and the ejector handle seemed to be grinding. A bit of digging revealed a small piece of white ceramic with a couple of pins on it wedged in among the mechanism. Oh crap!! Further examination after removing the side panel revealed the source of the chunk of ceramic - a crushed chip on the sweep control panel. The panel was a bit of a bear to get out, and my guess is that at some point someone used a screwdriver to help 'coax' the panel out and broke the chip by prying on it. My initial fear was that it was an EPROM of some sort, and would be unobtanium, but as it turns out it's simply a lamp driver IC (custom made by HP, of course) and replacements were found on the 'Bay and a pair have been ordered already. And on that note, time to call it a night and hit the sack.-PatSweep panel:Overall view of the rear, showing broken wall from 2x17 header and piece of IC package:Detail of damaged IC package:

author: mcfudge
author_rank: Contributor
timestamp: May 12, 2016, 02:53:14 am
content: Your post and pics are much appreciated. I received a 1980B last week and plugged it in a few days ago. It worked for about 15 minutes then I heard the dreaded snap, crackle, and pop noises and smelled burned out components. I still had an image on the crt and the front panel lights were on but I unplugged it promptly. I suspect one or more caps popped. I tried to remove the large top and bottom covers tonight without success. The side covers came off by sliding them from front to back with some effort and after removing the handles. I wonder if my top and bottom covers are sticky and will need some considerable prying. Please advise. Thanks in advance.

author: AF6LJ
author_rank: Unknown
timestamp: May 12, 2016, 03:32:57 am
content: Oh Dear You are lucky that chip is still available Wow.

author: skennedy
author_rank: Contributor
timestamp: May 12, 2016, 04:12:06 am
content: I too recently purchased a non working 1980B. Missing the second vertical channel strip entirely but otherwise looks complete. A pretty amazing scope considering how old it is. Upon power up I noticed the snap and pop, fearing the worst I investigated the source. It turned out the typical mains filter caps had totally spilled their guts. Removing them entirely and powering up the scope again gives a working front panel, horribly loud fan and an error code to do with calibration. The CRT fuse has blown so that would look to be the first place to start my investigation.mcfudge, you should check the mains filter caps on your scope. To access just remove a few screws on the back panel around the mains input.

author: wn1fju
author_rank: Frequent Contributor
timestamp: May 12, 2016, 12:34:00 pm
content: In addition to straightening out the caps in the power supply, be aware that these beasts use elastomeric connectors. The four big rectangular white hybrid chips make contact to the boards via them as do many boards behind the front panel. Over time, these connectors flatten out or tarnish, making the connections unreliable. I was able to keep my 1980B running for a fairly long time by rotating or re-positioning the connectors, but eventually was forced to remove and mechanically clean them with very fine wet sandpaper (ouch!). Probably not the best solution, but the scope has been fairly stable. Also check the non-power supply electrolytics as I had one in the timing circuitry leak and go bad.

author: Cubdriver
author_rank: Unknown
timestamp: May 12, 2016, 03:41:45 pm
content: McFudge -I haven't had a chance to do much more with the scope since starting this thread, but in the off chance that you haven't yet gotten them removed can tell you that the top and bottom covers are secured by a single screw each; the screw is located in the center of the back edge of the panel. It should be a captive screw, with some sort of retainer on the inside of the panel to prevent its loss. Once the screw holding the cover on has been loosened enough to come free of the threaded hole it's in (and, being captive it should draw the panel back with it as it is loosened), you should be able to pull the panel rearward another eighth inch or so and then lift it up and free.I just grabbed one of them (I got a couple of more since for a song on the 'bay) and took a few quick iPhone pics of cover removal:The retaining screw:The cover position when the screw is tightened (note that the side cover is loose and slightly rearward of where it should be; it too should be even with the flat edge of the aluminum frame corner):The cover position when the screw has been loosened to the point of disengagement with the frame:The cover lifted away(note that once it moves back, it LIFTS up and away - it does not slide off straight rearward - you can see the edge that extends down slightly and fits in the groove along the side - if you try to slide it straight off this will catch and prevent the cover from continuing rearward):I hope this helps.-Pat

author: mcfudge
author_rank: Contributor
timestamp: May 12, 2016, 04:51:18 pm
content: Cubdriver that was fantastic. I now have the covers off. Wow I cannot believe I overlooked the obvious frayed white hp stickers.Thanks also to wn1fju and skennedy (good call!) for additional suggestions! This will be a nice addition to my DSO if it works out.

author: Cubdriver
author_rank: Unknown
timestamp: May 12, 2016, 06:01:27 pm
content: Glad to help, and yeah, I'd say that cap's best days are behind it...Good luck with your repairs. I need to get my butt in gear and start futzing with mine, too. They're definitely cool old scopes.-Pat

author: woodchips
author_rank: Frequent Contributor
timestamp: August 29, 2016, 09:16:19 am
content: I have a couple of these, and also a full set of manuals from Manuals Plus, and still can't work out what it is for.It is a 100MHz analogue scope, but what is the point of all the digital stuff? Is it only to draw envelope diagrams on the screen for someone to check that the displayed waveform is inside the envelope? I have had a good search in the manuals and can find no details of whether it can digitise the actual waveform? What is the point of having deflection factors of 276mV/div or 101us/div? Strangely I have a flyer describing printing or plotting the screen, static as well as dynamic traces, so how were they captured? This printout also has strange calibration per division settings.The good news is that by searching I foundemperoroftestequipment.weebly.comwhich has a review of many pieces of test equipment, spent a good couple of hours reading it so far and not finished.One 1980 was dead, one sort of works. Even with the manuals how do you get the sort of X and Y plug ins out? Had to near dismantle the whole scope and then the cables needed a steel fingered hand 2" wide for access. They are sort of plug ins because they have no release catch and then pull out as in every other scope. They are just front panels, but screwed to the main analogue board in the bottom of the scope. To get at the eleastomeric connections all this has to be dismantled. Seems a waste of time to me!

