Date   

Re: Obfusctated email adresses in archive

n4buq
 

I get almost the same thing except the address is mingled with groups.io. I can usually figure it out but it isn't exactly as clear in my email reader as your example.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Colin Herbert via groups.io" <colingherbert=blueyonder.co.uk@groups.io>
To: TekScopes@groups.io
Sent: Monday, June 22, 2020 10:12:09 AM
Subject: Re: [TekScopes] Obfusctated email adresses in archive

Oddly enough, I get to see email addresses. At the top of emails is something
like:

"TekScopes@groups.io; on behalf of; Harry Houdini
<harryhoudini@magicianmail.com>"

I don't understand why, but there you go. I didn't do anything special to get
this, perhaps it's because I am in the UK?

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David
DiGiacomo
Sent: 22 June 2020 15:08
To: TekScopes
Subject: Re: [TekScopes] Obfusctated email adresses in archive

On Mon, Jun 22, 2020 at 6:53 AM David C. Partridge
<david.partridge@perdrix.co.uk> wrote:

Dennis,

It's possible to change the group settings to not hide email addresses in
the archive. If anyone is concerned about exposing their email address,
they probably already use a "throw-away" email address to post to the
group.

Please could I request that you change the setting?
What is the reason for this request? Why can't you just use the
private message/email function of the groups.io website?








Re: Obfusctated email adresses in archive

Colin Herbert
 

Oddly enough, I get to see email addresses. At the top of emails is something like:

"TekScopes@groups.io; on behalf of; Harry Houdini <harryhoudini@magicianmail.com>"

I don't understand why, but there you go. I didn't do anything special to get this, perhaps it's because I am in the UK?

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David DiGiacomo
Sent: 22 June 2020 15:08
To: TekScopes
Subject: Re: [TekScopes] Obfusctated email adresses in archive

On Mon, Jun 22, 2020 at 6:53 AM David C. Partridge
<david.partridge@perdrix.co.uk> wrote:

Dennis,

It's possible to change the group settings to not hide email addresses in
the archive. If anyone is concerned about exposing their email address,
they probably already use a "throw-away" email address to post to the group.

Please could I request that you change the setting?
What is the reason for this request? Why can't you just use the
private message/email function of the groups.io website?


Re: Spectrum Analyzer Question

David Berlind
 

Dennis, thank you for helping me to frame my inquiry better. Your guidance is always appreciated. As you probably saw by now, I responded with a summary in which I mentioned that as I further my exploration into electronics, I often don't know what I don't know. So far, with all the answers that I've received, I know so much more and have many avenues to explore that I never even considered before. A year from now, I hope to have experimented with an SDR and/or nanoVNA device, the FFT capability on my TDS 480B, and with any luck, a dedicated spectrum analyzer. Even so, I did not want to leave your questions unanswered as I'm sure I will still see some answers come in that further my education.

Q1) First and most important: Explain what you intend to use a spectrum
analyzer for. Include every single thing it will be used for.
A1: I don't know every single thing that I will use it for. When I acquired my first oscilloscope, I thought I knew the one or two use cases that I'd apply it to. But, as I learn more about electronics, I'm glad to have my oscilloscopes to do experiments that I never thought I'd do (just to further my understanding). It will be the same with spectrum analysis. But at the onset, I am interested in observing a carrier, its sidebands, and harmonics and do some experiments with audio signals. If I'm performing an alignment of an old tube radio, I'd like to make pre and post mixer observations. There are bunch of videos that I've watched on YouTube that I'd like to reproduce in my own lab. Sometimes, these videos work off of a fixed configuration of everything in an effort to fix one DUT. But when I watch these videos, I wonder what would happen if some of the variable inputs were changed. I suspect I know the answer in some cases, but I would enjoy seeing this in my own lab.

Q2) What is the most money you can afford to spend for a spectrum analyzer. Be
specific. Do not say a few hundred dollars.
A2. Right now, I'm going to say $500. I say this based on the responses I have received so far and the understanding that spectrum analyzers are just expensive. However, I do not have $500 right now. My plan is to get my feet wet with some other options and save some proceeds from gear that I have here in the lab that I have to fix and sell. I try to keep my hobbies self-funded. So, it may take me a while to get to $500. But at the same time, it looks like I have some other short term options that will help me to develop a much better understanding. But I will continue to keep my eyes peeled for a viable stand alone unit. If I've learned enything from the gear that I've acquired so far, it's that patience pays. Sooner or later, something will come along.

Q3) What brand of Spectrum Analyzers are you considering? Be specific.
A3. If you recall my first question was really about trying to understand the 7000 plug-in option vs. a stand alone unit given that I have a few 7000-series mainframes here. So, while this started as a Tek specific inquiry, the answers here have taught me to be open to other options. I'm still interested in the plug-in approach but have a better understanding of the risks. I learned about the T1401A which looks like an interesting approach if you already own an oscilloscope but am not clear on its compatibility with all scopes or just one family. I like staying with brands that I can find help for. This forum is one reason I have a lot of Tek stuff. I know that I can get help here and in many cases, if I don't ask a question that I need the answer to, someone else will. Like today, I woke up to a thread about first time startup recommendations for a 545A. I am paying very close attention because I have two 547s here and I'll need to go through the same thing at some point. The availability of the HP/Agilent forum means that that looks like a good brand to keep a watch for too.

