Waking a slumbering 475


Weathers, W
 

Greetings all,

I picked up a Tek 475 with the DM44 option installed. It came with an
HP 10433A 10:1 probe marked "10MOhm // 10pF For 1MOhm // 10-16pF
inputs" (an apparent mismatch for the 475's 20pF input). No scope
manual was included with the sale, unfortunately. I know they can be
downloaded, but I'd like a printed copy. I have been perusing the
electronic copy.

The previous owner said the scope worked when he last used it. It has
been stored in a basement for a number of years. The P.O. had
recently powered it on to verify beam presence and trace on both
channels. I don't think much more has been done to it. And I don't
think it was powered on for very long.

First, a visual condition check:

The case looks to be in good condition. All knobs look to be present,
intact, and operable. The focus knob turns a little hesitantly
compared with the others, but that might be normal. A couple of the
Vertical Mode buttons show deterioration of the silk screen (the Add
and Chop buttons). The Delay Time Position knob is not a metal
graduated vernier knob but instead is an unmarked plastic knob. A
quick search shows similar knobs on some 475s out in the wild, so I
presume this is not the result of a replacement by owner.

The positive jack on the DM44 is loose.

One of the cord-wrap feet has damage to the lower-most cord channel.

There is some scuffing to the display that isn't noticeable when
looking at it head on, but can be seen at an angle. It's almost looks
as if somebody traced a noisy trace onto paper.

The manual/probe pouch smells a bit musty.

Before I do much with this 475, I thought I would check in here so
that I don't inadvertently rudely awaken it and let the smoke out.
How can I best gently wake it up? Are there best prophylactic
practices? I searched here but haven't turned up anything. I am sure
this information exists in the vast body of posts here,but I am having
trouble surfacing it.

This is the first oscilloscope that I have personally owned. I have
used both digital and analog scopes, the vast majority by Tek, though
I have never dug into one.

I am aware that these old scopes have tantalum capacitors that like to
short out. I am also aware that, in general, old electrolytics tend
to be dodgy. Do I need to throw this thing on a variac? And given
that this scope has been a basement queen, I am wondering if something
should be done to address the possibility of long term humidity
effects.

Scopes from the 475 era have a particular personal connection for me,
as my father was a Tektronix veteran. He was a technical writer for
Tek for 20+ years, spanning the 60s and 70s and into the very early
80s. He and his team produced the manuals for oscilloscopes and other
Tek products. If there are any old Tek employees from that era
reading this, yes, my Dad was Stormy.

Ward Weathers

Join TekScopes@groups.io to automatically receive all group messages.