author: Cubdriver
author_rank: Unknown
timestamp: August 31, 2016, 02:43:11 am
content: The 1980s have been on the back burner for a while now, unfortunately, due to other projects and simply a general lack of time and motivation. I hope to get back to them again as winter rolls around. I e the meantime, I have plumbing and heating to get finished before the snow flies.Thanks for the interesting link - that was a good read (still more to go, too), though his tastes seem to run to more 'modern' gear than mine generally do. He needs to get a 3439A, 3440A, 3450A and 3460B for his voltmeter collection, and he's missing a bunch of counters as well.-Pat

author: woodchips
author_rank: Frequent Contributor
timestamp: August 31, 2016, 05:50:12 pm
content: Yes, finished after three nights of reading.I wonder how much time he spent on fixing it all, lots of hours it seems.Seems to have missed that the 3581 wave analyser looks amazingly like the 3580 spectrum analyser. In fact if you use the 3581 self scan mode it is a not bad audio spectrum analyser. And cheap! No one knows what a wave analyser is now.

author: fred-bloggs
author_rank: Newbie
timestamp: December 17, 2018, 04:15:25 pm
content: Dear Sir - Although some time as passed i was wondering if the HP1980B Oscilloscopes maybe available For Sale ? Regards Marc

author: Oldtechman
author_rank: Newbie
timestamp: September 17, 2024, 11:12:28 pm
content: Hi there I am new to this site. I just received my hp 1980b oscillscope of course it came from ebay. So far I have been lucky everything seems to work accept the trace intensity is to high. I have the big book for this scope and tells me how to adjust the limit for the trace signal. Now the kicker it doesn't say where the controls are. Any help would be appreciated.I have been in electronics since 1978. Use to work on Tvs. I worked for the Navy for 30 years. I am now retired. I still tinker with electronics repairing old computers and now I moved to test equipment. My hobby keeps me out of my wife's hair. I would like to say hi to everyone. Cubdriver you inspired me to join this forum thank you.

author: wn1fju
author_rank: Frequent Contributor
timestamp: September 17, 2024, 11:48:38 pm
content: Am I missing something? Seems clear from the photo in the service manual. Now, you will have to look around for that metal cover. Hopefully it isn't buried beneath a board, but it is probably towards the rear of the scope where the connections to the CRT are.You have tried fiddling first with the front panel intensity control (intensity button on upper left and main control knob)?

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 18, 2024, 01:55:30 am
content: I have a 1980 Scope that I have repaired. Works OK.As wn1fju said, first try the intensity adjust on the front panel. This adjust should vary the intensity quite a bit and around maybe 40 is a good place to see a good trace.You can adjust the intensities of different traces like the delayed trace also.You also know that this is a big CRT with lots of volts from your TV days......It is a nice unit and the "autoscope" function works nicely on mine....Some old proprietary chips but these seem to not go bad....I think this thing was the first "digital scope" are at least close to the first one...

author: Oldtechman
author_rank: Newbie
timestamp: September 20, 2024, 12:58:52 pm
content: I found my intensity limit adjustment. It was under the HP-IB card.thank you for the help.

author: Oldtechman
author_rank: Newbie
timestamp: September 26, 2024, 11:55:22 am
content: I would like to thank everyone for their suggestions for fixing my 1980B oscillscope. This may be hard to believe. I fixed my signal trace intensity problem with a hammer. The top cover had a couple of deep dents in it. When installed the the intensity problem showed up. When the top cover was removed the signal trace and text display was find. I started looking for pinched wires could not find any. I looked at the cover and found the dents. After beating them out with a car body hammer. I reinstalled it and everything looks good. Now the only problem I have is channel 3 signal trace not correct. I will be pulling that module out and look for bad caps. When I did the auto scope I hear popping sound. I beleive the sound is the relays switching. Thanks for the advice.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 26, 2024, 01:28:23 pm
content: A very fortunate outcome. Perhaps make sure the HV connections at the CRT are clean and in good shape.

author: Raindog
author_rank: Contributor
timestamp: December 02, 2024, 01:30:06 am
content: I have two of these scopes, one has the digital storage option and the other does not. I originally saw one of these in the movie "Brainstorm", I couldn't identify this instrument until years later. The non-digital version I have works fine except I had to track down a pesky fault that generates the sweep voltage for the on-screen readouts. The other unit does power on however, but the rotary encoder does not work, and the digital storage option does not function and causes the unit to lock up. Even though I have newer scopes I like this thing, it's a HP 853A size scope that fits nicely in a rack, I am currently looking for the unobtanium HP 1965A universal counter option.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: December 03, 2024, 12:37:54 am
content: I got my "Universal Counter" from e bay. It works but it does not have a good oscillator, so the freq readout suffers, Also the freq is very hard to adjust. The other readings I get like rise time are not that great either so probably this would take another week of adjustments, starting with figuring out what adjusts would be appropriate......also the battery is a problem and needs to be replaced with another type for cost reasons, Space for battery is limited. I eventually used big coin cells.But it is kind of nice for 60 bucks US.