Used Analog vs New Digital Scope

At my local surplus shop I've found a tek 2465 apparently in good condition for about $700 also a 7704A for $135 with 2 7A13s and a 7B85 $75 each. I have read good and bad about these. My main concern is if I should just buy a new Digital PC card scope for $500. Money is a secondary issue here, I just want something usefull that will last a while. Opinions anyone?

Reply to
Cyber Vagrant
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For durability, Tektronix 500 series can't be beat. Beautiful sharp display as well, which makes the displays on many newer 'scopes appear pitiful.

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Reply to
R. D. Davis

I've got a used Tek 2465A. Best scope I've owned or used. Can't imagine a PC-based scope coming close. So much of the functionality has to do with having really good analog design - you can't make up for it with software.

Reply to
Walter Harley

I looked to avail for a 585A. Although there were some 435, 453,

5440, 465b 100Mhz, and one Gould 1425 20Mhz apparently in good condition. At the moment all I need to do is audio work. In the future I'm planning to building some switched power supplies so I might need a faily fast one then.
Reply to
Cyber Vagrant

snipped-for-privacy@yahoo.com (Cyber Vagrant) wrote in news: snipped-for-privacy@posting.google.com:

2465 was the best analog scope TEK ever made. BUT,the horizontal output IC was prone to fail,and there are no replacements available. $700 is not a bad price for one. 7704A is an older scope,but still a good one.However it uses TEK-made ICs which are no longer available except from parts scopes.CRT should be bright,in focus,and not dim as you increase the intensity control. 7A13 is a good plug-in(PI),but two is not necessary,a 7A26 is a better gen- purpose choice.7B85 is a good Horiz PI.Prices seem OK.

Both of these scopes are better than a PC scope card.If you misconnect a scope lead with a PC card,you can blow your PC.If you want or need a digital scope,get a TDS200 series,or the newer model(TDS2000?)

I would not even consider the old 500 series,unless you need the heat from the tubes to warm your shop,and someone gives you the scope for free.

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Jim Yanik,NRA member
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Reply to
Jim Yanik

On Fri, 28 Nov 2003 15:02:31 -0800, Walter Harley wrote (in message ):

If you decide on the 2465, know that they are a ticking time bomb (I think the 244x series is also effected). The custom IC U400 (I think it is) in the vertical circuit is the first thing to go, and Tektronix is no longer repairing this. Somebody on the 'net advertises replacing this IC for $500-plus.

I have a 2465 and it is great, but I know when that IC goes...

Good luck,

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Reply to
DaveC

That's a nice 'scope. Not too long ago, I spotted one with a note on it that read "free," so, I grabbed it. No, it's not for sale. :-) Good luck finding one; they do turn up here and there, when you least expect them to.

One thing that I forgot to mention, beware of the HP 17xx series 'scopes. Almost 20 years ago, I picked up a 1707B for US$5 at a college surplus sale; it worked great for several years, then, one night I made the mistake of leaving it on overnight. Apparently the HV transformer overheated, and burned out. It took a long time to find a replacement. Actually, I didn't find a replacement HV PSU module for this 'scope until this past year!

BTW, does anyone reading this know which leads to the HV module connect where? Alas, in the course of quite a few years, I lost my notes from when I disassembled that part of the 'scope. Now, I don't know how to connect the new module to the 'scope. IIRC, all of the

17xx scopes use the same HV module, so, if anyone reading this has one and can kindly take a quick peek inside theirs...
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Reply to
R. D. Davis

If you're designing power supplies, I'd avoid a PC scope. A slip of the probe and you can smoke the scope and the PC. Having a scope in your PC sounds like a good idea IFF you need to manipulate the data after acquisition. For most other uses, it's a PITA.

If you've not used a digital scope, find someone who has one and play with it before you buy. I found my Tek TDS540 to be extremely useful when the event doesn't happen often. Like if you want to watch the transformer saturate just before the FET explodes. For most other uses, I find it extremely annoying. I often turn on the analog scope to see what's happening so I'll be able to set up the digital scope for the capture I want. Memory depth is critical. It takes a LOT of memory to be able to view two adjacent pulses at a 25 KHz rep rate...that funny-lookin' trapezoid doesn't give you much information.

