Oscilloscope Poll! How many do you own?

[diif]

Re: Oscilloscope Poll! How many do you own?

Cheers stj, would those be the x10 I see indicated with probes ?
I figured I'd use it for measuring ripple of caps and signals on laptop motherboards.
I'll sleep on it and maybe put in an offer tomorrow.

[stj]

Re: Oscilloscope Poll! How many do you own?

if you dont mind a risk, there is a 50MHz tektronix D755 for about £5 up tomorrow.
sold as untested - looks like it's been in a loft for years.
it's a good scope though - a rebadge of a telequipment D83 with a nice big screen.

[eccerr0r]

Re: Oscilloscope Poll! How many do you own?

I've seen a lot of "parts or repair" scopes on ebay. Have to watch out for them...
I've already made two repairs on my ebay Tektronix 2440 DSO (well, three, the third one was an easy one already known from ebay description). Both required significant debug effort, and without my other scope I probably would have had to just leave it as a 10MHz DSO.

And it still won't ever play Beams of Light because its XY mode is a primitive display system, though it will indeed resolve 300 MHz signals by interpolation...

[stj]

Re: Oscilloscope Poll! How many do you own?

the D755 has XY+Zinput and is modular - i have the D83 badged one here!
i have the schems too.

[eccerr0r]

Re: Oscilloscope Poll! How many do you own?

IMHO: if you like repairing things, you should get a known working scope. Your second scope can be a potentially nonfunctional one. I think doing it the other way around is more frustrating...

[Compgeke]

Re: Oscilloscope Poll! How many do you own?

I have three scopes, only one working.

Tektronix TDS684B: Works fine, use it with two P6138 probes.

Tektronix TDS420: Got it off freecycle with the P6138 probes after it went bank. Needs a recap + some resistors replaced and who knows what other damage. I'd rather get someone else to fix this some day, I don't have stuff for SMT (and I hate SMT).

Heathkit IO10: Old 10 MHz (or 5? I dunno) tube 'scope. Also needs a recap and while I could do it, it's all point to point and a complete disaster inside.

Tested it on my Tektronix scopes - XY sample rate on my DSO is insufficient, but the analog shows it just fine. Funny how compression shows up as fuzziness...

My TDS684B won't even do it, and that was a pretty high end 'scope. I just get a tiny blotch of fuzzy stuff rather than graphics.

[diif]

Re: Oscilloscope Poll! How many do you own?

if you dont mind a risk, there is a 50MHz tektronix D755 for about £5 up tomorrow.
sold as untested - looks like it's been in a loft for years.
it's a good scope though - a rebadge of a telequipment D83 with a nice big screen.

Yes, I spotted that one thanks, it's in my watch list along with a couple more.

[eccerr0r]

Re: Oscilloscope Poll! How many do you own?

Tektronix TDS420: Got it off freecycle with the P6138 probes after it went bank. Needs a recap + some resistors replaced and who knows what other damage. I'd rather get someone else to fix this some day, I don't have stuff for SMT (and I hate SMT).

It was sort of the reason why I got the 2440 (and risked it as it was not functional), in hopes that I wouldn't have to do SMT surgery (though now I do see some SMT in it... not many...) After working on it I feel like I've become some sort of expert on it now :p

My TDS684B won't even do it, and that was a pretty high end 'scope. I just get a tiny blotch of fuzzy stuff rather than graphics.

Yeah exactly what the (~10 year older) 2440 does with it, at the time it was Tek's "high end DSO". I think stj has my only example on why XY mode is actually useful, I think Tek knew that, alas with people doing stuff like Beams of Light, people are expecting this mode of operation... I think XY mode lost its usefulness when dual channel scopes came on the scene. XY was only useful on 1-channel scopes and carried on just because "the old one did it...why not this newfangled one?"

Not sure what to say about it, unless someone comes up with some more examples why XY mode is useful.

That being said I still want to get a raster image to show up on my 2465 in XYZ mode Needs external circuitry however of course.

[juliadream]

Re: Oscilloscope Poll! How many do you own?

I've been watching people bidding up broken non working cro's on ebay to stupid prices recently. Couple of old Iwatsu 20MHz ones that honestly aren't worth more than £40 each fully working went dead as a Taro Kun could be.. for £85 plus £25 shipping.. really? Mine is going to cost me all of about £20 for caps and various high value resistors.. so total £25 .. not bad.. might sell it on for a better one at some point, but I don't need the speed.. will convert a surplus laptop into a faster one using some kit and software if I ever do need something like that.

Mostly I find with laptops etc you only need to check the rtc and bucks.. they don't do more than 10MHz.. dual beam is nice with audio gear for checking phase shift in tone control networks etc.. otherwise..

Until recently I had a 1Mhz Industrial Magnetics cro.. built April 1944.. sold it for the tubes to an audiophool.. hope he liked the worn out EF36 and L63 tubes.. borderline they were.. Scope worked but was more trouble than it was worth to keep running.. some of the cash from that went in my new antique restoration project.. as much for fun and memories as a serious piece of my toolkit. I don't get why people will pay such high prices for what is in effect obsolete equipment..

