is it worth to buy an old non working oscilloscope? - Page 1
Forum section: electronics / beginners

author: RawCode
author_rank: Regular Contributor
timestamp: October 08, 2017, 08:38:55 am
content: Hi there!I'm an italian electronic engineer student. i'm beginning my last year before the bachelor degree(i'm going to study until full degree), and this year we are going to labs! Horray! but i have a question. Do I need an oscilloscope? will i use it in the future? They are pretty expensive for my pocket as a student. Some years ago I bought a kit oscilloscope, with a poor bandwith of 20kHz, but I don't have the "need" of use it, maybe because I'm studying serious electronics right this year, but i don't know.So, inspired by the eevblog's video to hunt cheap analog oscilloscope on ebay, i find one only cheap analog oscilloscope, an Hameg 203-7 with a problem (damn). The seller says that it shows the trace, but the inputs doesn't works. I don't know the severity of the problem, but is an auction and if i win it, it would cost around 30/40 euros. What do you suggest? Is it a easy solving problem?peace

author: Electro Detective
author_rank: Super Contributor
timestamp: October 08, 2017, 09:09:38 am
content: If you want to be a successful student by not wasting time trying to fix someone else's oscilloscope problemTHEY could not fixdo not buy a non working oscilloscopeYou will finish your student course/degree in good health and ALIVE too, by not getting zapped by the oscilloscope power supply trying to fix it (IF it is fixable and parts available)Your multimeter will thank you tooand your family and friends won't have to visit you in hospitalor buy flowers for worst case scenario

author: kripton2035
author_rank: Super Contributor
timestamp: October 08, 2017, 09:22:23 am
content: for 50 euros you can get a working one, if you're patient. If it was free, ok for a non working analog scope.don't forget as a student if you ask, lots of university get rid of their old devices regularly.ask kindly your professors about it there are certainly some deal to make.you will also proove you're interested in your studies, something that seems lost nowadays...

author: RawCode
author_rank: Regular Contributor
timestamp: October 08, 2017, 09:25:29 am
content: Thank you guys, i appreciate your suggestions

author: Rbastler
author_rank: Frequent Contributor
timestamp: October 08, 2017, 09:29:41 am
content: Dont buy a broken oscilloscope as a first time scope. Repairing can be potentially fatal, if you dont know what youre doing and youll need a oscilloscope anyway to repair another one some time.I agree asking your professors. Some are really happy and help you, if you ask kindly and show interest.I assume its this auction ?http://www.ebay.it/itm/Oscilloscopio-usato-/202070083923?hash=item2f0c50c953:g:eksAAOSwnyBZ0KQMBut this could be a bargain:http://www.ebay.it/itm/Fluke-Philips-Pm-97-Oscilloscopio-Spettro-Radiotecnico-Multimetro-/302473435115?hash=item466cd257eb:g:D2kAAOSwOKVZ0TV8Edit: I found that on ebay.it its rather difficult to find scopes, or other equipment. So 50€ for something working could be quite difficult. Ebay.de is better in that regard.

author: RawCode
author_rank: Regular Contributor
timestamp: October 08, 2017, 09:40:14 am
content: Quote from: Rbastler on October 08, 2017, 09:29:41 amyes, is that auction.Thank you for the suggestion, i'm going to evaluate this oscilloscopeI'm also going to ask to my professor if he knows where i can find some cheap oscilloscope

author: kripton2035
author_rank: Super Contributor
timestamp: October 08, 2017, 10:10:44 am
content: don't know where you are in italy, but in south of france, there are some working hameg for 30 euros ready to pickup ...https://www.leboncoin.fr/annonces/offres/provence_alpes_cote_d_azur/?th=1&q=oscilloscope

author: RawCode
author_rank: Regular Contributor
timestamp: October 08, 2017, 10:33:15 am
content: Quote from: kripton2035 on October 08, 2017, 10:10:44 amThanks, i've just sent a message to him to ask if he ships to italy.

