What Should I Be Looking For When Buying a "New" Analog Oscilloscope?  - Page 1
Forum section: electronics / testgear

author: MistaMun
author_rank: Contributor
timestamp: July 29, 2015, 12:52:00 pm
content: Hello!I have been eyeballing for an oscilloscope on Craigslist and eBay for some time now but I finally found an oscilloscope right on $50!It's a Tektronix 455 but I have no clue on anything about this oscilloscope. Is there something that I need to be aware of? Are there some kinds of quick tests that I could do on site? I am highly doubting that the seller even has a probe to start off with so if it comes to that point, is there a way I can test it without the probe? (Maybe with some alligator clips)P.S. The owner said "I got a clean legible trace with some 60Hz noise when I touched the input" and I have no clue what he means by that.

author: JackP
author_rank: Regular Contributor
timestamp: July 29, 2015, 12:58:28 pm
content: The '60Hz noise' is the mains frequency that his body is picking up - like an antenna. That is normal. You could always buy some probes beforehand and take them with you since you'll need them anyway. Only £10 for a crappy pair, but that's all you need for starters.

author: MistaMun
author_rank: Contributor
timestamp: July 29, 2015, 01:00:33 pm
content: Thanks for the reply! Unfortunately, I am going to have to go pick it up today cause this guy does it first come basis and I don't think its going to be still there until tomorrow. Ugh. Is there any way that I can "test" without the probes?

author: JackP
author_rank: Regular Contributor
timestamp: July 29, 2015, 01:13:03 pm
content: To be honest, unless there is some form of self-test functionality there isn't much to test without probes (hard to access the inside BNC connection without causing any shorts to the outer shell). The fact that it picks up the mains is a good sign, but you won't be able to test things like triggering without a probe for the cal output. Maybe someone else can give you some tips on what to watch out for with these scopes. Sorry I can't help you more!

author: MistaMun
author_rank: Contributor
timestamp: July 29, 2015, 01:18:17 pm
content: You gave more insight that I had couple hours back. Thanks for all the help!

author: w2aew
author_rank: Super Contributor
timestamp: July 29, 2015, 03:29:03 pm
content: Quote from: MistaMun on July 29, 2015, 01:18:17 pmIf you can bring any kind of probe to connect to the compensation output - do that. If not, then at least a wire you can use as an antenna for 60Hz pickup, etc.Very basic things to check:- run the vertical attenuator (scale) through each range, hopefully with a signal attached. You should be able to see if it works over at least part of the range with the comp signal.- run the sweep control through each of it's steps to be sure you get a trace/sweep at each s/div setting - no dead settings.- if you're familiar with the trigger controls - check that AUTO gives you a trace regardless of settings, and that when set to NORMal, that LINE and INT trigger modes work as expected.- With no input (or shorted input, or input coupling set to GND), the trace should be flat (no 60/120 ripple).- trace should be focus-able with focus control- trace should be bright enough to see without setting intensity to max (although you might be at/near max at the fastest sweep speed - this is ok)- make sure vertical and horizontal position controls are near center (not too far towards one extreme or the other) when trace is centered.

author: edavid
author_rank: Super Contributor
timestamp: July 29, 2015, 04:06:17 pm
content: All you need to do is bring a 1 foot piece of wire... connect it between the calibrator output and the inputs.

author: commie
author_rank: Frequent Contributor
timestamp: July 29, 2015, 04:09:17 pm
content: Don't waste your money, save some more and get a digital like the DS1054Z.

author: w2aew
author_rank: Super Contributor
timestamp: July 29, 2015, 06:51:54 pm
content: Quote from: commie on July 29, 2015, 04:09:17 pmSure, will a entry level digital scope give him more functionality and automatic measurements - yes. But, scopes like the one you mention cost 7x or more what he'll spend on the old analog scope.To me, getting a scope *sooner* (with available funds) rather than later (after saving for 7x longer) will advance his learning, his visibility into circuit behavior, his intuitive understanding of what a scope can give him, etc., while he saves up for a DSO. Then, when he's ready with the funds, he'll have a much better understanding of what a scope brings to his bench, he'll make a more educated decision on what DSO to buy, as well as being able to recoup most of the original price on the analog scope should he choose to sell it.So, I say - go for the inexpensive used analog scope now - learn, play, fix, investigate, troubleshoot, debug, etc....! Upgrade later...

