Date   

Re: TDS794D with broken Hard drive

Holger Lübben
 

Hi!

3D printing is mostly correct...

I've documented the conversation here:

http://w140.com/tekwiki/wiki/TDS420

My TDS420A was equipped with a normal sized floppy drive including an L-shaped plastic adapter on one side. So the Gotek drive could be installed without any additional work.
My new scope didn't have this adapter. So I made a little corner piece to fill the gap.


Re: 485 Cordwrap Feet

Jeff Davis
 

@Barry, @Chuck, @Dennis, @Dave, @Jim, @Roy, @Michael W. Lynch via groups.io<mailto:mlynch003=yahoo.com@groups.io>

Thanks for your responses. At the risk of returning the thread to the original topic 🙂, I thought I'd clear the mystery up, at least a little bit.

Turns out the customer DOES have a 485. But clearly, his 485 does NOT have the original cord wrap. It appears that at some time in the past, they were replaced with the feet that I shared in the photo album. If you'll look, you'll see that there's a notch cut out of one side of the foot. That apparently was done to make the foot fit onto the scope and avoid interference with the housing protrusion. I added a photo of the foot installed to the album https://groups.io/g/TekScopes/album?id=250966.

So, mystery partially solved. I have some idle curiosity about where the foot came from as it's clearly not a 454, 465, or 475 foot (I know those by sight). But I can live with it. One day I'll come across one and the light bulb may (or may not) light up.

Jeff

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of n4buq <n4buq@knology.net>
Sent: Thursday, July 23, 2020 6:07 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] 485 Cordwrap Feet

I think I've heard those referred to as "Mickey Mouse" connectors.

Thanks,
Barry - N4BUQ

----- Original Message -----
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.


Re: TM506

Michael W. Lynch
 

On Thu, Jul 23, 2020 at 04:10 AM, Colin Herbert wrote:


I think you have maybe made an error in your description of the "PS503A does
not use the pass transistors". Tek were a bit naughty in not putting blue
boxes around them on the schematic in the Service Manual. When you think about
it logically, since the PS503A can supply up to 1.0 A in a high-power bay and
is limited to 400 mA in a standard bay, it stands to reason that it _must_ be
using the pass transistors. Perhaps you simply got the plug-in ID wrong (a
typo).
Colin,

Unfortunately, I forgot about the "logic" part and and simply forged ahead, trusting that TEK would indicate the Pass transistors with the outlined Blue Box in the schematic like so many others. I "assumed" that since there was no such indication in the schematic that the plugin did not utilize the mainframe Pass Transistors. Just a boneheaded error and case of speaking before thinking logically. I learned something new from that mistake.

Thanks!

--
Michael Lynch
Dardanelle, AR


Re: TDS794D with broken Hard drive

Martin Hodge
 

On Thu, Jul 23, 2020 at 06:56 AM, Holger Lübben wrote:


Based on the suggestion I picked up a CF card with an CF to IDE adapter.
For the first tests I took the cheapest card and adapter I could get. And they
work perfectly.
The adapter has to be configured as "Master" and the card has to be formatted
as FAT16. This limits the maximum capacity to somewhere around 4GB.
I've added a picture of the result to the photo album of this group.

The next step is to get one of those adapters in the formfactor of a 2.5" hdd
and maybe a more professional card. This will the modification more easily.

I'll post the progress here and on tekwiki.

Holger

I'm interested in that Gotek adapter you have installed. Is there a specific model to look for or did you 3d print it?


Re: 485 Cordwrap Feet

n4buq
 

I think I've heard those referred to as "Mickey Mouse" connectors.

Thanks,
Barry - N4BUQ

----- Original Message -----
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.


Re: 485 Cordwrap Feet

Chuck Harris <cfharris@...>
 

That is an IEC connector.... just not the type
you are used to.

It is known as a Mickey Mouse connector because of
the profile.

-Chuck Harris

Jim Ford wrote:

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.


