Running time for analog Oscilloscope - Page 1
Forum section: electronics / testgear

author: CountParadox
author_rank: Contributor
timestamp: January 08, 2015, 12:21:03 pm
content: Hey guys!!Got my first Oscilloscope the other day :)a Hitachi V-212 for $50 + $25 p&h from gumtree,I'm wondering if there's a maximum time I can have it run for? :)for example, would it be safe to leave it running over night if i fall asleep while using it ? (staying up to ungodly hours trying different musics and tones and such with it c: )or is it something that I want to use for no longer than the time I need it for?My uncle told me to keep the brightness not too high, to avoid burn in which makes sense, but brings forth another question I have of how does CRT burn in ? D:Thanks in advance c:Also, See photo of what I believe is calibrated :Damidoingitright?

author: Whales
author_rank: Super Contributor
timestamp: January 08, 2015, 12:33:24 pm
content: CRT burn-in could be an issue, depending on what signals you are using and how they will be displayed:https://en.wikipedia.org/wiki/Screen_burn-in. Also make sure your leads can't fall out while you are asleep -> flat lines or (worse) dots keep the same phosphor lit.Safety of running it unattended: I imagine all mains equipment is designed to handle being left on indefinately BUT I would not trust it without a good internal inspection (at minimum) to make sure nothing looks suspicious or is caked in dust/flammable insect lasagne.Cathode ray scopes (along with CRT TVs and monitors) have somerather large hidden dangerswhen opened, so please research "discharging the tube" and "discharging power supply capacitors" before opening it up.

author: CountParadox
author_rank: Contributor
timestamp: January 08, 2015, 02:41:17 pm
content: thanks for your reply c:I'm more concerned about the scope damaging itself, eg, a limited lifetime i don't want to waste ^^;but good idea on the checking for dust and things,ill clean it out (if needed) with compressed air maybe when i get around to properly cleaning the thing up. I want it mintIt is a fan-less design which is nice, and apparently portable, it has a handle on the side..

author: DanielS
author_rank: Frequent Contributor
timestamp: January 08, 2015, 03:12:21 pm
content: A common thing to watch out for in all old equipment is failing electrolytic and tantalum capacitors: even the best of them may start to show their age after a decade or two.If you really want to leave the scope on 24/7, you probably want to reduce beam intensity to minimize burn-in if it is going to display repetitive signals for long periods of time. Lower intensity also facilitates sharper beam focus, which helps if you want to see smaller waveform details.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 08, 2015, 03:56:48 pm
content: Lifetime is usually limited by CRT age (of the phosphor and cathode) and electrolytic capacitors (which dry out over time).Good instruments are usually upwards of 5 years use (~10k hr continuous operation). Example: I got about that out of my Tek 475, which runs the cathode a little hot (design flaw) and therefore the beam gets dimmer over time, until even at maximum settings, it's useless. I replaced the CRT and it was good for a few years, until the electrolytic capacitors finally needed replacement (that they survived over 30 years is pretty remarkable). It still works today, though because of other age related problems (bad attenuators, switches), and having a DSO, I don't use it very much.Tim

author: KJDS
author_rank: Super Contributor
timestamp: January 08, 2015, 04:57:15 pm
content: I thought that Dave preferred running with digital scopes

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2015, 08:15:15 pm
content: Don't leave it running excessively.Go get a coffee is fine, but longer dim the trace or de-focus it.The Electron beam will degrade the phosphors on the inside of the screen if left too bright and/or left adjusted on 1 vertical position for extended periods.Then the trace will be dimmer in these areas.Used with this knowledge, it should last for years until some other component failure.The HV will attract dust electrostatically and a blow out is a good idea from time to time.