author: rstofer
author_rank: Super Contributor
timestamp: October 08, 2017, 02:19:23 pm
content: If I were a student, I would be looking at Digilent's Analog Discovery as a very handy toolbox. It has a dual channel scope, dual channel arbitrary waveform generator, network analyzer, logic analyzer, and a bunch of other essential pieces.http://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/The idea that I could carry my lab in my backpack is pretty compelling.There is a significant student discount available but I don't know how much it is.Download the free Waveforms software and play with the demo mode. It's a pretty amazing tool.

author: kripton2035
author_rank: Super Contributor
timestamp: October 08, 2017, 03:03:33 pm
content: yes it's a nice device, but shipping to europe is $51 ...

author: phil
author_rank: Regular Contributor
timestamp: October 08, 2017, 04:24:28 pm
content: There are distributors in europe, too. There is even one in Italy:https://www.mirifica.it/100270/digilent/410-321

author: kripton2035
author_rank: Super Contributor
timestamp: October 08, 2017, 04:28:36 pm
content: still 150€ + shipping, even at academic price. not the price the OP first post .but yes it's a nice device, better than a 30 years old hameg analog scope !

author: rstofer
author_rank: Super Contributor
timestamp: October 08, 2017, 05:56:29 pm
content: Quote from: kripton2035 on October 08, 2017, 03:03:33 pmDoesn't Digilent have an office in Romania?https://store.digilentinc.com/pages.php?pageid=26I don't know if they handle direct sales from that office.

author: rstofer
author_rank: Super Contributor
timestamp: October 08, 2017, 06:06:16 pm
content: And once you have the scope issue resolved, along comes a need for a signal generator, what about a power supply (albeit limited), logic analyzer or the ever handy network analyzer?I don't use the AD2 every day but when it fits my needs, it works like no other tool on my bench. I really like making Bode' plots (as an exercise) - they were a major PITA back in the '70s when I was in college. Now I can just breadboard the circuit and let the AD2 display the plot. Very cool!For a student on a budget, there simply is nothing like it. It does have to be used with care to not exceed its voltage limits but that shouldn't be a problem. The fact that both scope channels are differential (if you don't use the BNC adapter board) is extremely useful. Ordinary scopes just can't do this because the scope probe is grounded on one side. If you need this capability, there are differential probes available but they cost more than the scope! Or, you can tie up two channels with an A-B math function. That's fine if you have enough channels...

author: oldway
author_rank: Super Contributor
timestamp: October 08, 2017, 06:22:38 pm
content: Of course, I agree, do not buy a non working oscilloscope !If you look after a cheap Hameg oscilloscopes, do not forget the HM412.....They are good basic analog oscilloscopes....often, they only need a little contact cleaner to work like a new one....I think the best Hameg analog oscilloscope is the HM605.

author: Karlo_Moharic
author_rank: Regular Contributor
timestamp: October 10, 2017, 09:17:35 am
content: For 30/40 euros go for it , usually it's a simple fix like a blown capacitor or voltage regulator. Even if you don't fix it you will still learn something

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: October 10, 2017, 09:29:35 am
content: Quote from: Karlo_Moharic on October 10, 2017, 09:17:35 amNah, if the inputs aren't working, chances are that someone shot the input stage e.g. by applying a too high voltage in 50Ohm mode.The damage could be major. Trying to repair this as 1st electronic project is most probably a bad idea.

author: tggzzz
author_rank: Super Contributor
timestamp: October 10, 2017, 09:36:28 am
content: While at university, concentrate on doing those things that are best done at university; leave other things until outside university (e.g. during holidays or after graduating). Hence study and get good exam results.As averyrough rule of thumb, technicians fix equipment, whereas engineers use equipment to develop new products. Both are valuable; which do you want to be?Having said that, fixing equipment can help you understand the theory of how it works and also the practical difficulties of making something that implements the theory. That can be valuable.If your current objective is to poke around in circuits, either get a working scope or use the universities' scopes.If you decide to repair a scope, be prepared to find you can't repair it.

author: bd139
author_rank: Super Contributor
timestamp: October 10, 2017, 09:50:40 am
content: A broken oscilloscope is a whole EE education. It’s a combination of reverse engineering, understanding the signal processing chain and practical skills. . Really you can learn a lot about impedance, high frequency design,, frequency compensation, differential amplifiers, Schmitt triggers, power supplies, High voltage safety and even a bit of physics with a dead one. Not to mention an education on construction and production of an actual device including mechanical considerations.Problem is you usually need a working one to fix it. Buy a working one then a dead one.Reverse and forward engineering are both important. The skills you learn above will help you when you jump into an actual job and get a turd on your plate. A lot of people just start again because they can’t reverse engineer and document something.