Re: TDS794D with broken Hard drive

Holger Lübben
 

Based on the suggestion I picked up a CF card with an CF to IDE adapter.
For the first tests I took the cheapest card and adapter I could get. And they work perfectly.
The adapter has to be configured as "Master" and the card has to be formatted as FAT16. This limits the maximum capacity to somewhere around 4GB.
I've added a picture of the result to the photo album of this group.

The next step is to get one of those adapters in the formfactor of a 2.5" hdd and maybe a more professional card. This will the modification more easily.

I'll post the progress here and on tekwiki.

Holger


Re: 485 Cordwrap Feet

Dave Brown
 

More commonly known as the cloverleaf power connector.......
DaveB, NZ

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Dennis Tillman W7pF
Sent: Thursday, July 23, 2020 16:56
To: TekScopes@groups.io
Subject: Re: [TekScopes] 485 Cordwrap Feet

Hi Jim,
That is the official IEC connector recommended for switching mode power supplies. See examples of other official IEC 60320 shapes (there are at least 15 different ones) each specified for a different purpose.
https://en.wikipedia.org/wiki/IEC_60320
Dennis Tillman W7pF


-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jim Ford
Sent: Wednesday, July 22, 2020 9:38 PM
To: TekScopes@groups.io
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.

Now, my Tek 5103N/D10 and 7603 scopes have attached power cables, and every other piece of gear (most of it Tek or HP) I own except for the HP 400E AC voltmeter (pre-1970, no doubt) has a detachable cord with an IEC connector on it. No, wait, that's not true. I noticed some time ago that the 3 power supplies I own, an HP 6111A, an Elenco Precision XP-581, and a Trygon TL8-3, all have attached cords. I wonder why that is...

Another oddball is my Tek TLA711 mainframe. While it has an IEC male connector on the back of it, there is an extra rib below the GND pin, so a normal IEC female will not mate with it. Until you chop a groove into it with a utility knife, that is. I don't know why Tek did that. Maybe if you fill up the chassis with a thousand channels worth of logic analysis it draws so much current you need an extra beefy power cable (with a special notched IEC connector) hooked up to a 100 A circuit?

Speaking of extra beefy power cords, I have one I got from Mercury Transformers at the L.A. Guitar Amp Show some years ago. They were giving away these slick, fat, red cables. I'm not going to hook that up to just anything; no, that one is being saved for something special!
Seems like I have dozens of normal ones, though. The ones with the right angle IEC connectors come in handy when using a deep piece of equipment like a 7904 up close to the wall. But they always seem to point the wrong way, as do GPIB connectors. ;)

Rambling again - sorry.

Jim Ford

------ Original Message ------
From: "Dennis Tillman W7pF" <dennis@ridesoft.com>
To: TekScopes@groups.io
Sent: 7/22/2020 11:39:48 AM
Subject: Re: [TekScopes] 485 Cordwrap Feet

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







--
Dennis Tillman W7pF
TekScopes Moderator


Re: TM506

Colin Herbert
 

I think you have maybe made an error in your description of the "PS503A does not use the pass transistors". Tek were a bit naughty in not putting blue boxes around them on the schematic in the Service Manual. When you think about it logically, since the PS503A can supply up to 1.0 A in a high-power bay and is limited to 400 mA in a standard bay, it stands to reason that it _must_ be using the pass transistors. Perhaps you simply got the plug-in ID wrong (a typo).

I have looked at my TM504, which has a high-power bay and checked the high-power pass transistors. They are RCA 051 0140 and RCA MJ 2955 (at least that is what some of the writing shows). They are mounted on the back of the mainframe and have black plastic covers to prevent shorts to anywhere. Incidentally, they are a right !!! to re-fasten once you remove the screw securing the plastic cover. That screw also fastens the transistor and has a nut, a metal washer and a plastic insulating washer. Getting all of those back on properly is a right royal pain, as the access space is limited. I still haven't completed that job, but I only did the investigation last night before dinner. Today's important job.....
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Michael W. Lynch via groups.io
Sent: 22 July 2020 22:54
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM506

On Wed, Jul 22, 2020 at 03:03 PM, Stephen wrote:



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)
Check the Schematics and Circuit descriptions for these various modules. The schematics will show the Pass transistor enclosed in a block or dotted line and usually states near the device "located in Mainframe".

