looking to buy a used analog scope. which are reliable? - Page 1
Forum section: electronics / testgear

author: playboy_shrek
author_rank: Contributor
timestamp: September 02, 2021, 05:31:12 am
content: going to start working on audio circuits at home. and one of last couple of things I'm missing is the oscilloscope, as a student in my last year at EE I can't really afford to drop 250+ on a new digital scope. even though that's cheap for scopes standards and I have a couple of USB acquisition tool although they are far too crappy for something like audio and they definitely don't handle higher voltages that well.trying to score a decent analog oscilloscope for around 100 either online or maybe looking in the used stuff stores around to see if I can find something. any recommendations to which specific models or brands hold up well and don't usually require much repairs. like good caps and all that. I don't lack experience buying used measurement tools I bought a Keithley 175 multimeter and it worked okay for a while but the LCD screen on it is half dead after a few months usage.I don't need any digital functions or anything I'm just working on supplies and audio circuits and analog stuff.

author: AVGresponding
author_rank: Super Contributor
timestamp: September 02, 2021, 05:47:39 am
content: Could you clarify what you mean by "higher voltages"?Given their age, most analogue scopes are likely to need some form of maintenance or repair at the price bracket you mention. The US seems to have a decent supply of HP and Tektronix ones at affordable prices, HP 54xxx are quite nice to use, and 4xx series Teks are well understood so you'd have no issues getting help with repairs etc.

author: playboy_shrek
author_rank: Contributor
timestamp: September 02, 2021, 05:53:04 am
content: They have poor impedance. And i dont think they go higher than like 25v unless i get special adapter and probe which iant worth it these things are not accurate at allI saw a sony tek 335 for my price range. If i cant find one locally ill pick up something like that

author: Andrew_Debbie
author_rank: Frequent Contributor
timestamp: September 02, 2021, 06:17:07 am
content: Quote from: playboy_shrek on September 02, 2021, 05:31:12 amYou should be able to get a Hantek DSO2C10 for well under $200. Last I checked, Prices for shipping from 'US Warehouse' are around $185 on Aliexpress.

author: james_s
author_rank: Super Contributor
timestamp: September 02, 2021, 06:22:22 am
content: Almost any analog scope you find will be at least 20 years old so in terms of reliability it's going to be a crapshoot. The A-list stuff like Tektronix, HP, Hitachi, Kikusui, etc tend to be the most well documented so your chance of being able to repair that stuff is better than average, but on the other hand it tends to be complicated. It's the sort of thing where you might have to just see what's available, it used to be very easy to find a used analog scope in good shape but supplies have largely dried up as they have gotten older and fewer of them still work.

author: mansaxel
author_rank: Super Contributor
timestamp: September 02, 2021, 06:36:45 am
content: Get a Tek 465. More than you'll need. (the TE addiction devil on my shoulder says "Then you'll need another one, to keep the first one in spec"; this is to be embraced)Then get a differential probe. That will stop you from killing the scope, the DUT and yourself.Most useful if you find yourself building a hollow-state circuit, as audio-interested people sometimes do.

author: Fungus
author_rank: Super Contributor
timestamp: September 02, 2021, 07:35:23 am
content: Quote from: playboy_shrek on September 02, 2021, 05:31:12 amAt this stage pretty much all $100 analog 'scopes are "works in progress". You'd have to be incredibly lucky to score a good one.And... you often need another oscilloscope to troubleshoot your oscilloscope when it does wrong.Quote from: playboy_shrek on September 02, 2021, 05:31:12 amI don't see how you can afford not to.Reliability aside, they can do so much more than an analog 'scope ever will, eg. FFTs.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 02, 2021, 11:55:20 am
content: If you are into audio, I think analog apparently has advantages and is used by audiophiles more than digital.You can do X-Y on almost all old analog scopes and get Lissajous figures (really cool) which some folks use to get phase measurements. You can align you analog stereo so that both channels are "in phase" if you care about that sort of thing.Dig scopes dont do X Y easily.The digital scopes do not respond as well at low freq. Too much aliasing?For audio you do not need a 100 MHz scope a 10 MHz will work fine or maybe better. You probably only need two channels. Lots of companies made decent scopes.For better analog I think Tek is probably the best choice. There are a lot of them and lots of support forums like the one on Groups.ioDont get one with a small screen.In my experience with maybe 50 different scopes, the low freq old scopes work more of the time than the fancy ones, probably because there is less to go bad. Also a lot easier to fix.Try looking at a hamfest and ask around. Some old fart like me might have one sitting around that would be really cheap. Plug it in. Try Craigslist. I would avoid ebay for this sort of thing. The people selling mostly do not know anything about the instrument and the ship cost is considerable.Most old analog scopes do not have on screen stuff like freq readouts though. You said you did not care. The better ones do, however it is something that can frequently go wrong in these old scopes.I have an Agilent digital scope and use that almost all of the time. I also kept a Tek 475 (good scope) and an HP 1980, a scope that cost about $20,000 in 1985, when you could buy maybe two Corvettes for that price.(don't buy one of these)Always use a ten times scope probe. Direct probes have some use but mostly stay away from them, they will burn out your front end fast. And then you will be looking for a hard to find FET.You mentioned high voltage, tube audio usually uses maybe 350-450 volts, a ten times probe will bring that down to 35-45 volts. Most of the time you will be measuring less.Some old analog scopes will sense the 10X probes and align the screen to reflect the measurement. Cheaper ones will not and you will have to divide by 10. If you took Diffy Q this should not be too hard HA!.Remember that you need a probe that is capacitance matched to you scope to make it work correctly. Otherwise the trace will not be good at all.