author: adras
author_rank: Regular Contributor
timestamp: October 10, 2017, 12:33:10 pm
content: I have no idea what I'm talking about, but especially in old devices the parts which fail are leaking/old capacitors. I've seen quite some cases where the fix was just to replace the broken capacitors. In some cases it's obvious which are broken, in others you need to unsolder and test them. That's also something which basically everybody can do.There was one repair video from Dave where he had the original manual, which also included detailed trouble shooting information. That was awesome, you saw at which testing points which values were expected, and which fault it is if the voltage is wrong. I think that's also something everybody with a multimeter and soldering skills can do. But it's hard to get such a manual I think.I guess all the other things which can go wrong require a very sophisticated knowledge where you start to reverse engineer the circuits. Reverse engineering also requires you to read every single datasheet of every IC which is used so it's very, very time intense. And if you have that kind of knowledge you can earn hundreds of dollars in an hour, so it's not worth the time to fix something that cheap. Unless you just want to tinker around.But unless you're using spare money I agree with the others, get a working one. As soon as you've got your degree and a Job you should earn enough money to just give it a try without loosing a lot.

author: tggzzz
author_rank: Super Contributor
timestamp: October 10, 2017, 02:07:19 pm
content: Quote from: adras on October 10, 2017, 12:33:10 pmThanks for responsibly including the caveat! I agree with your conclusions, unsurprisingly.However, these things can often be fixed without understanding every IC's datasheets. Unlike designing a circuit, when faultfinding a circuit you can usually adequately guess each IC's parameters without needing a datasheet - especially op amps.You must, however, have a good schematic down to the component level - where "component level" is defined as the level at which components can be replaced. For old HP/Tektronix scopes, that is transistor/resistor/capacitor/IC, and that is one reason they remain popular. For more modern equipment, it is the board level.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 10, 2017, 02:26:40 pm
content: Quote from: RawCode on October 08, 2017, 08:38:55 amMy 2p worth....Unless your school is under-equipped you don't need one so defer the purchase.In my experience second hand test equipment that doesn't work probably REALLY doesn't work since the person selling it often has the skills to fix simple problems so you will get something that is either hard to fix or unfixable... either way a huge waste of time. There are exceptions, especially related to test equipment that nobody wants [must dig out my recently purchased HP interferometer counter one day] but it's a minefield.IMHO.... Save up for a Rigol 1054Z instead or whatever is current when you actually need one.

author: james_s
author_rank: Super Contributor
timestamp: October 10, 2017, 05:14:57 pm
content: I've had a lot of enjoyment fixing older oscilloscopes and other equipment but if you're looking for a first scope, buy one that already works. Chances are you'll need it to fix a broken scope you might pick up later. It's a bit of a gamble but you can save a lot of money buying broken equipment and fixing it but you don't always win. Sometimes you open the thing up and the damage is beyond repair.

author: bd139
author_rank: Super Contributor
timestamp: October 10, 2017, 05:17:23 pm
content: You win regularly. I just won. 200MHz Tek 475 with DM44 module for £30. One duff tant that took me 30 minutes to trace out and replace.

author: Old Printer
author_rank: Frequent Contributor
timestamp: October 10, 2017, 08:38:08 pm
content: I would also recommend looking into the Analog Discovery 2. I have had mine about a month and am very impressed with it. It is a learning tool, and as such there are limits to it's capabilities - like bandwidth. It has a wide variety of electronics tools for both analog and digital signals. If it's specs are within what you need it is surely worth a look. If you don't know the specs of what you need, it might be premature to buy a scope at this point. As for the analog vs digital scope argument, both have certain signals they are best looking at. I have two older Tektronix analog scopes that both work well, but the digital scope in the AD2 allows me to study very slow signals better than an analog, not to mention taking snapshots of certain signals. Look on YouTube. Tomtektest in particular has some very in-depth studies using the AD2, and Derek Molloy also gives it a pretty clear demo. For learning it is a great tool. Dave

author: james_s
author_rank: Super Contributor
timestamp: October 17, 2017, 07:46:21 pm
content: Quote from: bd139 on October 10, 2017, 05:17:23 pmSure, but you could have also found that the CRT was shot, some unobtanium custom hybrid or any number of other things. I too have won much more often than not, but I've also bought equipment that turned out to be scrap.