PS503A does not use the pass transistors
SG503 Does use both of the pass transistors and this module can be a very problematic one.
DC503 Does use both pass transistors.
FG502 Does use both pass transistors.

Good Luck.,
--
Michael Lynch
Dardanelle, AR


Re: TM506

 

All are available from electronics suppliers, just not off the shelf in your normal shop.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Stephen
Sent: 23 July 2020 09:29
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM506

On Wed, Jul 22, 2020 at 09:10 PM, Ke-Fong Lin wrote:


https://groups.io/g/TekScopes/photo/250733/1?p=Created,,,100,2,0,0
Double check your service manual
.
I have.

For my TM503, the 120V vs 240V selection is done by choosing the jumper of
appropriate color (red or brown as for your TM506).
The Brown is apparently stored. And the red is in the middle position.

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.
It is in the middle position at the moment.
I’m off to get some 1.5A or 2A Fast fuses for the DC503A. I’m not sure if 1.5A is a normalized value and available though.


Re: TM506

Stephen
 

On Wed, Jul 22, 2020 at 09:10 PM, Ke-Fong Lin wrote:


https://groups.io/g/TekScopes/photo/250733/1?p=Created,,,100,2,0,0
Double check your service manual
.
I have.

For my TM503, the 120V vs 240V selection is done by choosing the jumper of
appropriate color (red or brown as for your TM506).
The Brown is apparently stored. And the red is in the middle position.

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.
It is in the middle position at the moment.
I’m off to get some 1.5A or 2A Fast fuses for the DC503A. I’m not sure if 1.5A is a normalized value and available though.


Re: TM506

Ke-Fong Lin
 

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.


Re: Looking for TDS6804B pictures or TDS6/7000B series acquisition boards, bad or good

guy_ellis_1964
 

Hi Flyte,

I've got a TDS6604 here that I'm working on - I'd be interested to know the differences in the Acq. boards.
Mine has a trigger problem and SPC fail.
Maybe we can share notes?

Regards,
- Guy.


Re: Triggering problem with TDS6604

guy_ellis_1964
 

Hi Jim,

Did you ever solve the trigger problem with your TDS6604, as I got one here with the same symptom?

All of the diagnostic tests pass except SPC.

This unit had a flat NOVRAM battery - not sure if that is related.

Regards,
- Guy.


Re: TM506

Stephen
 

On Wed, Jul 22, 2020 at 01:32 PM, Dennis Tillman W7pF wrote:


Be sure the input voltage selector jumpers inside the TM506 are set to the
proper voltage range your electric utility provides. If they do not match your
power line voltage the three AC voltages and the three DC voltages of the
TM506 will be ~15% higher or lower than they should be.

Dennis Tillman W7pF
Yes Dennis, I get that.
But this is what I have inside the unit, and nowhere is it specified, inside the unit or in the manual, what does what....
My line voltage is >= to 230VAC (Close to 235VAC). Apparently this unit is set for 220V.
I don’t want to change anything until I’m sure I’m doing the right thing.

This is how it’s set at the moment:
https://groups.io/g/TekScopes/photo/250733/0?p=Created,,,100,2,0,0
https://groups.io/g/TekScopes/photo/250733/2?p=Created,,,100,2,0,0
https://groups.io/g/TekScopes/photo/250733/1?p=Created,,,100,2,0,0


Re: 11A16 Problem

Steve C
 

This may be, but there is no flashing of the CH1 or CH2 LEDs. I don't have any fault code from the plug-in, just what I see on the DSA602 screen: "Comm Test in Progress" and then "Illegal self test cmd". This may be one of the initial steps the communication is set up, before any self test starts.

Thanks,
Steve


Re: 11A16 Problem

Egge Siert
 

Hi Steve,

I never experienced such a problem with the 11000 Series (and yes I have a 11A16). It looks to me as a problem with the Kernel Tests. See page 3-2 of the Service Manual.

