For $400 or less, why bother to fix them? None of our color digital scopes, two Rigols and about a dozen Teks, have broken so far.
I used to use a bunch of 7000 series scopes, but most have died by now. Long-term, older tube units, like the 547, are more reliable and more repairable. We do have one 7104 that we use now and then.
But if I want a spectrum analyzer, I can buy a nice new digital one. In inflation-adjusted dollars, they are a lot cheaper than the old Tek plugins were, and work a lot better. And don't need their own wheeled vehicle.
The 7A22 diffamp was cool, but I use an AM502 to front a digital scope and get the best of both worlds.
I do still use 11801 sampling scopes, wonderful boxes. They seem pretty reliable, and used ones cost a few percent of what a new sampler would cost. The sampling plugins for the 7000 series were pretty barbaric.
For me, environmental reasons are number one. If we all follow the unhealthy habit of "chuck it and buy a new one" that is not a good thing. When we moved across the pond we needed a new clock radio that didn't need 50Hz. $9.95 plus tax. One digit didn't work. Drat! Thought about it for 5secs, opened it up, fixed it, done. Took 20mins or so off our Saturday. Driving back to Walmart where they'd just given us a new one would have cost at least 45mins plus a gallon of gasoline. And they'd have chucked the "broken" radio which just had one bad solder joint.
The best thing is, whenever I do that I always learn something new about cost efficient design. Most of all packaging, and with some projects packaging can be >50% of an EE's real work.
[...]
But you can really see the meter spin up when firing up a 547 :-)
Also, I found that while tube stuff is great it becomes harder and sometimes painfully expensive to find NOS replacement tubes. That has brought a nice generator to grief over here because it was built with WW-II era steel tubes.
[...]
--
Regards, Joerg
http://www.analogconsultants.com/
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Use another domain or send PM.
Take a picture or two so you know how the cables go back together. The tantalum caps are behind the left two boards. Much easier if you pull a few of the black rails out of the bottom and stand the scope on the rear. Go in through the bottom and you can remove the bad cap(s). Some suggest just clipping the leads next to the old cap and just soldering the new cap to the old leads. The board is multilayer and very old so pulling the plating out of the holes is easy and ruins the board.
Be gentle around those edge connectors. The plastic covers pop off easily and don't always go back correctly. They are very necessary.
That is a good idea. I was thinking along the same lines, just clipping and soldering some non-tantalums in there. Hoping that the black rails don't break, they feel as if they are totally hardened.
To my surprise the scope decided to just work again. Not sure if the constant pulling and re-inserting of modules did that or what.
--
Regards, Joerg
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For anyone who's looking for a good scope for cheap I'd recommend an Agilent 54825N. 500MHz, 2GSa/s. I think the military has been de-commissioning these for the last year or so. You can usually get 'em for a grand or so on Ebay with a "power up test only, we don't know how to test" etc. I've got five of them right now, that I'll move for 2K or more.
Yeah, it runs Windows, but that doesn't bother me much. In fact, I kind of like it. Controls easily over the network, emails you on a trigger event, and easy to customize.
I'll keep my $900 TDS744--4 channels, 500 MHz, 2 Gs/s, no Windows. When my ship comes in, maybe I'll plump for a TDS694C. One of the world's most beautiful scopes. A bit hard to justify at the moment--for scope stuff, there's not a lot I can't do with a TDS744 and an 11802 with beaucoup plugins.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net
My only problem with that series of scopes (5XX through 7XX) is the CRTs. Eventually they just fade out. The good news is that there's LCD conversion kits that replace the CRT, you can get them for $550 each on Ebay. They look great as well.
Attenuators also seem to fail quite often on the 1GHz and less versions of TDS5XX through 7XX. Running a SPC and getting a compensation error is the usual indicator. They can be re-built with off the shelf components (relays) Just takes a steady hand (2 beers should do the trick), a long tip on the soldering iron, and a microscope.
Thanks, but the 694's 10 Gs/s is the draw. I used to have a 684B, which I liked very well too--the one annoying thing about the 744 is that the display doesn't update until after the next trace comes up. That's a bit irritating when e.g. adjusting the vertical offset during some slow measurements.
SPC is fine so far.
The 744 has a VGA output on the back as well.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net
--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
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At one point I did find a source for the panel and panel controller that would yield a color display. I contacted a Chinese OEM
formatting link
that would sell the panel and controller for $173.
Here's the email:
Thank you for the detail information. Per your request here is what Promate can offer for the G065VN01-V2 (LVDS Interface, LED backlight w/ driver included) + GB Driving Board kit (cables included):
1-99pcs: $173/pc Lead Time : 4-6 weeks This price is based on quantity ordered per Lot.
Thanks and best regards,
Andy Chen Sales Marketing Engineer PROMATE ELECTRONIC CO., LTD.
4F 32, Sec. 1 Huan Shan Rd., Nei Hu, Taipei 114, Taiwan MOBILE: 0988-972-982 TEL: (02)2659-0303 ext.1296 FAX: (02)2658-0954 MAIL: andy_chen AT promate.com
Never followed up with it as I'd still have to have the sheet metal and cables fabricated. I do have drawings of the sheet metal and specifications on the LCD and controller if anyone is interested.
Sometimes yes. The affected scopes I can remember working on off-hand are: TDS520, TDS540, TDS520A TDS524A TDS540A TDS544A TDS640 TDS640A TDS644A. I'm sure I've missed some...
I've cleaned and re-capped tons of those scopes, including a pallet full that Rosenkrantz in Germany shipped to me. A number of them were unrepairable as there were too many open etches and vias. Whoever owned those scopes must have kept using them long after the caps started leaking and the scope failed POST.
I don't recall whether any TDS7XX scopes were affected. At some point they stopped using aluminum electrolytics on the ACQ boards, probably from all the failures that occurred in early scopes. All the TDS7XX scopes I've successfully repaired that were failing SPC needed attenuator re-builds, although some of them were failing SPC for reasons unknown and I was unable to fix.
$2400. Figure about $60 for shipping and insurance anywhere in continental US. Has a nice bright CRT without cranking up the intensity, so it couldn't have seen too many power-on hours. 30 day warranty.
The problem is that the monochrome scopes do not have a color framebuffer.
--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------
I had thought you meant to use the above DIY controller with the color versions of the scope, which is what I was referring to when I mentioned the LCD kit.
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