Hey stj .. was that tektronix the one with the impossible to replace eprom chip.. I know there is one model on the avoid list due to impossible to replace part.. not so much the component as the eeprom file that's needed to flash the replacement

p.s .. even if I saw it there is no point adding to the competition.. I'm in the market myself for busted non working stuff.. might have had a punt at a £5 tek .. but will leave it.. cos I'm nice like that.. lucky I looked in and saw there was other interest or I might have bashed in what I consider a "reasonable" max bid.. and theres no point in forum colleagues bidding against each other is there

[stj]

Re: Oscilloscope Poll! How many do you own?

nothing digital in the D755.
it's a 100% analog modular scope.

by modular, i mean the timebase and input sections pullout from the front on rails - so you can fit upgrades.
although i think that one has the best in it already - unlike mine.

it's a big fucker btw - real nice screen size!

[Compgeke]

Re: Oscilloscope Poll! How many do you own?

Actually I take back what I said about oscillofun and such, it does work but without vector XY (only dot) it looks terrible. Also can't move stuff around in XY.

Upside-down Oscillofun (no idea why it's flipped)
https://www.youtube.com/watch?v=dJaynJSSZOE

Beams of Light with the XY flipped:
https://www.youtube.com/watch?v=KzfV1j1r4ZQ

[stj]

Re: Oscilloscope Poll! How many do you own?

flip it back by inverting the inputs.
a lot of scopes have a button to do that.

[eccerr0r]

Re: Oscilloscope Poll! How many do you own?

That's a lot better than what I'm getting on the 2440... just shows up as blob in the center.

Actually my 2465 is one of those unobtanium EAROM... however I backed up the contents of the EAROM by hand (it's only 1400 bits) so when it does go, I can get it back to exactly how it was, whether I have to build a EAROM emulator or obtain a EAROM from somewhere. Found some data to figure out the checksum and looks like my hand recording passes checksum and I'm good to go. Technically speaking even if I lost the contents of the EAROM, the problem is just calibration. If the scope can be calibrated normally, there's no problem with the loss of EAROM data.

A lot of the scopes from that era have NVRAM problems, the main problem with my 2440 when I got it is that the NVRAM lost data due to age. I jury rigged another battery in it and manually did cal (the 2440 cal isn't nearly as tough as analog scopes since it is a digital scope) and I'm good for another 5 years or so, worst case. I found it amusing that worst case the original *SOLDERED* battery would last 3.5 years, and the longest warranty on these scopes was ... 3 years...

[Compgeke]

Re: Oscilloscope Poll! How many do you own?

One disadvantage to my TDS684B is it will have NVRAM problems eventually, however it's a Dallas module. Replacing that means hacking up the top and soldering a battery onto it since replacements aren't made anymore.

Some day I need to open it up again and see what the chip number is, maybe my EPROM programmer can dump it.

[eccerr0r]

Re: Oscilloscope Poll! How many do you own?

Yes those Dallas modules plague all the Tek computerized scopes. I got lucky in respects, both my 2465 and 2440 do not have the Dallas modules. The 2440 was later modded with the DS modules, and the 2465A/B uprevs have the Dallas modules.

It would be a good idea to dump them when you can though if you can calibrate your scope, it might not be worth it to do it. It's risky to remove them as one false move and the module has amnesia...

[Compgeke]

Re: Oscilloscope Poll! How many do you own?

The TDS420 actually doesn't use Dallas modules, instead it has 3V BR-1/2A batteries. They're both around 2.99V but I'll replace them some day. Even if I don't plan on recapping right away (just alcohol baths now and then) it'd be nice to keep the calibration intact.

http://i.imgur.com/ivykPWm.jpg

[eccerr0r]

Re: Oscilloscope Poll! How many do you own?

The 2440 was annoying, needed a 3.6V battery. I got a 14550 LiSOCl2 cell which holds about 66% more than the original soldered-on cell... put it in a socket and stashed the battery remotely.

I initially tried swapping the cell for 2 alkalines and 3 alkalines, both of which made the scope unhappy. The 3V might be easier to mod for alkalines.

[stj]

Re: Oscilloscope Poll! How many do you own?

ER1400 rings a bell, i think some arcade stuff may have used it - so i may have a few spares!

this can read and write them.
http://www.ic-prog.com/index1.htm

[eccerr0r]

Re: Oscilloscope Poll! How many do you own?

Indeed yes this chip is used in many arcades of that time period. 100 x 14 (weird!!!) is not a lot of storage but it it's enough for more than 10 sets of AAA and 99999. I've been thinking about either building the circuitry to read/write them but decided to postpone when I found another way to read it (because it's soldered into the board, removing it is risky). I'll remove it when I have no options and need to stop it from saying FAIL 04 meaning it failed the EAROM selftest.

The nasty part of the ER1400 is that it is not TTL compatible - it uses MOS level signals and requires a -35V supply and thus level shifters to be compatible with TTL.

I don't think it's a reason to avoid the 2465 scope, of all the analog features I've seen out there on scopes, this has pretty much all of them and fairly high bandwidth as well.

[eccerr0r]

Re: Oscilloscope Poll! How many do you own?

Speaking of the Heathkit IO10, that is a gem. So what if it's point to point, you can get at pretty much any part in the system, and likely you can keep on repairing it for a very very long time, until we run out of vacuum tubes...

Saw the manual:
3" CRT
Bandwidth: DC to 200KHz (but at -2dB not -3dB so it should be a bit higher than 200KHz)
Input impedance: 3.6M ohms
Sweep from 5Hz to 50KHz - no triggers, but blanks on retrace

I recall having a tube scope that did not blank on retrace, no triggers, and the sweep wasn't even linear... now that was really nasty to use. Luckily I didn't need to use it...