author: innkeeper
author_rank: Unknown
timestamp: October 17, 2017, 08:55:02 pm
content: is it worth getting a broken peace of test equipment, fixing it and using it sure, it is a lot of fun, and gives you great satisfaction.would i pay money for it, if i were in collage, heck no! if you can pick up a free peace of broken gear go for it. my guess is if you post around that your a collage student looking for broken test gear to repair and use that people will give you stuff .. heck you can probably even get some working stuff that way.

author: cdev
author_rank: Super Contributor
timestamp: October 17, 2017, 11:11:40 pm
content: Why is shipping for an Analog Discovery so much to Italy?That's what I would expect shipping for a boat-anchor to cost, not a solid state device.

author: RawCode
author_rank: Regular Contributor
timestamp: October 18, 2017, 08:07:06 am
content: Thank you for all these answers. I really appreciateI lefted that auction as you suggestedI found some other interesting working oscilloscope.A fluke pm3370b (seems to have some digital capabilities)60MHz at 175 euros plus shipping and a hp 1742a 100MHz 175 euros without shipping. What do you suggest? They're a bit expensive, aren't they?I also asked to my professor, and he said that it's a good idea to have an analog oscilloscope rather than a digital one. First of all for the cost, second one because it's more difficult to use it and more instructive.Inviato dal mio Nexus 5 utilizzando Tapatalk

author: oldway
author_rank: Super Contributor
timestamp: October 18, 2017, 08:26:37 am
content: PM3370B, I strongly discourage because the printed boards are pluggable and inaccessible ..... it is very difficult for repair unless you have spare printed boards ...If you want a digital oscilloscope, buy a new and current device, not an old technology.For the HP1742A, yes, if it works properly only.

author: borjam
author_rank: Unknown
timestamp: October 18, 2017, 09:12:00 am
content: Quote from: RawCode on October 18, 2017, 08:07:06 amI am not in any "auctoritas" position, but I strongly disagree with that. A one week exposure to old, analog oscilloscopes can be good, but modern oscilloscopes are digital. And DSOs are indeed superior to analog in many aspects. DSOs are different beasts of course.On a limited budget even cheap ones like the Siglent SDS1202X-E (two channels) or the Rigol DS1054Z (four channels) can as a bare minimum help you become really familiar with digital scopes and will surely be useful despite their limitations.Also, although not a panacea, the deep memory in these scopes can really help to sort out digital stuff, which makes them better than oldDSOs with very limited memory.

author: bd139
author_rank: Super Contributor
timestamp: October 18, 2017, 10:04:33 am
content: Those second hand analogue units are both rather expensive!If you’re going to spend €175, get a credit card and stick a DS1054Z on it and pay it off monthly or something. The value doesn’t depreciate a lot so if you want rid of it or something then you’re not going to lose much cash.Maybe €50-90 for a working analogue scope. €0-40 for a dead one depending on the model. I wouldn’t spend any more.While if I had a low budget I’d go with an analogue, the professor is wrong. A digital scope is easy to use, perhaps even easier than an analogue. If you have an analogue scope only there is a ton of stuff you would require external equipment to measure.

author: JoeO
author_rank: Frequent Contributor
timestamp: October 18, 2017, 11:07:36 am
content: As an instructor at a local Community College, I find the professor's advice very strange. We use digital Teks in the lab. I personally bought myself an Owon 7102V. It is 100MHz, 2 channel digital scope with VGA output. I use it to display traces to students using the projector in the classroom. I also bought 2 batteries and a carrying case which allow me to set it up anywhere I want without having to worry about a power cord. The whole shebang was less than $500.I also have a Rigol 1054Z.Digitals have a steeper learning curve especially when you are used to the look and feel of a Tektronix. But for someone new to the field, digital is the way to go, now and into the future.