Q4) What research have you done to to familiarize yourself with the prices and
availability of spectrum analyzers?
A4: Beyond this thread and some local searches of Craigslist and the Facebook marketplace, none.

Q5) Spectrum Analyzers come in many different physical variants. Which do you
want? Please explain why you chose the ones you did.
A5: If the answers to this thread taught me anything, it's that there are a lot of variants I didn't know about. I know so much more than I did before and am a much more educated consumer as a result. I've yet to establish a preference. This is one of those areas where I don't know what I don't know. For example, when I acquired my first oscilloscope (a Tek 466), I didn't know that oscilloscopes came in 2 and 4 channel versions or why I might need 4 vs 2 channels. Nor did I know there were modular mainframes. Thanks to a member here, I acquired my first mainframe with four channels and was able to simultaneously observe the multiple 90 degree phase shifts of the A/C signal that traverses a guitar amplifier's tremolo circuit. When I first started fixing guitar amps, I didn't even know what phase shift was, much less why a four channel oscilloscope would help me to observe it better than a two channel one.

* A spectrum analyzer plugin. If so what scope does will it plug into?
If I get a plug-in, more than likely a 7603. I also have a 7633 here but it's in my service queue and will be a while before it's ready.

* A portable spectrum analyzer
Maybe. I'd like to keep an open mind.

* A PC based spectrum analyzer, if so, how fast is the PC it will be connected
to?
I own a MacBook Pro. 2.8 Ghz. 16 GB RAM

* A stand alone spectrum analyzer?
Yes, of course I'd be interested in this option.

Again Dennis, thank you for your guidance on this issue. I know some answers were not as specific as they could have been. But I am learning thanks to everyone here and as I learn more, and do more, my desires are sure to clarify themselves.

David


Re: 2% Silver

Colin Herbert
 

"On the same note, ERSIN made a solder called save-a-bit when soldering irons had a copper tip.
They added copper to the alloy to prevent the erosion of the tip from the normal lead/tin alloy.
Glenn"

I think I remember it as Ersin "Savbit". Incidentally, soldering-iron tips are _still_ made from copper, it is just that they are now given a plating of iron, which prevents the copper from being dissolved by the molten solder (allegedly). Such bits should not be filed to renew the tip, because that removes the protective iron plating. The problem is, we all do it when our bits become pitted, but perhaps such filing is limited to the very end of the bit? I suspect that most common solder used in electronics still contains a little copper.

Colin.


Re: 2% Silver

Glenn Little
 

Regular tin/lead solder will leach the silver out of the ceramic, over time.
The silver is added to the alloy to prevent this leaching.
IIRC Tektronix used an alloy with 3% silver.
The common alloy that can be found today is 2% silver.
Serves the same purpose.

On the same note, ERSIN made a solder called save-a-bit when soldering irons had a copper tip.
They added copper to the alloy to prevent the erosion of the tip from the normal lead/tin alloy.

Glenn

On 6/22/2020 8:59 AM, David Kuhn wrote:
" The "silver bearing" solder is akin to soft solder (used in making
electrical joints) and contains a relatively low proportion of silver."

Is that the type that was included inside the old 500 series scopes for
repairs? I understand that regular lead solder was not good for those
ceramic component strips in the scopes? Did it keep the plating from
unbounding to the ceramic? If that roll of solder is missing from the
scopes (and most likely is), what solder should be used for repairs? I
always thought it was some sort of silver solder? It must still contain
lead.

On Mon, Jun 22, 2020 at 7:52 AM Colin Herbert via groups.io <colingherbert=
blueyonder.co.uk@groups.io> wrote:

"Silver Solder" is a hard solder used in making mechanical joints such as
in jewellery. It melts at a relatively high temperature and is akin to
brazing, i.e. "hard soldering". It contains silver, copper and zinc and
maybe a little cadmium to get a lower melting-point. The "silver bearing"
solder is akin to soft solder (used in making electrical joints) and
contains a relatively low proportion of silver.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David
Kuhn
Sent: 22 June 2020 12:32
To: TekScopes@groups.io
Subject: Re: [TekScopes] 2% Silver

"The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope. "

Hello Chuck. I thought they used "silver" solder on those? Is that not
lead free? If not, what does "Silver" solder mean?

Sorry, just curious.

Dave

On Mon, Jun 22, 2020 at 12:07 AM Chuck Harris <cfharris@erols.com> wrote:

The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope.

The Kester Sn62 solder makes beautiful joints, though.

-Chuck Harris

Randy.AB9GO wrote:
I purchased a 1 lb roll of Multicore 2% at of all things a farm
equipment
show 4-5 years ago for $3.00! No one wanted because it was too thin.
You
just never know where stuff like this is going to show up. I will
probably
bite the bullet and buy a new roll when I need it. It makes some of
the
prettiest joints you've ever seen. I use it on everything. On the
other
end of the spectrum is lead free and unless I have to work on something
that is already lead free I'm just not buying it or using it. Awful
awful
stuff.

randy.ab9go@gmail.com







--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"


Re: Obfusctated email adresses in archive

David DiGiacomo
 

On Mon, Jun 22, 2020 at 6:53 AM David C. Partridge
<david.partridge@perdrix.co.uk> wrote:

Dennis,

It's possible to change the group settings to not hide email addresses in
the archive. If anyone is concerned about exposing their email address,
they probably already use a "throw-away" email address to post to the group.

