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Thread: fixing up old lab equipment: TEK 7613

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    fixing up old lab equipment: TEK 7613

    I got a giveaway TEK 7613, friend had it in his closet since 1990 or so, and his wife made him toss it or give it away.
    Thought would be cool to learn (re-learn) to use for audio stuff.
    it powers up, and shows a decent trace. The phosphor doesn't look to be burned badly.

    I saw a thread on a blog a while ago, some guy had an old TEK scope that he could not get electrolytic caps for any longer, it was the size of that cap that was the problem. he's a guru like you guys, made some circular circuit boards, two pin holes fit new cap lead spacing, and he soldered in two pieces of leads to fit the machine.

    Cool, project. Curious, that the PS caps are most likely leaking. Would be be worth it to try something like that on this scope? Anyone try this on their old scope or other lab equipment?

    if I continue to use this scope, and the caps are bad, what problems would it cause?

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    The only good solid state amp is a dead solid state amp. Unless it sounds really good, then its OK.

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    As Enzo would say (and I heartily agree): Why repair something that isn't broken? (I also own a couple of rather old Tek scopes types 547 and 453, no repairs done yet).

    Bad PS caps would make your trace move quickly up and down.

    Just enjoy using your scope and actually seeing signals. (And do read the manual to find out about trigger and storage options, learn how to read frequency.)

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    Last edited by Helmholtz; 02-17-2020 at 08:51 PM.
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    Supporting Member nevetslab's Avatar
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    Quote Originally Posted by mikepukmel View Post
    I got a giveaway TEK 7613, friend had it in his closet since 1990 or so, and his wife made him toss it or give it away.
    Thought would be cool to learn (re-learn) to use for audio stuff.
    it powers up, and shows a decent trace. The phosphor doesn't look to be burned badly.

    I saw a thread on a blog a while ago, some guy had an old TEK scope that he could not get electrolytic caps for any longer, it was the size of that cap that was the problem. he's a guru like you guys, made some circular circuit boards, two pin holes fit new cap lead spacing, and he soldered in two pieces of leads to fit the machine.

    Cool, project. Curious, that the PS caps are most likely leaking. Would be be worth it to try something like that on this scope? Anyone try this on their old scope or other lab equipment?

    if I continue to use this scope, and the caps are bad, what problems would it cause?
    I forget the details on the 7613. I have a R7623A and a 7633 (that one here in the shop), along with a couple 7834's...all storage scopes. Isn't the 7613 also a storage scope mainframe? I haven't yet pulled the power supply module out of this 7633 scope, though I do need to address it at some point. as Helmholtz stated, you will see vertical modulation of the waveform. The more severe, the worse it is. Mine does show a little bit. Back when these scopes were in production, Tek was using what is no longer a common capacitor package....having the four ground flaps and solder terminals like found in older tube amps. When I get around to replacing those caps, I too will be making the special fiberglass mounting boards so I can use current technology radial electrolytic caps and get these back to prime condition

    I've been using the 7000 series scopes since the military and industries moved on to the 11,000 series scopes and beyond, so there was a great selection of mainframes and plug-ins available. You can still find them, of course, though now further aged, but, real beauties as far as quality standards go. 7618 or 7618A was the standard dual trace plugin for that, along with the faster 7626A. 7613A is a great 100MHz differential comparator pluging, 7622 is a 1MHz differential plugin with 10uV/Div thru 10V/Div sensitivity, another gem. 7653A is the 'standard' time base plugin. Many other plugins avaialable, including a curve tracer 7CT1.

    You've inherited a gem! I love my Tek scopes. As long as you have the bench space for their depth, you've got a wonderful work horse.

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    Quote Originally Posted by nevetslab View Post
    I forget the details on the 7613. I have a R7623A and a 7633 (that one here in the shop), along with a couple 7834's...all storage scopes. Isn't the 7613 also a storage scope mainframe? I haven't yet pulled the power supply module out of this 7633 scope, though I do need to address it at some point. as Helmholtz stated, you will see vertical modulation of the waveform. The more severe, the worse it is. Mine does show a little bit. Back when these scopes were in production, Tek was using what is no longer a common capacitor package....having the four ground flaps and solder terminals like found in older tube amps. When I get around to replacing those caps, I too will be making the special fiberglass mounting boards so I can use current technology radial electrolytic caps and get these back to prime condition

    I've been using the 7000 series scopes since the military and industries moved on to the 11,000 series scopes and beyond, so there was a great selection of mainframes and plug-ins available. You can still find them, of course, though now further aged, but, real beauties as far as quality standards go. 7618 or 7618A was the standard dual trace plugin for that, along with the faster 7626A. 7613A is a great 100MHz differential comparator pluging, 7622 is a 1MHz differential plugin with 10uV/Div thru 10V/Div sensitivity, another gem. 7653A is the 'standard' time base plugin. Many other plugins avaialable, including a curve tracer 7CT1.

    You've inherited a gem! I love my Tek scopes. As long as you have the bench space for their depth, you've got a wonderful work horse.
    Good deal, thanks! Yes, I have repurposed some old kitchen cabinets, and section of the old countertop for a workbench in the basement. The reason this scope has been sitting for 1 1/2 years is that didn't have the space upstairs (in my tiny office/practice room) to set it up. It just fits front to back with a little room for cables downstairs.

    I haven't used it enough to know if it has the trace wiggle. I just powered it up, let it warm up a bit, and ran some audio from my guitar amp with a sine wave input, the scope across the speaker terminals. I got the frequency and it looks pretty close for not having been calibrated since Ronald Reagan was president.

    0 Not allowed! Not allowed!
    The only good solid state amp is a dead solid state amp. Unless it sounds really good, then its OK.

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    Quote Originally Posted by Helmholtz View Post
    As Enzo would say (and I heartily agree): Why repair something that isn't broken? (I also own a couple of rather old Tek scopes types 547 and 453, no repairs done yet).

    Bad PS caps would make your trace move quickly up and down.

    Just enjoy using your scope and actually seeing signals. (And do read the manual to find out about trigger and storage options, learn how to read frequency.)
    That's me, can't leave well enough alone, thanks. I just didn't know if the caps got bad enough if it would blow something out that I definitely would not know how to debug. And I don't have a second scope to check out this one!

    0 Not allowed! Not allowed!
    The only good solid state amp is a dead solid state amp. Unless it sounds really good, then its OK.

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    Quote Originally Posted by mikepukmel View Post
    I haven't used it enough to know if it has the trace wiggle. I just powered it up, let it warm up a bit, and ran some audio from my guitar amp with a sine wave input, the scope across the speaker terminals. I got the frequency and it looks pretty close for not having been calibrated since Ronald Reagan was president.
    I've found their 'relative' calibration VERY STABLE over the years. I did pick up a plugin extender which allows periodic adjustment of the vertical balance in the dual or single-trace plugins, but usually, they hold that pretty well. The tell-tale sign is the switch that give you phase reverse of the lower trace. If it's DC location goes a good distance away from center, then trimming becomes helpful, though won't prevent you from using it unless gross.

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