Date   

Re: OT: Homebrew scanning electron microscopes

battyhugh
 

If you are interested (and have room) the Dove auction has a vacuum coating unit (rather needed for SEM). Beautiful piece of gear - if large.
Not sure if the primary vacuum pump is actually bolted down! Second last page.


Dove Auction (USA)

battyhugh
 

http://www.go-dove.com/en/events?cmd=details&event=501802

this seems to be a rather over-supplied auction - loads of 'scopes (Tektronic and others) and power supplies - and enough to set up your own business for a song..


Sphere's Stuff Day coming soon--stay tuned

 

We are trying to balance weather, roads and the best saturday for our annual stuff day event.
Easter long weekend will probably not work, as there's still a lot of snow around, and highways are bad.
so I am guessing mid-april? we are in Kelowna, BC (Canada), not far from Seattle.

anybody interested to come up, or see some advance info on the goodies that will go free and cheap,
please email me off list. There is a ton of HP 8660 RF generator plug in stuff, PMI/Wavetek scalar analyzer gear including sensors, lots of older Tek scopes and literally tons of parts, tools, DMMs, manuals and yes, even two big 19: rack cabinets, FREE if you carry them away in your truck. also all kinds of interesting microwave doo-dads, counters and a few hundred QST/Nuts and Volts back issues, also FREE to promote more reading. We always respond to requests, so if we know you are interested, we can put it out. We have hundreds of CRTs we'd like to see in new homes, and all kinds of RF, industrial, nixie, numitron and audio tubes.

for those unable to make the trip, you might be able to persuade dennis tillman to bring back some gear to washington for you later this month, as we are already going to trade some gear in Vancouver. sort of a check-point charlie kind of thing.

anyway, hope to see some of you for stuff day! it's always a blast.
all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.


FS: Computer and Electronics Magazines

Chris Wilkson
 
Edited

I have many computer and electronics magazines for sale. Some dating back to the 1940's. Fascinating reads. Especially the Radio Electronics stuff.

$1 each. Bulk discounts available. Located in Detroit, Michigan area. Contact me off list.

I uploaded a spreadsheet of what I have available. Creatively named "New Microsoft Excel Worksheet.zip".


Tek 11301 and 11302 Documentation

Kurt Rosenfeld
 

Tek 11301/11302 documentation with schematics is now available.
http://w140.com/tekwiki/wiki/11301


New file uploaded to TekScopes@groups.io

TekScopes@groups.io Notification <TekScopes+notification@...>
 

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the TekScopes@groups.io group.

File: New Microsoft Excel Worksheet.zip

Uploaded By: Chris Wilkson

Description:
Computer and electronics magazines for sale.

You can access this file at the URL:
https://groups.io/g/TekScopes/files/New%20Microsoft%20Excel%20Worksheet.zip

Cheers,
The Groups.io Team


Re: Capacitors Question?

Chuck Harris
 

All SMD aluminum electrolytics are made that way. It keeps
the rubber seal's as far as possible from the oven heat. The
plastic lead forming boots are made from a high temperature
withstanding, thermally insulating plastic material.

They even keep the aluminum cans bare, and mill colored
(white) to take advantage of aluminum's high reflectivity
at IR (heat) wavelengths... they reflect most of the heat
from the oven rather than get hot... Just like you do by
putting aluminum foil strips around a pie crust's edge
to prevent burning...but this only works so well. Keep
the heat on too long, or too hot, and it will cause a
big problem.

What kills most SMD using manufacturers is their desire to
do all of the soldering in the ovens. Even big stuff like
CAT5, USB, DB15's, HDMI, and power connectors.

They get themselves in a bind where if they want the big
stuff to get hot enough to make a good solder joint, they
have to let the little stuff, like SMD electrolytics get
too hot. They get away with it most of the time, but the
parts are damaged, and start to leak during the product's
lifetime.

The proper way to do oven soldering of large parts is to
either do them first, before installing the smaller more
thermally sensitive parts, or do them last, and put an
aluminum heat reflecting cover over the sensitive parts
before you do the oven pass for the big stuff...

But, this amounts to extra hand work, and extra passes
through the oven, and they want things to be cheap.

In my experience, the corrosive electrolyte formulations
do not end up in SMD electrolytic capacitors. Because of
all of the extra steps required to add the plastic cup
and lead forming hardware, it just isn't worth it to
shave a few microcents off by using fake electrolyte.
Even the small size of the aluminum cans puts them out
of reach of the scam artists...

