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I decided I would replace the electrolytic on the regulator board as I noticed the capacitors appear quite old.

On removing the board and looking at some of the radial style capacitors I noticed they are not your standard capacitors. The bigger capacitors have 4 metal feet towards the rim that seem to serve two purposes, hold the capacitor in place and serve as a electrical connection. And then there is a a 5th connector towards the middle.

I am thinking if I replace these I will need to come up with some kind of retrofit unless they stock similar capacitors like these.

And thoughts? Thanks

I haven't opened up a 577, but those are likely the typical Sprague capacitors
used by Tektronix in that era. They may still be good; I'd check them with a
good capacitor and esr meter before removing them.

If you need to replace them, the neatest repair is one I use in 4xx and 7K scopes - use
a small carrier board to mate the footprint to a commonly available snapcap. This
provides the jumpers that Tek used and the footprint for the new cap. Use
105C caps as replacements. You can find these on ebay and there are gerbers floating
around if you want to send them to a board house yourself. You can also etch them
yourself of course.

Some purists might restuff the cans with a new snapcap.

Paul

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix & Windows

Thanks, and if I understand right +75-10? is 75C tempature and 10% tolerance.

Any idea what the manual is referring to when it is describing a capacitor under the parts list by CER DIR, seems like the CER might be ceramic but DI I am not sure

On Fri, Aug 9, 2019 at 10:27 AM, DW wrote:

Thanks, and if I understand right +75-10? is 75C tempature and 10% tolerance.

Any idea what the manual is referring to when it is describing a capacitor
under the parts list by CER DIR, seems like the CER might be ceramic but DI I
am not sure

In my experience, that rating is +75% -10% (capacitance) and most Tektronix caps are rated at 85C or occasionally better.
--
Michael Lynch
Dardanelle, AR

On Fri, Aug 9, 2019 at 10:27 AM, DW wrote:

Any idea what the manual is referring to when it is describing a capacitor
under the parts list by CER DIR, seems like the CER might be ceramic but DI I
am not sure

I do not have a 577 in front of me, But I am thinking that "CIR DI" stands for "Ceramic Disc".
--
Michael Lynch
Dardanelle, AR

That is correct.? A rating of -10%/+75% is indeed a capacitance tolerance specification.? For a while they used GMV as a tolerance, meaning Guaranteed Minimum Value.? When bypassing, tolerance isn't very important.? But price is.? The wider the tolerance, the fewer rejects and the easier testing becomes.
Bob

This might work

On Fri, Aug 9, 2019 at 09:25 AM, Paul Amaranth wrote:

I haven't opened up a 577, but those are likely the typical Sprague capacitors
used by Tektronix in that era. They may still be good; I'd check them with a
good capacitor and esr meter before removing them.

If you need to replace them, the neatest repair is one I use in 4xx and 7K
scopes - use
a small carrier board to mate the footprint to a commonly available snapcap.
This
provides the jumpers that Tek used and the footprint for the new cap. Use
105C caps as replacements. You can find these on ebay and there are gerbers
floating
around if you want to send them to a board house yourself. You can also etch
them
yourself of course.

Some purists might restuff the cans with a new snapcap.

Paul

Paul,

I have become quite adept at re-stuffing cans with modern capacitors. I "restuffed" all the filter caps in my TYPE 576 power supply with modern caps. Having previously just replaced these large cans with modern caps, there is something about the "look" of those large cans that is satisfying, in a way that small and modern caps just cannot replicate. With me, it is not so much being a purist, just about scale, symmetry and general appearance that drives me to do this. I appreciate your insight and advice regarding this problem.


--
Michael Lynch
Dardanelle, AR

Thanks for all the helpful replies!

I recently post a link,


These adapter boards accept through hole lead designed capacitors. A particular capacitor I was looking at on the regulator board of the 577 is a 1700uF 250V capacitor. I found a 1800uF capacitor but it has the snap on terminals which I don't think will fit on these adapter boards, would anyone know of a lead type capacitor around 1700uF 250V? Perhaps I could modify the terminals of the snap on capacitor so it could fit. Thanks

When in doubt just ask the seller selling the adapter board, they will see if they can make a version of this board that accepts snap on capacitors

We have several sizes of boards that take snap-in caps and replace the old “twist tab” and screw-in caps

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
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Thanks, here is some more details

Tektronix 577 power supply C744 1700uF 250V, the capacitor has a 4 point triangle mount on the board

Here is a capacitor I am trying to fit


And here is a picture of the board and detailed caption below the picture
/g/TekScopes/photo/86536/0?p=Created,,,20,2,0,0