author: Lightages
author_rank: Unknown
timestamp: July 29, 2015, 07:09:58 pm
content: A good used analog scope at $50 is not useless not a waste of money. A good multimeter and a scope like that will get many things done and could save him money in the long run.

author: MistaMun
author_rank: Contributor
timestamp: July 29, 2015, 07:26:29 pm
content: Quote from: w2aew on July 29, 2015, 06:51:54 pmThat is exactly what I had in mind, learn. I got the oscilloscope! And here are some pictures of them!

author: mazurov
author_rank: Frequent Contributor
timestamp: July 29, 2015, 07:27:18 pm
content: Quote from: commie on July 29, 2015, 04:09:17 pmThe input range of 4xx series is much better. If this scope is functional it will survive much longer in the care of a curious beginner.

author: mazurov
author_rank: Frequent Contributor
timestamp: July 29, 2015, 07:40:10 pm
content: Quote from: MistaMun on July 29, 2015, 07:26:29 pmWhile shopping for probes you can check the input without any tools. Switch to 50 mV and put your finger inside the input connector (see picture). You'll get DC offset plus some line noise.

author: PaulAm
author_rank: Frequent Contributor
timestamp: July 29, 2015, 07:40:45 pm
content: Believe it or not, a lot of digital infrastructure was designed, built and troubleshot with analog scopes, primarily because the silicon needed to realize DSOs weren't even a glimmer in an engineer's eye. DSO's have tremendous advantages, and current price/performance is amazing, but that doesn't make analog scopes useless.Fairly often if I'm just looking for a signal and I'm not interested in measurements, I'll use an old analog scope I have kicking around. Primarily because I can turn it on and see what I want to see without having to wait for it to bootgoing through splash screens or navigating menus. Sometimes you need a BFH, sometimes a tack hammer will do.If you can afford a DSO, great! If all you can afford is a $50 analog scope, you can still learn a lot and then move on when your requirements demand it and finances allow it. If the choice were between spending $400 on an analog scope or a new Rigol,that's a different question entirely.

author: w2aew
author_rank: Super Contributor
timestamp: July 29, 2015, 07:52:39 pm
content: Quote from: MistaMun on July 29, 2015, 07:26:29 pmAwesome! Looks like it's in great shape too! Controls are basically identical to the 465B that I have in my lab, and is featured in many of my videos (like the Triggering controls video, and many more). Congratulations and enjoy!

author: MistaMun
author_rank: Contributor
timestamp: July 29, 2015, 08:02:06 pm
content: Quote from: w2aew on July 29, 2015, 07:52:39 pmThis oscilloscope is awesome! I don't know about the great shape though, it has some large cracks on the bottom but I guess that's more of cosmetic issue. Works perfectly! Also, thank you for making oscilloscope tutorial videos on your channel, I checked them out and they were really helpful!

author: edavid
author_rank: Super Contributor
timestamp: July 29, 2015, 10:34:52 pm
content: One great thing about the 455 is that it is fanless, therefore silent.

author: MistaMun
author_rank: Contributor
timestamp: July 30, 2015, 03:01:52 am
content: Quote from: edavid on July 29, 2015, 10:34:52 pmOh your right, I didn't noticed that. There was a huge piece of heatsink at the back of the unit and I thought it was rather odd looking

author: montemcguire
author_rank: Regular Contributor
timestamp: July 30, 2015, 04:22:53 am
content: Great score! Now turn down the trace intensity before you burn a hole in the screen LOL!!

author: Michaela Joy
author_rank: Contributor
timestamp: August 12, 2015, 01:40:23 am
content: @MistaMun: That scope looks nice, and in pretty good shape. if it's your first scope, then it's a great place to start.I've always been a fan of the Analog O'scope. I have a Tektronix 2465B that I got from ebay. I sent it out and had it repaired and calibrated, and it works great.Best of luck with the new scope.:MJ