The same is not true of radial leaded electrolytic caps.
They can be built on manufacturing machines that were made
in the 1960's. There is a lot of cheap surplus component
manufacturing equipment out there to enable cheating in
radial leaded capacitor manufacture.

The companies that get fooled are buying parts that are
odd name brands, and much, much cheaper than the usual
name brands. They know, they just don't care.

-Chuck Harris

Dave Casey wrote:
What about the many SMD electrolytics which are just radial electrolytics
anchored in a base with their leads bent over and cut really short?

Dave Casey

On Tue, Mar 6, 2018 at 3:25 PM, Chuck Harris <cfharris@...> wrote:

Not to put too fine a point on my nitpicking, but
AFAIK, the capacitor plague applied only to radial
leaded, low ESR electrolytic capacitors, not to
SMD electrolytic capacitors.
...


Removing 7633 can caps

Brendan
 

I "won" a 7633 from ebay today to use as a parts scope. My current 7633's power supply board is UGLY from my recap. I plan on totally redoing my scope. I want to start with recapping the new power supply and doing a really nice job this time. How do you guys remove those giant can caps? The first one I did I ended up having to cut the tabs and then remove them. Also is it possible to to remove the caps without removing the transformer? I removed it last time and that was part of my issue. I will have a hard time explaining to my wife why I need another 7633 if I mess this up.


Re: TR-501 for $89.99

Craig Sawyers <c.sawyers@...>
 

Nothing on .com or .co.uk with that number.
Ah - it sold in a nanosecond. Almost as good a bargain as my 7L5 for UKP40, my AA501 for USD14 both
on buy it now. Or the new in sealed box 7623B which went the full week with no bids, and I snagged
for USD100, or the 7912HB plus plugins for USD100.

They don't happen often, but it is nice when it happens.

Craig


Re: TR-501 for $89.99

Paul Amaranth
 

It sold around 3:24 EST. I had to look in the sold listings to find it.

Paul

On Wed, Mar 07, 2018 at 08:56:42PM -0000, Craig Sawyers wrote:
Nothing on .com or .co.uk with that number.

Craug

Subject: [TekScopes] TR-501 for $89.99
"Buy It Now" 382402728832



Rolynn





!DSPAM:5aa04e7a183572923344938!
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows


Re: TR-501 for $89.99

Craig Sawyers <c.sawyers@...>
 

Nothing on .com or .co.uk with that number.

Craug

Subject: [TekScopes] TR-501 for $89.99
"Buy It Now" 382402728832



Rolynn


TR-501 for $89.99

ROLYNN PRECHTL K7DFW
 

"Buy It Now" 382402728832



Rolynn


Re: AWG2040 Strange Connector?

Harvey White
 

On Wed, 07 Mar 2018 09:19:58 -0800, you wrote:

All:

I have recently acquired a TEKTRONIX AWG2040 with a strange connector on the side, where the disk drive would normally reside. I opened the case and this appears to be a factory installed item, but I cannot find reference to this in the service manual. Maybe I am overlooking this. It almost looks like a Mini-Centronix, except it uses screw retainers instead of spring loaded hook retainers. I am guessing this is an output for an external drive, since this was probably rack mounted and a floppy drive would not have been accessible. but I do not know what type of drive to connect. Anyone have any feedback about this?
Guessing: IEEE-488?

Harvey


Link to GOOGLE Drive Photo

https://drive.google.com/file/d/0Bz6RdWEJXyUDc1UzOVI0QjkwbXgxT1BDa2dGS1ZxV0dmVWYw/view?usp=sharing



Re: Capacitors Question?

Michael A. Terrell
 

You've never seen a modern reflow oven in operation. It doesn't 'bake' boards. There is a very minimum of three stages: preheat stage, the reflow stage and the cooling stage. The Heller oven we used at Microdyne had over a dozen stages, and a profile for each board that we produced was stored in the computer that controlled it. The reflow stage was as short as possible, to prevent any damage, but long enough to ensure proper reflow. Otherwise, plastic cased components like relays and trimpots would melt. Here is a link to one of the Heller ovens of that time period:

<http://islandsmt.com/wp-content/uploads/2017/02/1707EXL-Heller-Manual-680441-ver3.8.pdf>

As far as gluing components, the boards we built never used any glue. The surface tension of the paste solder held the components in place. They were double sided, and 16 layer VME based boards were common.

