first think to do when plugging in a very old 'scope

[J M Fahey]

I do have a 250 watt light bulb limiter setup, though, could use that for the first "fire up".

Then you have a "non limiter"

All it will protect is your home fuse

250W into a load has tons of burning power, even exploding power if you, say, have a shorted diode or upside down capacitor or have set amp to 110V on a 220V line or ......

Start way smaller, such as 40/60W , until you are reasonably certain things are fine.

Takes a lot of the edge out of the prayer "I hope it doesn´t blow! ... I hope it doesn´t blow! ... I hope it doesn´t blow! ... "
It also makes less necessary to keep a fire extinguisher nearby.

and then suddenly the current draw will avalanche when nudged up a little further. Things happen quickly - sometimes too quickly to catch. A bulb will light up much quicker than my DMM/eye/brain/hand response in turning the dial back on a variac.

That´s the point, the equipment reaction time.
I mean MY "equipment", specially the 65 y.o. wet CPU.
Can´t call micro-processor a soft wet worn thingie weighing about 3 pounds with a clock speed of 50 to 100 Hz ... on a good day

[mikepukmel]

Thanks everyone. I have 60 watt bulbs, no 40's. Looking up that prayer book I had when I was a kid. I found the manual and it has parts lists for some of the boards, not all it seems. Would be a challenge for me to find the power supply in this beast! My hopes are not so high, it was a freebie. Have to wait till the Mrs is out of the house before I plug it in, in case is smokes something (she gets all worried when stuff smokes up).

[mikepukmel]

My eye-> brain -> hand reaction time isn't all that great. maybe I should move this initial startup project into the back yard, in case it goes fukushima.

[mikepukmel]

best way to determine of electrolytic caps are bad

What's the best way to determine if an electrolytic cap in this old chassis is bad? Do I have to remove it and put it on a tester, or is there some other way, e.g. look at AC voltage vs DC voltage with a meter?

[Enzo]

First we want a reason to think it is bad.

Then we look at what the cap is supposed to be doing in the circuit and ask if it is doing that or not.

[Mick Bailey]

And to that we come down to the definitive manual on scope troubleshooting. But first you need a fault to troubleshoot - chances are the scope is fine. (direct link to manual):

https://www.google.com/search?source....0.nEojHzy7dfQ

[mikepukmel]

And to that we come down to the definitive manual on scope troubleshooting. But first you need a fault to troubleshoot - chances are the scope is fine. (direct link to manual):

https://www.google.com/search?source....0.nEojHzy7dfQ

Thanks, awesome link, downloaded the manual, reading now. . . . (Haven't had time to "fire" it up yet, waiting till the house is empty.)

[mikepukmel]

The Mrs went out to the gym, worked up the nerve to plug it in and ...



It's alive! Put a 60hz test tone through from my computer, measured a little over 15ms (fuzzy trace and all). No sparks, no smoke. No burning bakelite smell. This machine was built when Nixon was president and has not been plugged in since Clinton was president.

Anyone know how to adjust the trace so its not so fuzzy?

[olddawg]

The Mrs went out to the gym, worked up the nerve to plug it in and ...

[ATTACH=CONFIG]48654[/ATTACH]

It's alive! Put a 60hz test tone through from my computer, measured a little over 15ms (fuzzy trace and all). No sparks, no smoke. No burning bakelite smell. This machine was built when Nixon was president and has not been plugged in since Clinton was president.

Anyone know how to adjust the trace so its not so fuzzy?

Most scopes and especially Tek scopes have a calibration lug at 1kh on the front somewhere that you can hang a probe off of. It’s mostly for setting symmetry with different probes but will give you a CLEAN tone. There should also be a “focus” adjustment somewhere. However, given the age of this beast, I suspect that the CRT has simply become gassy. I would set it in the middle of a concrete floor or somewhere where it won’t cause a fire and run it nonstop a few days. Sometimes simply doing that will clear it up a bit. It’s like an old TV.

[mikepukmel]

Thanks Dawg, will do! I looked for a focus adj, didnt see one on the front panel. But I have the manuals thanks to Mick, will pokea round and see what I can find.

[Tom Phillips]

Yes. Try adjusting the focus screwdriver adjustment on the front panel. See info at https://holzleitner.com/el/tektronix-7613/index-en.html and search for other pages about the Tek 7613. There should be lots of information on various web pages and forums.
Tom

[mozz]

Went to a hamfest last week and one seller had about 50 plug-ins, so they are still around.

[nosaj]

Most scopes and especially Tek scopes have a calibration lug at 1kh on the front somewhere that you can hang a probe off of. It’s mostly for setting symmetry with different probes but will give you a CLEAN tone. There should also be a “focus” adjustment somewhere. However, given the age of this beast, I suspect that the CRT has simply become gassy. I would set it in the middle of a concrete floor or somewhere where it won’t cause a fire and run it nonstop a few days. Sometimes simply doing that will clear it up a bit. It’s like an old TV.

Tek 464 has one on the back where the power plugs in . Little bar to clip probe on. Odd it's in the back most I've see are in the front

nosaj

[Enzo]

Yes they are. I have several plug ins for older tube scopes, I will be throwing on ebay soon.

[mikepukmel]

I don't have the skills to rebuild it completely, but I could step through replacing filter caps. The page Tom sent a link to, the guy replaced filter caps to solve some problem.

AFAIK (which isn't much), even if the unit powers up and runs, if the filter caps are weak, i.e. even if they are not shorted or open, it could cause all kinds of strange behavior.

Check out this way cool adapter circuit board: https://www.eevblog.com/forum/testge...37613-repairs/ Looks like he found more or less off the shelf caps, used these boards to do the refurb.