From: "Jim Ford" <james.ford@cox.net>
To: TekScopes@groups.io
Sent: Wednesday, July 22, 2020 11:38:26 PM
Subject: Re: [TekScopes] 485 Cordwrap Feet

Funny you should mention those IEC power connectors, Dennis, as I just
received a new wired router (opting for security, reliability, and speed
for my 3 computers that stay in one place) today, and what do you know,
it did not have an IEC connector on it. Instead, the power cable had a
"3 merged circles" (kind of like 3/5 of the Olympics symbol) connector.
Not sure why.

Funny you should mention those IEC power connectors, Dennis, as I just received a new
wired router (opting for security, reliability, and speed for my 3 computers that
stay in one place) today, and what do you know, it did not have an IEC connector on
it.  Instead, the power cable had a "3 merged circles" (kind of like 3/5 of the
Olympics symbol) connector.
Not sure why.

Hi Jeff,
It was not unusual for the design engineers at Tek to pay attention to
product details (known as Human Factors Engineering in those days) just
like this one. This was one of the things that distinguished Tek from
many other companies. The 485 was a portable scope which meant things
like a power cord had to have a secure place to be while it was being
moved from one place to another. The logical way to carry the scope was
by the handle with the scope in an upright position so there would need
to be feet on the rear of the scope. Why not kill two birds with one
stone and design a foot that would also secure the power cord?

There are some things that the mechanical engineers at Tek never seem
to be satisfied with and cord wraps are one of them. The cord wrap
evolved constantly. It was almost as if the mechanical engineers saw
each new portable scope as an opportunity to improve on the design of
the previous instrument. My 453 (the 454 and 453 were the original
portables Tek designed to meet the needs of the IBM Field Engineers)
had fairly simple rear feet which the power cord could be wrapped
around. I think there was a chance the power cord could become undone
from around the rear feet while travelling with the 453 scope. By the
time the 485 appeared the cord wrap foot was just about optimal: It
holds the power cord securely, and it communicates to the user, by its
unusual shape, what its intended purpose is, without the need for any further explanation.

In other words its unusual shape tells you what it does. Donald Norman
in his book "The Psychology of Everyday Things" coined the term "affordances"
for the properties of objects which show users the actions they can take.
Users should be able to perceive affordances without having to consider
how to use the items. A simple example we all encounter every day is
the handle on a door leading into or out of a store. The shape of the
handle should communicate to you whether you should push or pull it to open the door.
Instead most of them are so poorly designed that it is necessary to
include a sign saying "Push" or "Pull".

With the advent of the IEC power connector standard in 1970 many
instruments gradually started using power cords that could be unplugged
from the instrument which created a totally different problem of what
to do with the proliferation of these power cords now that they are
everywhere. Somehow we all end up with more of them than we can possibly use.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Jeff Davis
Sent: Tuesday, July 21, 2020 12:30 PM
To: TekScopes@groups.io
Subject: [TekScopes] 485 Cordwrap Feet

I had a customer approach me about developing a replacement cord wrap
foot for the Tektronix 485. He sent me one of his that was mostly
intact - but it led to some questions that I'm now posing to the group.

The 485 service manual shows that the cord wrap looks a lot like the
cord wraps on a 2465, i.e. two assemblies, one right side and one left
side, that extend from the bottom to the top, and the cord wraps around
the two of them.

On the other hand, what my customer sent to me looked more like a foot
from a 465, i.e. 4 pieces, one on each corner, with flanges to hold the
cord. The cord wraps around the four pieces located at each corner.

Did early and later versions of the 485 have different cord wraps? If
so, are they interchangeable? I can only find one version of the
service manual, and it shows the 2465-like cord wraps.

Would greatly appreciate anyone who could shed light on this mystery.

Thanks,
Jeff / N0DY
www.n0dy.com





--
Dennis Tillman W7pF
TekScopes Moderator

First modules I'd test out would be the ones that don't use the external
transistors, if there
are any.

How do I know that? The ones I have so far are:
1- PS503A (which was working fine until the 7.5A fuse blew)
2- SC502 15Mhz Scope
3- AM503 Current Probe Amplifier
4- FG502 Function Generator (the one that blew 2 resistors because of the
shorted collectors)
5- DC503 Universal Counter (It has issues, but I don’t think they are power
supply related. But I’m no expert)
6- SG503 Leveled Sine Wave Generator. (That one worked also perfectly)

https://groups.io/g/TekScopes/photo/250733/1?p=Created,,,100,2,0,0

Double check your service manual

For my TM503, the 120V vs 240V selection is done by choosing the jumper of
appropriate color (red or brown as for your TM506).

There is also an extra header to store the unused jumper, just like here (the
top one for your TM506).
And then a set of 3 headers to select the low, middle (230V), and high.

Hi Jeff,
It was not unusual for the design engineers at Tek to pay attention to
product details (known as Human Factors Engineering in those days) just
like this one. This was one of the things that distinguished Tek from
many other companies. The 485 was a portable scope which meant things
like a power cord had to have a secure place to be while it was being
moved from one place to another. The logical way to carry the scope was
by the handle with the scope in an upright position so there would need
to be feet on the rear of the scope. Why not kill two birds with one
stone and design a foot that would also secure the power cord?

There are some things that the mechanical engineers at Tek never seem
to be satisfied with and cord wraps are one of them. The cord wrap
evolved constantly. It was almost as if the mechanical engineers saw
each new portable scope as an opportunity to improve on the design of
the previous instrument. My 453 (the 454 and 453 were the original
portables Tek designed to meet the needs of the IBM Field Engineers)
had fairly simple rear feet which the power cord could be wrapped
around. I think there was a chance the power cord could become undone
from around the rear feet while travelling with the 453 scope. By the
time the 485 appeared the cord wrap foot was just about optimal: It
holds the power cord securely, and it communicates to the user, by its
unusual shape, what its intended purpose is, without the need for any further explanation.