-----Original Message-----
From: M Yachad <@yachadm>
Sent: Mar 7, 2018 12:36 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Capacitors Question?

A large part of my business is TV repair. The modern LCD TV motherboards are just as unreliable as the older 80's - 90's first generation SMD motherboards.
It is the norm that I have to replace ALL the SMD electrolytics on a 2-year-old LCD TV, to get it back to working condition (Other service centers tell the customer "You need a new board").

This high failure rate is due to mainly ONE cause - the SMD baking process.
All SMD components are glued onto the PCB, and then baked in an oven at about 300C to flow the solder onto the joints.
Just imagine what that does to the electrolyte inside the caps.

Maybe Vishay, Nichicon and Panasonic caps are built to withstand that heat and pressure during baking, but when was the last time you saw any of those quality caps inside a consumer-grade TV?

So, as long as baking PCB's is an integral part of production, the problem of short lifetimes of SMD electrolytics is NOT going to go away any time soon.



Michael A. Terrell


Re: Tek 547 A Sweep display during retrace

Christopher Hilton-Johnson
 

David

glad to have been of help

At least there now seem to be adequate choices for solving the 'where have all the 2n2207's gone'

so thank you for your time and success in sorting out this issue

Christopher

On 05/03/2018 18:33, Dave Wise wrote:
Thank you, Chris, for your kind gift of a Siemens AF118 transistor for testing.

At least in the Q373 position*, your sample AF118 performed like a 2N2207.  I saw 60ns delay and 25ns rise vs 50ns/35ns for 2N2207, giving the same turn-on time.

That said, my recommendation stands: BC556 or KSA992, with 220pF added to the speedup cap.  That's cheap and abundant and anyone can do it, not just the oddball with a box of AF118's.  :)

Thanks,
David

* Should be the same in the Q173 position but I didn't test it.
________________________________________
From: TekScopes@... on behalf of Christopher Hilton-Johnson chj@... [TekScopes] <TekScopes@...>
Sent: Saturday, November 25, 2017 2:15 AM
To: TekScopes@...
Subject: Re: [TekScopes] Re: Tek 547 A Sweep display during retrace

Have you looked at the AF118 as a replacement for the 2N2207?

I ask, because most of my pulls were AFs pretending to be 2Ns

Chris HJ​


Re: Storage CRT Modes Question

bobh@joba.com
 

And another great Tek pub talking 7834 storage as well as other topics often discussed here.

http://w140.com/tekwiki/images/4/4f/Tekscope_1977_V9_N1.pdf

Bob.

On 3/7/2018 8:12 AM, unclebanjoman wrote:
Take a look at this:

http://w140.com/tekwiki/images/f/f9/Tekscope_1972_V4_N4_Jul_1972.pdf



AWG2040 Strange Connector?

Mlynch001
 
Edited

All:

I have recently acquired a TEKTRONIX AWG2040 with a strange connector on the side, where the disk drive would normally reside. I opened the case and this appears to be a factory installed item, but I cannot find reference to this in the service manual. Maybe I am overlooking this. It almost looks like a Mini-Centronix, except it uses screw retainers instead of spring loaded hook retainers. I am guessing this is an output for an external drive, since this was probably rack mounted and a floppy drive would not have been accessible. but I do not know what type of drive to connect. Anyone have any feedback about this?

Link to GOOGLE Drive Photo

https://drive.google.com/file/d/0Bz6RdWEJXyUDc1UzOVI0QjkwbXgxT1BDa2dGS1ZxV0dmVWYw/view?usp=sharing

Thanks In advance,

Michael Lynch


Re: Tek 7623A - Inverted and compressed Horizontal only from TB (was 7623A + 7A26 + 7B53)

kc0wox Leeper
 

Here's a link to troubleshooting a 7504 horizontal amp. It may have some sections that are similar to yours. It starts with a power supply problem and has a link to the horizontal amp.

http://golddredgervideo.com/kc0wox/tek/7504/

Leonard


Re: Diode 5082-2068 Substitute or Source

 

I accidently send an early draft. I am still working on this one.

On Wed, 07 Mar 2018 09:22:13 -0600, you wrote:




Forward voltage matching is not important in this application because
the bridge is switching currents.

