EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: worsthorse on February 19, 2017, 07:40:36 pm
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I spent yesterday morning at the Salem Hamfair. Back in the corner of the the back building, I found a Tek 475A.Dual trace 250Mhz with two clean traces and the basic functions (that I could test) working. Other than being covered with grime and needing a couple of the back feet replaced, it looked pretty good. The ham selling it said he had another one at home and needed to clean out the shack. He asked $125, about $75 less than the two 465s I saw at other tables. I didn't even bargain lest he change his mind.
When I got home, I scanned the forums and found this post, about a 465 restoration...
https://www.eevblog.com/forum/projects/tektronix-465-repair-and-restoration/ (https://www.eevblog.com/forum/projects/tektronix-465-repair-and-restoration/)
...and I thought, boy that was a nice piece of work. and then, I can do that. Going to post before photos here then start tearing it down. I tracked down the service and calibration manuals and will take care of that after going over the internals, cleaning it up, and see whether everything works.
I also picked up a "non-working" Tek CPS250 three output power supply for thirty bucks. Got home changed a couple of blown fuses and now have a much needed lab quality bench power supply. I love ham fleamarkets!
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:-+
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Nice! I love these old Tek scopes, it's great to see people keeping them going.
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Still perfectly useable, especially for linear circuits.
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Pics! :popcorn:
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Very interested to see how it goes. I wouldn't mind tidying mine up a bit.
I fixed a 475 that had quite a number of electronic issues a while back. I did try to remove the panel to do some cleaning etc but found it was really hard to remove nuts off the back of the panel etc. I also ended up damaging one of the fibre glass rods in the process of removing a knob so was shy of going further (I was able to repair it again).
This project was pretty much my first foray into electronics after a very long hiatus. Lots of details, errors and stumbles documented here in case this helps (although it probably won't as yours works).
http://wahz.blogspot.com.au/p/tektronix-475-restoration.html (http://wahz.blogspot.com.au/p/tektronix-475-restoration.html)
Best place to ask about stuff is the Tektronix yahoo group if you get stuck.
Tom
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Still perfectly useable, especially for linear circuits.
Which specifically includes nominally "digital" circuits such as TTL/CMOS/ECL circuits. The only true digital circuits are femtoamp and photon counting applications :)
A 475 is much better than, say a DS1054Z when assuring signal integrity, simply because it has a higher bandwidth.
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i am traveling right now but will post "before" pics when i get back. i have been searching the web for tear down information... the tek scopes are mechanically complex and i am approaching the cleanup gingerly. i don't want it to end up with bent rods or stripped threads! same goes with calibrating, if it needs to be done. i will try to take photos of the tear down, too.
i bought a rigol 1054Z right before i found the 475A. the rigol's advantage is size and features. the tek... bandwidth and familiarity. i will keep both handy, though the reality is i will probably use the rigol more day to day.
i seem to be on a vintage equipment kick. i just picked up a working wavetek 11Mc sweep generator. Between that, the nixie tube frequency counter and the 475A, my bench is starting to look a lot like the one I had in 1980.
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i bought a rigol 1054Z right before i found the 475A. the rigol's advantage is size and features. the tek... bandwidth and familiarity. i will keep both handy, though the reality is i will probably use the rigol more day to day.
It is axiomatic that all scopes lie, so use both of them on the same circuit. That will help you understand how they are lying to you and which bits of information are being "discarded" :)
i seem to be on a vintage equipment kick. i just picked up a working wavetek 11Mc sweep generator. Between that, the nixie tube frequency counter and the 475A, my bench is starting to look a lot like the one I had in 1980.
Be careful; that way lies GAS, TEA, NTSC, PETA and other problematic behaviour.
FFI see https://www.eevblog.com/forum/chat/test-equipment-anonymous-%28tea%29-group-therapy-thread/ (https://www.eevblog.com/forum/chat/test-equipment-anonymous-%28tea%29-group-therapy-thread/)
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Nice! I love these old Tek scopes, it's great to see people keeping them going.
I'm doing my part
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Bought a dead (and smoking) 475A for a steal. :-+
Changed a toasted tantalum and now have a working scope... Albeit in need of calibrating and a general service.
One question.
Is it supposed to have a blue trace? (see photo)
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One question.
Is it supposed to have a blue trace? (see photo)
That was one of the optional phosphors in many of the Tek scopes, it's faster than the more common bluish green. Quite rare as far as I know, I've never actually seen one in the flesh.
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Blue trace is low decay phosphor...Very good for slow events but a little boring for normal use.
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I guess it depends on which specific blue phosphor it is, there are several. I looked it up and here's a list:
http://w140.com/tekwiki/wiki/Phosphor (http://w140.com/tekwiki/wiki/Phosphor)
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I guess it depends on which specific blue phosphor it is, there are several. I looked it up and here's a list:
http://w140.com/tekwiki/wiki/Phosphor (http://w140.com/tekwiki/wiki/Phosphor)
Yes, you are right.....I looked at the technical specifications of the 475 and optional phosphor is P11, not the long decay P7. (standart P31)
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Ok. I see.
The P11 is for photography.
That might explain why there was some camera stuff in the mix with all the cables and accessories.
Thank you very much. :-+