In other words its unusual shape tells you what it does. Donald Norman
in his book "The Psychology of Everyday Things" coined the term "affordances"
for the properties of objects which show users the actions they can take.
Users should be able to perceive affordances without having to consider
how to use the items. A simple example we all encounter every day is
the handle on a door leading into or out of a store. The shape of the
handle should communicate to you whether you should push or pull it to open the door.
Instead most of them are so poorly designed that it is necessary to
include a sign saying "Push" or "Pull".

With the advent of the IEC power connector standard in 1970 many
instruments gradually started using power cords that could be unplugged
from the instrument which created a totally different problem of what
to do with the proliferation of these power cords now that they are
everywhere. Somehow we all end up with more of them than we can possibly use.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Jeff Davis
Sent: Tuesday, July 21, 2020 12:30 PM
To: TekScopes@groups.io
Subject: [TekScopes] 485 Cordwrap Feet

I had a customer approach me about developing a replacement cord wrap
foot for the Tektronix 485. He sent me one of his that was mostly
intact - but it led to some questions that I'm now posing to the group.

The 485 service manual shows that the cord wrap looks a lot like the
cord wraps on a 2465, i.e. two assemblies, one right side and one left
side, that extend from the bottom to the top, and the cord wraps around
the two of them.

On the other hand, what my customer sent to me looked more like a foot
from a 465, i.e. 4 pieces, one on each corner, with flanges to hold the
cord. The cord wraps around the four pieces located at each corner.

Did early and later versions of the 485 have different cord wraps? If
so, are they interchangeable? I can only find one version of the
service manual, and it shows the 2465-like cord wraps.

Would greatly appreciate anyone who could shed light on this mystery.

Thanks,
Jeff / N0DY
www.n0dy.com





--
Dennis Tillman W7pF
TekScopes Moderator

Hi Jeff,
It was not unusual for the design engineers at Tek to pay attention to
product details (known as Human Factors Engineering in those days) just like
this one. This was one of the things that distinguished Tek from many other
companies. The 485 was a portable scope which meant things like a power cord
had to have a secure place to be while it was being moved from one place to
another. The logical way to carry the scope was by the handle with the scope
in an upright position so there would need to be feet on the rear of the
scope. Why not kill two birds with one stone and design a foot that would
also secure the power cord?

There are some things that the mechanical engineers at Tek never seem to be
satisfied with and cord wraps are one of them. The cord wrap evolved
constantly. It was almost as if the mechanical engineers saw each new
portable scope as an opportunity to improve on the design of the previous
instrument. My 453 (the 454 and 453 were the original portables Tek designed
to meet the needs of the IBM Field Engineers) had fairly simple rear feet
which the power cord could be wrapped around. I think there was a chance the
power cord could become undone from around the rear feet while travelling
with the 453 scope. By the time the 485 appeared the cord wrap foot was just
about optimal: It holds the power cord securely, and it communicates to the
user, by its unusual shape, what its intended purpose is, without the need
for any further explanation.

In other words its unusual shape tells you what it does. Donald Norman in
his book "The Psychology of Everyday Things" coined the term "affordances"
for the properties of objects which show users the actions they can take.
Users should be able to perceive affordances without having to consider how
to use the items. A simple example we all encounter every day is the handle
on a door leading into or out of a store. The shape of the handle should
communicate to you whether you should push or pull it to open the door.
Instead most of them are so poorly designed that it is necessary to include
a sign saying "Push" or "Pull".

With the advent of the IEC power connector standard in 1970 many instruments
gradually started using power cords that could be unplugged from the
instrument which created a totally different problem of what to do with the
proliferation of these power cords now that they are everywhere. Somehow we
all end up with more of them than we can possibly use.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff
Davis
Sent: Tuesday, July 21, 2020 12:30 PM
To: TekScopes@groups.io
Subject: [TekScopes] 485 Cordwrap Feet

I had a customer approach me about developing a replacement cord wrap foot
for the Tektronix 485. He sent me one of his that was mostly intact - but it
led to some questions that I'm now posing to the group.

The 485 service manual shows that the cord wrap looks a lot like the cord
wraps on a 2465, i.e. two assemblies, one right side and one left side, that
extend from the bottom to the top, and the cord wraps around the two of
them.

On the other hand, what my customer sent to me looked more like a foot from
a 465, i.e. 4 pieces, one on each corner, with flanges to hold the cord. The
cord wraps around the four pieces located at each corner.

Did early and later versions of the 485 have different cord wraps? If so,
are they interchangeable? I can only find one version of the service manual,
and it shows the 2465-like cord wraps.

Would greatly appreciate anyone who could shed light on this mystery.

Thanks,
Jeff / N0DY
www.n0dy.com





--
Dennis Tillman W7pF
TekScopes Moderator

On Wed, Jul 22, 2020 at 12:23 PM, Harvey White wrote:

You need to look at the manual for the TM506.

3A, 3B, 4A, 4B are all the return for the 11.5 volts.  It's done that
way to share the load on the pins, not an uncommon situation for a design.

That's why the 11.5 volt + leads are paralleled (pin wise), and the 33
volt power supply.

I do that lots, it tends to save pins and wires.  It lowers the
resistance to the other board.

Harvey

So as Ke-Fong Lin said, that’s normal.

I have all the manuals for everything I own. I’m trying to keep up, but I can’t read everything. There are so many subjects. Little by little, I will.