Haven't we discussed the HP 5082-2068 diode here in the past? I could
not find that diode in any of the HP databooks making me wonder if the
HP part number given by Tektronix is wrong but the Tektronix data is
just as good for this - 25V 100nA 2.0pF - although the specifications
do not match any HP diodes.

HP does not really specify maximum current but instead specifies the
current at 1 volt which for the 5082-2800, which is the same as a
1N5711, 15 milliamps which is on the low side. Their 20 and 30 volt
diodes are mostly 35 millamps with some at 50 and 75 milliamps. These
parts are equivalent to the 1N5165, 1N5166, and 1N5167.

I wonder if schottky diodes were strictly required. I suspect 1N916,
1N4448, or 1N4152 switching diodes which are 2pF should work almost as
well. The 1N5711, BAT41, BAT81, BAT82, and BAT83 are all common low
capacitance schottky diodes which should work. The BAT41 has the
lowest leakage but the BAT81/2/3 has the lowest capacitance.

Something clever which could be done is to use two diodes in series
for each original diode to knock the capacitance down by half.

On Sun, 04 Mar 2018 19:53:05 -0800, you wrote:

It was a typo, I meant FG502

CR140 152-0457-00 SEMICOND DEVICE :SILICON,25V 28480 5082-2068
CR145 152-0457-00 SEMICOND DEVICE :SILICON,25V 28480 5082-2068
CR170 152-0457-00 SEMICOND DEVICE :SILICON,25V 28480 5082-2068
CR175 152-0457-00 SEMICOND DEVICE :SILICON,25V 28480 5082-2068

These are in a bridge as a current switch in the triangle wave generator. In troubleshooting
I found that one was open. I pulled a hot carrier diode out of a junker 7B80. It was only rated
at 20V, used it to test the fix, it never even sees even 20V. Only works partially!. In reading about
these diodes, it stated they have some maximum limiting current, where the resistance goes up
If so, I am seeing that, it does not conduct well enough. I got 5 diodes on the way, 30v 200ma
switching diodes. So I was interested in a spec sheet to see what the rated current is on the
5082-2800 diode.

Thanks for the responses, Stan


Re: Diode 5082-2068 Substitute or Source

 

Forward voltage matching is not important in this application because
the bridge is switching currents.

Haven't we discussed the HP 5082-2068 diode here in the past? I could
not find that diode in any of the HP databooks making me wonder if the
HP part number given by Tektronix is wrong but the Tektronix data is
just as good for this - 25V 100nA 2.0pF - although the specifications
do not match any HP diodes.

HP does not really specify maximum current but instead specifies the
current at 1 volt which for the 5082-2800, which is the same as a
1N5711, 15 milliamps which is on the low side. Their 20 and 30 volt
diodes are mostly 35 millamps with some at 50 and 75 milliamps. These
parts are equivalent to the 1N5165, 1N5166, and 1N5167.

I wonder if schottky diodes were strictly required. I suspect 1N916,
1N4448, or 1N4152 switching diodes which are 2pF should work almost as
well. The 1N5711, BAT41, BAT81, BAT82, and BAT83 are all common low
capacitance schottky diodes which should work. The BAT41 has the
lowest leakage but the BAT81/2/3 has the lowest capacitance.

Something clever which could be done is to use two diodes in series
for each original diode to knock the capacitance down by half.

On Sun, 04 Mar 2018 19:53:05 -0800, you wrote:

It was a typo, I meant FG502

CR140 152-0457-00 SEMICOND DEVICE :SILICON,25V 28480 5082-2068
CR145 152-0457-00 SEMICOND DEVICE :SILICON,25V 28480 5082-2068
CR170 152-0457-00 SEMICOND DEVICE :SILICON,25V 28480 5082-2068
CR175 152-0457-00 SEMICOND DEVICE :SILICON,25V 28480 5082-2068

These are in a bridge as a current switch in the triangle wave generator. In troubleshooting
I found that one was open. I pulled a hot carrier diode out of a junker 7B80. It was only rated
at 20V, used it to test the fix, it never even sees even 20V. Only works partially!. In reading about
these diodes, it stated they have some maximum limiting current, where the resistance goes up
If so, I am seeing that, it does not conduct well enough. I got 5 diodes on the way, 30v 200ma
switching diodes. So I was interested in a spec sheet to see what the rated current is on the
5082-2800 diode.

Thanks for the responses, Stan