Greetings,

Egge Siert


Re: 485 Cordwrap Feet

 

Hi Jim,
That is the official IEC connector recommended for switching mode power supplies. See examples of other official IEC 60320 shapes (there are at least 15 different ones) each specified for a different purpose.
https://en.wikipedia.org/wiki/IEC_60320
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jim Ford
Sent: Wednesday, July 22, 2020 9:38 PM
To: TekScopes@groups.io
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.

Now, my Tek 5103N/D10 and 7603 scopes have attached power cables, and every other piece of gear (most of it Tek or HP) I own except for the HP 400E AC voltmeter (pre-1970, no doubt) has a detachable cord with an IEC connector on it. No, wait, that's not true. I noticed some time ago that the 3 power supplies I own, an HP 6111A, an Elenco Precision XP-581, and a Trygon TL8-3, all have attached cords. I wonder why that is...

Another oddball is my Tek TLA711 mainframe. While it has an IEC male connector on the back of it, there is an extra rib below the GND pin, so a normal IEC female will not mate with it. Until you chop a groove into it with a utility knife, that is. I don't know why Tek did that. Maybe if you fill up the chassis with a thousand channels worth of logic analysis it draws so much current you need an extra beefy power cable (with a special notched IEC connector) hooked up to a 100 A circuit?

Speaking of extra beefy power cords, I have one I got from Mercury Transformers at the L.A. Guitar Amp Show some years ago. They were giving away these slick, fat, red cables. I'm not going to hook that up to just anything; no, that one is being saved for something special!
Seems like I have dozens of normal ones, though. The ones with the right angle IEC connectors come in handy when using a deep piece of equipment like a 7904 up close to the wall. But they always seem to point the wrong way, as do GPIB connectors. ;)

Rambling again - sorry.

Jim Ford

------ Original Message ------
From: "Dennis Tillman W7pF" <dennis@ridesoft.com>
To: TekScopes@groups.io
Sent: 7/22/2020 11:39:48 AM
Subject: Re: [TekScopes] 485 Cordwrap Feet

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







--
Dennis Tillman W7pF
TekScopes Moderator


Re: 485 Cordwrap Feet

Jim Ford
 

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.

Now, my Tek 5103N/D10 and 7603 scopes have attached power cables, and every other piece of gear (most of it Tek or HP) I own except for the HP 400E AC voltmeter (pre-1970, no doubt) has a detachable cord with an IEC connector on it. No, wait, that's not true. I noticed some time ago that the 3 power supplies I own, an HP 6111A, an Elenco Precision XP-581, and a Trygon TL8-3, all have attached cords. I wonder why that is...

Another oddball is my Tek TLA711 mainframe. While it has an IEC male connector on the back of it, there is an extra rib below the GND pin, so a normal IEC female will not mate with it. Until you chop a groove into it with a utility knife, that is. I don't know why Tek did that. Maybe if you fill up the chassis with a thousand channels worth of logic analysis it draws so much current you need an extra beefy power cable (with a special notched IEC connector) hooked up to a 100 A circuit?

Speaking of extra beefy power cords, I have one I got from Mercury Transformers at the L.A. Guitar Amp Show some years ago. They were giving away these slick, fat, red cables. I'm not going to hook that up to just anything; no, that one is being saved for something special!
Seems like I have dozens of normal ones, though. The ones with the right angle IEC connectors come in handy when using a deep piece of equipment like a 7904 up close to the wall. But they always seem to point the wrong way, as do GPIB connectors. ;)

Rambling again - sorry.

Jim Ford

------ Original Message ------
From: "Dennis Tillman W7pF" <dennis@ridesoft.com>
To: TekScopes@groups.io
Sent: 7/22/2020 11:39:48 AM
Subject: Re: [TekScopes] 485 Cordwrap Feet

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



Re: TM506

Harvey White
 

Not a problem.  Been doing something like this for a while, so I know where some bodies are buried.  If you haven't, then you're still learning that part of it.  Connector pins have a maximum rated current, so paralleling them can be a good design feature. You can see that in some designs.

Harvey

On 7/22/2020 7:34 PM, Stephen wrote:

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.


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