Re: 547 scope HV transformer problem. One practical solution.


I once ran into a former Tek employee at a hamfest where I was looking over
one of the 500-series scopes. He said that in the day when Tek serviced
them, they washed them with water and then warm-air dried them. I will have
to look for that publication to verify what he said. I don’t doubt it would
work with the tube-type scopes but I’d have some concerns about doing that
with the solid state ones. Some of the switches in the plug-ins don’t look
waterproof but also look like they would be difficult to dry out with air.

I’m new to this group, but not to using Tek scopes. My first was a purchase
from DoD Surplus Sales (back before they privatized it). It was a 545A and
was DOA. I found the problem quickly - a bad resistor in the power supply.
I replaced that, and the scope powered right up. I had several of the
500-series after that (a 585, 547, and a 556 - should have kept that one. I
donated the scopes to the lab I was working in when I left. By that time, I
started getting the 7000-series scopes and still have most of those (a
7704A, 7904A, 7104, R7844, 7854). I also had an oddball 7000-series that I
think was a short-lived precursor of the 7854. It had a section in between
the plug-ins and the display that, like the 7854, had a number of waveform
computing functions. I don’t recall the number and I no longer have it - I
sold it at a hamfest. Also, I don’t see it on TekWiki. I still use the
R7844 on occasion, but have mostly turned to the TDS3054C digital. I know
the analog folks have likely instantly put me on their “oust from the
group” list, but it’s a matter of practicality - portability and I’m not
worried about aliasing for the applications I have. I have found the Tek
scopes over the years to be reliable and with all the plug-ins, very


On Sat, Feb 22, 2020 at 15:35 Randy Newman <>

Hi Ernesto.
As a happy 555 owner (beautiful sharp blue trace (p13 phosphor?). Re
washing, check the BAMA (Boat Anchor ....) and look in the tek section for
tektronix magazines....or maybe I am thinking of the site.
Yes...the latter...see the 111wiki, then section 38 manuals, catalogs, and
other publications...then "Tektronix magazines" Tekscope vol 8 no. 4
1976..has tek's scope washing procedure. This is a 2-parter..don't have the
other issue...might be vol 9 no. 1. Plus there is a wealth of information
on tube and xsistor scopes. I also have a 7834, 7633, and 7623. But I
really like the 555, even with its external supply(!!). Nice garage
heater....some day I will have a real shop area.
Hope this helps!

On Thu, Feb 20, 2020, 9:27 AM Ernesto <ebordon@...> wrote:

Hi John, thank you for pointing me to the world of oscilloscope washing,

I read about the experiences of others and the industry washing
oscilloscopes with water. The hairs on my head used to stand up at the
idea, but now I recognize that it is relatively safe, although it
requires WORK.
I compare it with my long experience of "don't fix what is not broken",
and the good luck I have with my old scope that had a 40 years leave of

I perfectly cleaned the exterior of my 547, and it is shiny. The inside
is different, with plenty of dust deposited on the tubes and surfaces.
like to preserve it like that for its dramatic effect. The instrument
be perfect for my grandchildren to play with it when they are a little
bigger, and it may awaken their interest in electronics. I plan to show
them the inside of the scope to be impressed with its age, but after
the inside will be off limits to them.

But... if I experience any failures, I feel competent enough to trace
them to the failed component, or particles of dust, and I will remove
just those offending particles.

NOTE: I have a different standard for washing myself, staying clean
and changing my underwear, ha ha ha.


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