author: bd139
author_rank: Super Contributor
timestamp: September 02, 2021, 12:04:20 pm
content: There’s no such thing as a reliable analogue scope. Buy two. One to fix the other one. This is however good fun.Tektronix 465 (preferably 465B) is probably the easiest to look after. Followed by Hameg units. If you’re doing audio you don’t need a lot of scope.Buy a 100x probe if you want high voltages. There’s no other option!

author: 25 CPS
author_rank: Frequent Contributor
timestamp: September 02, 2021, 02:32:39 pm
content: As others have said, analog scopes are all getting older now. It's probably less about which ones in general are the most reliable these days and more a game of attrition. Once you strike out the dead or partially working scopes and you're looking at what's left that's fully functional, which do you like best?My best recommendation is to go over the local classifieds and local surplus stores and see if you can get something you like that's been tested and demonstrated as fully working. One of the surplus shops near me was selling military surplus Tektronix 2235s for about $200 that were lightly used, maintained, and kept calibrated until the government unloaded them, and the shop was doing a full test and demonstration on each one being sold to a customer. At least this way, you start out of the gate with something that works instead of having a project on your hands right from the start.

author: bd139
author_rank: Super Contributor
timestamp: September 02, 2021, 02:42:07 pm
content: I wouldnt touch a 2235. Notoriously unreliable power supplies that like to go kaboom.Here’s one I blew up earlierhttps://www.eevblog.com/forum/testgear/tektronix-2235-repair-thread/

author: Fungus
author_rank: Super Contributor
timestamp: September 02, 2021, 02:44:18 pm
content: Quote from: Wallace Gasiewicz on September 02, 2021, 11:55:20 amSure they do. I don't know of a DSO without an XY mode.PS: Real audiophiles adjust their cable lengths to get the channels in phase. It's the only way to be sure.Quote from: Wallace Gasiewicz on September 02, 2021, 11:55:20 amYep. If possible get afixed10x probe to avoid accidents. You can get cheap ones for about $5 that will be fine up to 100MHz or so.

author: Cerebus
author_rank: Super Contributor
timestamp: September 02, 2021, 02:55:41 pm
content: Quote from: Fungus on September 02, 2021, 02:44:18 pmHe saideasily. While almost any digital scope willhavean X Y mode, my experience with trying to use it is that it is invariably crappy. Also digital scopes don't have a Z input like many analog scopes do, which limits you to the less interesting uses of X Y mode.

author: 25 CPS
author_rank: Frequent Contributor
timestamp: September 02, 2021, 03:01:53 pm
content: Quote from: bd139 on September 02, 2021, 02:42:07 pmInteresting. The stack they had for sale at this place was all military surplus AN/USM.... designation takes on the 2235 so I don't know how far they differed internally but they did have enhanced shielding and the screen over the CRT so they were hardened in some ways. I don't know if that extended to ruggedizing the power supplies or anything else.I still definitely recommend starting out with something that already works instead of buying something that already needs work to get going, never mind long term reliable.