The 2465 has an excellent reputation as an alalog scope. I have one for sale here:

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There's also a discussion of the IC reliability and why you might want to be concerned about the serial number of the unit you buy.

mike

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Reply to
mike

Yeah, but what isn't? You could buy a brand new TDS2000, and it's a ticking time bomb too, because when it breaks the only way to fix it is to replace the innards, which probably costs more than buying a new used 2465.

We're all gonna die sooner or later; doesn't mean we're worthless :-)

Reply to
Walter Harley

"Walter Harley" wrote in news:bq9p0k$lf5$0@216.39.172.65:

And once the scope is past the Long Term Product Support period,TEK will no longer have parts or assemblies for the scope,any of the TDS models.And they don't come with component-level schematics in the "service" manuals,either,unless TEK has changed that policy recently. TDS scopes are intended for module-exchange service only.(unless policy has changed)

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Jim Yanik,NRA member
jyanik-at-kua.net
Reply to
Jim Yanik

DaveC wrote in news: snipped-for-privacy@news.individual.net:

No,it's the Horizontal output IC that has a high failure rate.

is the first thing to go, and Tektronix

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Jim Yanik,NRA member
jyanik-at-kua.net
Reply to
Jim Yanik

I read good things about the displays, although I read that cleaning the cams that do some kind a switching is a delicate operation that has to be periodically done.

Reply to
Cyber Vagrant

snipped-for-privacy@yahoo.com (Cyber Vagrant) wrote in news: snipped-for-privacy@posting.google.com:

The cam switches are used on later,solid-state scopes like the 465,475 and

7000 series plug-ins,not the 500 tube-type scopes.They used ordinary wafer switches,with silver-plated contacts.

The 500 series CRTs are at end-of-life status,a gamble that they'll be useable for any length of time.The switches will be wearing out,too.

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Jim Yanik,NRA member
jyanik-at-kua.net
Reply to
Jim Yanik

In article , snipped-for-privacy@privacy.net mentioned...

Why not put a heatsink on the chip now to prevent or delay it from dying in the future?

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Watson A.Name - "Watt Sun, Dar

In article , snipped-for-privacy@abuse.gov mentioned...

I agree 100%. The 541s and their ilk are fine scopes, but they're a waste of power; and the knobs take so much force to turn that if you use it a lot, you'll get callouses on your fingers, or blisters.

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Watson A.Name - "Watt Sun, Dar

Do we actually know that the failure is heat-related? I know a couple of people have suggested doing this, but I don't think I've ever heard why those chips fail in the first place.

Reply to
Walter Harley

"Walter Harley" wrote in news:bqd8up$5rv$0@216.39.172.65:

At TEK we were never told of any specific failure mode,just that the ICs were first in short-supply,then "internal use only",then not available;supply depleted.

ISTR it was a bad production run,and the high failure rate was not known until the ICO/Hybrid manufacturing unit was sold to Maxim and no changes were able to be made.

But a HS would not do any harm. (as long as it does NOT contact the cabinet.)

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Jim Yanik,NRA member
jyanik-at-kua.net
Reply to
Jim Yanik

In article , snipped-for-privacy@cafewalterNOSPAM.com mentioned...

Well, my thinking is that the cooler the chip, the slower the degradation from whatever reason. So if you cool the chip ten deg C, it should last twice as long since the chemical activity doubles with every ten deg C.

But then I have no idea what's causing the problem. It may have nothing to do with chemical activity.

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Reply to
Watson A.Name - "Watt Sun, Dar

Fer instance, maybe the vibrations eventually break the little tiny wires in there.

I think I'll put a heat sink on mine...

Reply to
Walter Harley

Interestingly, although your page claims that the 155-0241-02 variation of U800 is more durable than previous ones (presumably 155-0241-01), a Google News search shows about the same number of posts from users asking about both part numbers. I wonder if the production quantities were similar?

From what I can tell based on the service manual, this chip really isn't anything all that special. It looks like an ordinary RPTV video driver chip could replace it, if you made provision for the variable-gain feature needed for the X10 magnification feature. There is plenty of room under the motherboard for an aftermarket kludge^h^h^h^h^h^h assembly, if anyone were inclined to develop one.

I just sold a 2467 on eBay with the -01 part number with 27,000 hours on it, still going strong. My own 2467 has over 12,000 hours on a -02 part. So they definitely don't ALL die an early death.

-- jm

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Reply to
John Miles

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