author: borjam
author_rank: Unknown
timestamp: October 18, 2017, 11:30:07 am
content: Quote from: JoeO on October 18, 2017, 11:07:36 amI agree. And the recent availability of really affordable oscilloscopes (I can vouch for Siglent and Rigol myself) it's a no-brainer. With the insane price hikes of textbooks(*) we are talking about an oscilloscope for the price of three or four books.(*) Curiously The Art of Electronics is not part of that insanity. But the prices of some more fundamental text books has gone insane beyond imagination. Not so many years ago those books sold for maybe 30 - 40 dollars. Now you can't find them for less than $130. To add insult to injury, how many of those insanely priced books are printed in China?

author: bd139
author_rank: Super Contributor
timestamp: October 18, 2017, 12:03:36 pm
content: You can thank PH and Pearson for that. They spent most of the 1990s and 2000s inflating the prices like the estate agents did with property in the UK. Everyone is f**ked now.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 18, 2017, 12:08:20 pm
content: It might be worth getting/upgrading to a more up to date Professor.

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: October 18, 2017, 12:12:08 pm
content: Quote from: bd139 on October 10, 2017, 05:17:23 pmThat was a very fortunate score! Although I am pleased for you, I am also very surprised you found one that cheap! Was this from the UK or the US site? I have never seen one go for as little as that on eBay UK! You don't generally see them with the DM44 module either, unless they are from the US. You do seem to get them that cheap on the US site from time to time, but shipping to the UK/Europe tends to be rather prohibitive. Of course they sometimes start very low and I have bid up to £50 on a couple in thge last 3-4 weeks (I am looking for a repair/parts donor), but they always end up going for at least twice that or more and I always end up outbid. I think more than £40-50 is too much for a non-working one. If its working or only with minor faults then maybe. Still, I keep on looking....BTW, does anyone ever buy the £200-£250 ones?

author: bd139
author_rank: Super Contributor
timestamp: October 18, 2017, 12:37:13 pm
content: UK site. It ended in the middle of rush hour in the morning, was buyer collect, not shown working and was dirty in the picture so it went low. It had a few issues with it, documented in another thread which I have mostly resolved. Only one issue left with the horizontal sweep. To be honest, I'm slightly tired of it as I have a nice digital scope already so it's been chucked back on ebay:http://www.ebay.co.uk/itm/253214365129(ownership time slightly exaggerated to avoid HMRC attention)I keep buying old scopes and they keep eating up my time from other projects!I wouldn't pay £200-250 for one! You can get a far better piece of equipment for not much more than that!

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: October 18, 2017, 01:24:31 pm
content: Quote from: bd139 on October 18, 2017, 12:37:13 pmIt always helps when it is nearby to collect and I guess in the middle of the rush hour is an awkward time to watch the auction so perhaps that would have contributed. Seems to have cleaned up very nicely!Quote from: bd139 on October 18, 2017, 12:37:13 pmAgreed, but there seem to be quite a few scopes at silly (opportunist?) prices. I just wondered if anyone actually buys them. However, at £100 for the one listed is tempting (might have made an offer!) but unfortunately Isleworth is too far for me to collect.

author: bd139
author_rank: Super Contributor
timestamp: October 18, 2017, 01:41:19 pm
content: It did. I'm quite surprised at how Tek stuff usually cleans up. If the controls are intact it usually works!I've certainly had a few bargains in the scope department. I don't think I've paid more than £30 for a scope on ebay ever.I would send it but unfortunately while not particularly fragile if well packaged, couriers can break anything here!

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: October 18, 2017, 02:03:10 pm
content: Quote from: bd139 on October 18, 2017, 01:41:19 pmYes, I absolutely understand the reluctance to send via courier, especially RM!

author: cdev
author_rank: Super Contributor
timestamp: October 18, 2017, 03:29:49 pm
content: Good luck on your studies!

author: james_s
author_rank: Super Contributor
timestamp: October 20, 2017, 06:20:29 pm
content: I've long been a proponent of starting out with an analog scope but these days I'd say do that only if you can find one for very cheap or free. Digital scopes have gotten quite good, and even an older one will do things that no analog scope can do. There are certain niche applications where analog is better but when you come across such an application you'll probably know.