Repair broken Tek 485 or buy good used 2465/A/B?

snipped-for-privacy@slack.com (David DiGiacomo) wrote in news: snipped-for-privacy@corp.supernews.com:

how much "high performance" do you need for audio,tube amps?

250Mhz is overkill. A T922 (15Mhz)would suffice,and be far more reliable than a 485. No OOP TEK-made ICs,either.

--
Jim Yanik
jyanik
at
kua.net

Fred Bartoli wrote in news:474f0e13$0$13261$ snipped-for-privacy@news.free.fr:

Ignorant beancounters and overpaid upper management. They thought they could sell off the ICO/hybrid division,and then buy the same parts from the new owner,but Maxim decided TEK was not buying in enough volume to make Maxim happy,and forced a last-time buy before shutting down the production of TEK ICs/hybrids.

They didn't "lose" the technology,they sold it off.

--
Jim Yanik
jyanik
at
kua.net

Well, point being I already have the 485. BTW, I got this 485 gratis from a friend who was hoping to use it but couldn't find the time over the years. But then it died shortly after I received it from him.

My original query was based more around the thought "Should I put money into this 485?". Or if it's too much hassle/cost to fix it would I be better served (on the repair person's advice) to sell/trade it in for a 2465 or another 485 he has (with the possible notion that I may "grow" into whatever I end up with)...

My apologies for apparently having caused more excitement than I had planned on.

There's no excitement. :)

It won't be cost effective to have it professionally repaired.

You have nothing to lose and all to gain by finding the shorted cap(s) and replacing them, or all of them. A decent DMM is all you need.

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Well using a 485 for that sort of work is sort of like using a McLaren F1 to go buy groceries. It'll do the job just fine, but there remains a huge amount of untapped capabilities.

That said, it'll do as fine a job as as anything else you can find, and as old as it is, the price should be reasonable.

Or someone may well be willing to trade him a good working lower end scope for the as-is 485. I would if I had one, but my 465 meets my needs.

Well, point being I already have the 485 which I got free from a friend who was hoping to use it but couldn't find the time over the years. But then it died shortly after I received it from him.

My original query was based more around the thought "Should I put money into this 485?". Or if it's too much hassle/cost to fix it would I be better served (on the repair person's advice) to sell/trade it in for a 2465 or another 485 he has (with the possible notion that I may "grow" into whatever I end up with)...

To which another poster in a cross-post has replied that it wouldn't be cost effective to repair the 485 implying that I could do the work myself...

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@s8g2000prg.googlegroups.com:

the 485 power supply is a very tricky one;it's a series-resonant switcher with several control loops.it's very easy to make the PS -worse- than it was before you tried to fix it. It's also complicated by the terrible access to parts of the PS,and the inability to isolate scope circuit sections from the PS.

You definitely need a service manual before starting in on it.

--
Jim Yanik
jyanik
at
kua.net

OK, I have a question for the group. Gonna deviate a little here from the original post...

What is a "Storage Oscilloscope"? Is there anything it can't do that a normal oscilloscope can (for mostly audio purposes)?

I have a chance to get a Tek 434 locally. Anything I should know about it? Any big problems with it?

Also, would the probes be compatible between the 485 and the 434?

Thanks, Chris

OK, I have a question for the group. Gonna deviate a little here from the original post...

What is a "Storage Oscilloscope"? Is there anything it can't do that a normal oscilloscope can (for mostly audio purposes)?

I have a chance to get a Tek 434 locally. Anything I should know about it? Any big problems with it?

Also, would the probes be compatible between the 485 and the 434?

Thanks, Chris

Usually a 'storage' scope will allow you to save a trace that is one time and keep it displayed for a long(er) period of time. That is it won't fade out.

There are some downsides, but generally a storage scope will do all that a regular scope will do, and then some.

Most scope general purpose probes are compatible. Speciality probes are a different issue however. When I say compatible, we're talking an industry standard and often probles from other makes of scopes will work just fine with whatever you have. You will have to adjust the comphensation for a 10x probe, and sometimes they don't comphensate properly for a diffent scope, but generally you are OK.

(I use a storage scope for my general purpose work...)

OK, I have a question for the group. Gonna deviate a little here from the original post...