author: Fungus
author_rank: Super Contributor
timestamp: September 02, 2021, 03:11:49 pm
content: Quote from: Cerebus on September 02, 2021, 02:55:41 pmSelect "XY" mode in the menu.Quote from: Cerebus on September 02, 2021, 02:55:41 pmI've seen people say that but it usually comes down to adjusting the memory depth and timebase. You're not driving the XY amplifiers directly and all that other stuff counts.(Maybe that's what you mean by "easily", that point is that it will do it just fine)Besides, most DSOs will show phase angle on screen as a numerical measurement, no need to guesstimate the angle by looking at green lines.

author: mlloyd1
author_rank: Contributor
timestamp: September 02, 2021, 03:19:44 pm
content: For what you need, I can recommend a used Hitachi V665.You can see a picture here:https://www.ebay.com/itm/303966066593?hash=item46c5ca17a1:g:UIoAAOSwkhJgfK11It has nice features (including handy cursor readouts) and from my sample of 1, has been extremely reliable.You can always upgrade to something nicer later if you need to, but this will serve all your needs well.I bought one new MANY years ago (during mid 1980s), still have and use it occasionally, even though I have since acquired much fancier (and more expensive) equipment.Good luck!mlloyd1

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 02, 2021, 04:40:20 pm
content: Quote from: Fungus on September 02, 2021, 03:11:49 pmYea, there is less need for XY if you have the functions of a DSO, but Lissajous patterns are pretty!I tried to do Transistor curve tracing on my DSO. I eventually got it to make a terrible pattern that was only discernible after examining it for a long time. It took me a long time to get the scope to even show me this. Probably because I don't know how to use all functions of a DSO in the first place. You have to set too many thingsBesides, XY is not really X vs Y but a digital representation in a DSO. A real X vs Y does not use time base for example.

author: jonpaul
author_rank: Super Contributor
timestamp: September 02, 2021, 04:41:39 pm
content: Tektronix 22xx especial 2465BAvoid Chinese junk\Jon

author: Cerebus
author_rank: Super Contributor
timestamp: September 02, 2021, 04:47:13 pm
content: Also, avoid French junk.

author: 2N3055
author_rank: Super Contributor
timestamp: September 02, 2021, 05:12:22 pm
content: Quote from: Cerebus on September 02, 2021, 02:55:41 pmMy MSOX3000T has Z mode. It is not real Z mode (fully analog) but more of a blanking circuit (with adjustable level). Still much better than none. There are (where) some Tektronix TDS3000B/C series where you had full X-Y-Z (also Z for blanking) and you could show video picture...I guess nobody cares anymore ..Using X-Y to measure phase is something that will work even with crappiest digital scope. You cannot do good scope art, but Lissajous figures are just fine.Many people just don't know how to set it up.For instance, you need to enable hi res mode to lower the noise. Signal is very low in frequency anyways. And you need to play a bit with time base. But you can get very usable results for just looking at Lissajous patterns.Scope art, for that you need analog scope.You can also use the phase measurements on scopes that have it. Or if you just want signals in phase, you just overlap traces on top of each other and move things around until they overlap. If we exclude electronics (filters and delay inducing elements) only source of audible phase difference is physical placement of speakers, microphones and listener's ears.In which case you might not want to measure phase delay, but a physical time delay (time of arrival) in normal timebase.You can also do many things you cannot to with analog scopes. Capture single pulse and then freeze it.For audio work, a cheap digital scope and USB sound card and software will give you fantastic capabilities. Or Analog Discovery, that is a electronics laboratory in a small box.Of course, that is all more than 200 USD.OTOH for 200 USD you won't get much, however you look at it. Analog CRT or DSO.For just looking at the signal shape even those handheld gizmos are good enough for audio range.Old analog scopes are either nostalgia and familiarity (after 30 years, they feel like old friends), sometimes better specs for niche things (like scope art), or sheer coolness of old CRT "ping machines".But make no mistakes, you will not have only one in the end (one working and multiple parts donors), it will cost you much more money than a new modern decent 500-1000 USD DSO in a long run and they will be a project for themselves most of the time.People have them and keep them same as an oldtimer cars. If you are doing it on purpose, are prepared to work on them and spend money on repairs, they are good fun.If you really set your heart on analog scope, I wish you good luck hunting for one that works well and won't give you problems.

author: Johnny10
author_rank: Frequent Contributor
timestamp: September 02, 2021, 05:24:09 pm
content: Where are you located?