author: DanielS
author_rank: Frequent Contributor
timestamp: January 08, 2015, 08:29:52 pm
content: Quote from: KJDS on January 08, 2015, 04:57:15 pmDigital scopes run circles around analog for tons of uses and features but analog still has its place for some applications - analog scopes have practically infinite horizontal and vertical resolution, none of that silly digital sampling, quantization noise and display scaling/filtering business!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 08, 2015, 11:23:57 pm
content: Quote from: DanielS on January 08, 2015, 08:29:52 pmYeah, it's not like pushing in that VERT BW button to the full 200MHz+ makes the trace thicker or anythingApplies to digital all the same -- my TDS460 shows around, what is it, 600uV RMS noise at full BW I think. Which goes right down at reduced BW, Hi-Res mode or with averaging. Same reason high-BW scopes (and SDR, and..) rarely offer lavishly high bits, because there's more analog noise (at 50 ohms input, or anything else) than quantization noise. At reduced analog and digital BW, noise goes down and ENOB goes up (usually by oversampling and filtering). In other words, an 8 bit 1GSa converter is equivalent to 12 bits at 62.5MSa, and so on.Tim

author: CountParadox
author_rank: Contributor
timestamp: January 10, 2015, 11:21:21 am
content: Hello again everyone following!Today I was viewing different songs through it enjoying myself looking at the waveforms in them, and the CRT went off after an hour or so,I after checking i hadn't messed something up config side, I turned it off and let it rest for about 20 minutes, and It was working fine again,Did I overheat it or something ? D:Have placed a fan at the back blowing air over it for now, if it IS overheating I might look at modding a small PC fan into it somewhere (No idea about powering it or whats inside yet, I have the manual to skim over and if i do put one in ill document it here!)The casing didn't feel unusually warm, but today was pretty warm

author: EEVblog
author_rank: Unknown
timestamp: January 10, 2015, 11:27:27 am
content: Quote from: CountParadox on January 08, 2015, 02:41:17 pmNope. In theory better to leave it powered up actually, less stress on some parts. But don't go doing that just for the sake of it!The V-212 is a lovely little scope, always had a very nice sharp trace, enjoy!

author: nctnico
author_rank: Super Contributor
timestamp: January 10, 2015, 02:42:45 pm
content: Quote from: T3sl4co1l on January 08, 2015, 11:23:57 pmThat works if there is enough noise for oversampling to work. If there isn't (for example when you limit the bandwidth) you can get really funny waveforms.Anyway, I don't see the use to leave an analog scope switched on when you are not looking at it. With a DSO you could set it up to trigger on a spurious event and take a coffee break or nap.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 11, 2015, 03:55:43 am
content: Quote from: EEVblog on January 10, 2015, 11:27:27 amYes & no-----waveform monitors were left on continuously,& their CRTs lasted twenty years or so.If your 'scope has a linear supply all is OK,but there may be a hidden problem if it uses an early type SMPS.Some of these use a high value resistor from Mains Active to give the oscillator a starter "kick".Once it is running,all is well,but if the resistor went very high in value after the last start,the SMPS won't restart after ,say,a Mains failure.It was "received wisdom" at the TV Studio I worked at,to leave everything "on"at all times------a reasonable idea in the tube days,where gear took hours to stabilise,but not necessary with Solid State.One one occasion,a power failure left us with four Picture Monitors out of seven in Master Control as non-starters.Not great,when you are the bunny who has to find & install replacements ASAP!For this reason,I would suggest turning your 'scope off from time to time,so that if it doesn't restart,you are in a controlled situation when it fails & not have the failure happen when you most need it.

author: TunerSandwich
author_rank: Frequent Contributor
timestamp: January 11, 2015, 08:39:19 am
content: If components are going to fail, they are usually going to fail at power up. Unless the scope is generating some ridiculous current draw, it's fine to leave it on....just turn the intensity all the way down (plus holdoff all the way up, if intensity doesn't fully dim the trace).It's better for parts that are still in spec to remain powered on.....let them settle in and stabilize, and then check all of your rail voltages and your total power draw. They were designed to be left on. If something does fail while it's on, the likely hood of catastrophe is far less than a large inrush current failure, on cold start-up.Also don't leave it running with large input signals, via low impedance termination (which you shouldn't' be doing anyhow)P.S. also try and replace all the electrolytic and tantalum caps....if the CRT goes, it's not worth fixing, but the caps are easy and cheap....throw some temp rated caps in there and it'll possibly go another 20 years