What is a "Storage Oscilloscope"? Is there anything it can't do that a normal oscilloscope can (for mostly audio purposes)?

I have a chance to get a Tek 434 locally. Anything I should know about it? Any big problems with it?

Also, would the probes be compatible between the 485 and the 434?

Thanks, Chris

snipped-for-privacy@gmail.com wrote in news:cdb4bcb6-0826-4a3f-a41b- snipped-for-privacy@e10g2000prf.googlegroups.com:

the TEK 434 is a 25 Mhz bistable storage scope;the CRT phosphor can store a captured waveform for a short time;the CRT has flood guns that keep the stored trace illuminated.

First Q would be price? how much for the 434? They are not worth more than a few 100 USD.

2nd worry is the CRT condition; the storage flood guns wear out and no longer maintain writing speed,and the 434s are old enough to worry about the non-storage trace too. 3rd;the 434 has a very wierd power supply,and the HV is prone to arcing and zapping the Z-axis board.the 434 HV is not something you can rebuild. 4th;434 has several TEK-made ICs,all out of production(OOP).

IMO,a 434 would not be a very wise buy.

--
Jim Yanik
jyanik
at
kua.net

snipped-for-privacy@gmail.com wrote in news:2fda6ec1-272c-4e89-b6b2- snipped-for-privacy@w40g2000hsb.googlegroups.com:

oh,yeah!

IMO,skip the 434.

I suggest you buy a 2213,2215,"A" versions of those scopes,2235,2236(100Mhz),or a working T922(15Mhz) or T932/935(35Mhz). The T900 series are very inexpensive,simple scopes. I have a 2213 myself.(2 Ch,60Mhz BW)

422,453,454 are all OLD scopes and a crapshoot WRT the CRT and switch life. People really like them,though.

465's are a great scope,LOTS made,plenty of "parts scopes" available,but still getting old.

AVOID 2300 series scopes. Avoid 200 series scopes. Avoid 5000 series scopes. Avoid 7300,7400,7500 series scopes.

7600 scopes are good,7704A,and 7904 are great. A 7603 with 7A26 and 7B53A plugins is a good combo.

--
Jim Yanik
jyanik
at
kua.net

Ante up and buy a brand new scope. Or a used refurbed late model in support one from a real supply house with a cal cert.

The old Teks are a bargain until the first unobtainable part fails. The problem is the same parts fail and therefore the supplies are exhausted. You wind up swapping out parts from a scope junkpile of carcasses you can't bear to chuck out since they are mostly good but one tiny weensy thing-okay, the jug isn't so tiny-and there are no more.

From a USER standpoint the best scopes ever made were the last analog Teks-22xx and 24xx B models with cursors, soft knobs, and "all mod cons" and a real electrostatically deflected CRT. From a repair standpoint they are a disaster. (There were also the aborted fetus TAS models which are dogshit even when working.)

The best analog scope tech TODAY, is far and away Iwatsu with their converter tube which is a small CRT with a CCD sensor in the end instead of phosphor screen. Their scopes are well made but the user interface is not as good as classic Teks.

New analog scope choices today come down to Iwatsu, Hameg, maybe Hitachi. Sencore still makes their overpriced shitbox and cheapo third tier models are available too.

The Lecroy people proved this false when they were selling Iwatsus here. The converter tube Iwatsu does everything a 485 does, but backwards and in high heels, plus gives you VGA and digital image storage.

If it can be fixed cheaply fine, but understand it's an asset that has a fixed and not well known finite life ahead of it. If the tube or any of half a dozen other things goes it's like, well, it's worse than an antique car with a shattered engine block-you can't swap in an incorrect but close looking engine. Tek made a cornucopia of CRTs each unique to one or two models.

Hi Jim,

Another reason why I should avoid is due to lack of a feature. In my research, I see no ability to check for phase shift ("X-Y") between two signals. My 485 has this abillity with the "X-Y" button, which I don't see on the 434. Right?

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@e25g2000prg.googlegroups.com:

well,I can't recall specifically if it does,but I believe it does. I think you have to put the time/div switch into X position,then use Ch2 for it's input.I'd have to see a front panel pic to be sure.

--
Jim Yanik
jyanik
at
kua.net