author: nctnico
author_rank: Super Contributor
timestamp: September 02, 2021, 05:24:31 pm
content: Quote from: 2N3055 on September 02, 2021, 05:12:22 pmYup. For which purpose would you need XY mode when working on audio circuits?QuoteChecking phase alignment is the only thing I ever used XY mode for on a DSO and it worked just fine.Personally I'd rather use one of the cheap handheld DSOs or the cheap tablet scope from Fnirsi than an old analog scope. Being able to make single shots, look at signals below 50Hz, do measurements and make screendumps make life so much easier. One of the first pieces of equipment I paid a lot of money for was a DSO. Never went back to an analog scope.

author: playboy_shrek
author_rank: Contributor
timestamp: September 02, 2021, 05:44:27 pm
content: Massachusetts.also wondering if the T912 is decent.

author: Johnny10
author_rank: Frequent Contributor
timestamp: September 02, 2021, 05:57:41 pm
content: I would think something would be available on craigslist in your price range.I see a couple in Boston area for 125 or Best offer.Why is everyone so worried about getting the perfect scope first time around? (Although I must admit I couldn't decide for months on my first scope either).I ended up with 10 or so after my first Rigol scope.I used an analog Tektronix 2465 for Audio when I first started and I still like to pull it out on occasion. A bit pricier than what you want.On my local Craigslist there are two cheap scopes, A B&K for 50 and an old tube Tektronix 516 for 125 Make Offer.And you can always get your money back if you buy or sell local.Shipping is the killer for cheap scopes.Doesn't the YouTuber D-Labs use a 50 dollar B&K Oscilloscope and a 25 dollar signal generator in his guitar amp videos?

author: PaulAm
author_rank: Frequent Contributor
timestamp: September 02, 2021, 05:59:06 pm
content: If you're just doing audio work, look for a Tek 5000 series. They're lower bandwidth cousins of the 7000 series and people practically give them away.If you're near Boston, check out the MIT flea, it's tentatively scheduled for Oct 17. You could probably find something there for cheap.

author: playboy_shrek
author_rank: Contributor
timestamp: September 02, 2021, 06:04:31 pm
content: alright, I have to go through Boston and near that area multiple times a week, I will just try to find something and see what happens.do any of these models come with a built in function generator?

author: armandine2
author_rank: Frequent Contributor
timestamp: September 02, 2021, 06:09:08 pm
content: which is reliable versus who is reliable:

author: Johnny10
author_rank: Frequent Contributor
timestamp: September 02, 2021, 06:10:31 pm
content: Here is a D-Labs video might help.

author: james_s
author_rank: Super Contributor
timestamp: September 02, 2021, 06:58:50 pm
content: Quote from: Fungus on September 02, 2021, 02:44:18 pmThey have the feature, but it's completely worthless on my DSOs. I use the XY mode occasionally when I'm working on vector game boards and my 465B displays a near perfect picture. My DSOs display a bunch of noise with something occasionally vaguely recognizable. That is one of the few things that an analog scope still does much better than any DSO I've tried, but it's definitely a niche use case.

author: james_s
author_rank: Super Contributor
timestamp: September 02, 2021, 07:00:18 pm
content: Quote from: playboy_shrek on September 02, 2021, 06:04:31 pmI've never seen an analog scope that contained a built in function generator and wouldn't want one if it did exist. Separate units are far superior and a lot more versatile. I don't want to have to drag my scope around every time I need a function generator.

author: mansaxel
author_rank: Super Contributor
timestamp: September 02, 2021, 07:08:37 pm
content: Quote from: PaulAm on September 02, 2021, 05:59:06 pmI've got a 5400 in my repair queue; current analysis is, as to be expected, a shorted tantal cap on -30V. (And the -30V is reference for all other low voltages, so it needs to be present.) I've bought replacement low-ESR electrolytic caps, Würth brand; I just need to clean the bench enough to have room for the scope...If successful this repair will only have required a DMM with a good low Ω range.Oh, and I paid ~65 € for it, and then I splurged on an original paper manual, because the scans available on the Net are crap for that particular one.

author: mansaxel
author_rank: Super Contributor
timestamp: September 02, 2021, 07:17:34 pm
content: Quote from: james_s on September 02, 2021, 07:00:18 pmI have to concur. While keeping my eyes open for the right one (a -hp- or perhaps R&S one), I've made do with a FeelTech 3200S Chinesium FG for a couple years now. (OK, OK, There's a SG505 with balanced output option in my shop too, but that's sine only and honestly, I could have done all I do with it, perhaps not as elegantly, with the FeelTech. ) The 3200S is advertised on Aliexpress for around $ 70.And, if you're really in a pinch and just need a square wave to check treble response, use the probe calibrator