Please could I request that you change the setting?
What is the reason for this request? Why can't you just use the
private message/email function of the groups.io website?


Re: First-time startup for vintage scopes?

Jamie Ostrowski
 

I would also strongly suggest watching "Lazy Electrons" Tektronix
restoration videos for another perspective on how to bring an old Tek scope
up and restore it. He does a really careful job and is very thorough in his
approach and explanations.

Everyone seems to have their own approach, though, but sometimes it is nice
to see how lots of people approach it and then build from all the advice,
taking what you like and spitting out the bones. Even his approach seems to
have variated from one project to successive to some degree. In early
videos he re-capped, and in later ones began re-forming his capacitors.


Tektronix 549:

https://www.youtube.com/watch?v=8rWH-uuf60U


Tektronix 547 Restoration Part I and II:

https://www.youtube.com/watch?v=79yrf7xKsK4

https://www.youtube.com/watch?v=56tqlwQO5uY

He has done a lot of other Tek restorations and documented on his youtube
site:

https://www.youtube.com/channel/UCCNIi7O55ETS5oMxL5oRGng/videos









On Mon, Jun 22, 2020 at 7:53 AM Kurt Rosenfeld <kurt.harlem@gmail.com>
wrote:

Of course we can discuss your specific situation. You might also want to
read some of the discussion threads in this forum's archive, since this
general situation has been discussed many times. Some search terms to use
(in the forum's search box):
"reform"
"variac"

Be sure to read the entire threads to get the full set of perspectives,
full set of things to consider, etc.





Re: 7854/7S11 issue

SCMenasian
 

Ram,

OOps. A typographical error in my previous message. The word, "not" got left out before "actually" in the last sentence

Stephen


Re: 2% Silver

David Holland
 

Yes, It is "leaded" (soft) silver solder.

My understanding is the plating is silver based, and if you dilute the
joint too much, by using un-silvered solder, then the plating will become
unstuck.

This is the stuff I bought for working on silver strips: (I bought mine
from PE, they're local.)

https://www.parts-express.com/wbt-0800-silver-solder-4-silver-content-1-8-lb--093-586

https://www.amazon.com/WBT-0800-Silver-Solder-Content/dp/B00125OCVU

MSDS is here:
https://www.parts-express.com/pedocs/more-info/wbt-08-series-silver-solder-4-percent-silver-content-msds.pdf


Its chock full of Tin, Lead, Silver, Bismuth, Antimony, and Induim. All
the things,a growing ceramic strip needs.... :-)

(Try to ignore the audio-phool verbiage on the PE page. Audio-Phools are
PE's primary market, but I'd rather have them around, catering to them,
than not here at all.)

David

On Mon, Jun 22, 2020 at 9:00 AM David Kuhn <Daveyk021@gmail.com> wrote:

" The "silver bearing" solder is akin to soft solder (used in making
electrical joints) and contains a relatively low proportion of silver."

Is that the type that was included inside the old 500 series scopes for
repairs? I understand that regular lead solder was not good for those
ceramic component strips in the scopes? Did it keep the plating from
unbounding to the ceramic? If that roll of solder is missing from the
scopes (and most likely is), what solder should be used for repairs? I
always thought it was some sort of silver solder? It must still contain
lead.

On Mon, Jun 22, 2020 at 7:52 AM Colin Herbert via groups.io
<colingherbert=
blueyonder.co.uk@groups.io> wrote:

"Silver Solder" is a hard solder used in making mechanical joints such as
in jewellery. It melts at a relatively high temperature and is akin to
brazing, i.e. "hard soldering". It contains silver, copper and zinc and
maybe a little cadmium to get a lower melting-point. The "silver bearing"
solder is akin to soft solder (used in making electrical joints) and
contains a relatively low proportion of silver.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
David
Kuhn
Sent: 22 June 2020 12:32
To: TekScopes@groups.io
Subject: Re: [TekScopes] 2% Silver

"The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope. "

Hello Chuck. I thought they used "silver" solder on those? Is that not
lead free? If not, what does "Silver" solder mean?

Sorry, just curious.

Dave

On Mon, Jun 22, 2020 at 12:07 AM Chuck Harris <cfharris@erols.com>
wrote:

The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope.

The Kester Sn62 solder makes beautiful joints, though.

-Chuck Harris

Randy.AB9GO wrote:
I purchased a 1 lb roll of Multicore 2% at of all things a farm
equipment
show 4-5 years ago for $3.00! No one wanted because it was too
thin.
You
just never know where stuff like this is going to show up. I will
probably
bite the bullet and buy a new roll when I need it. It makes some of
the
prettiest joints you've ever seen. I use it on everything. On the
other
end of the spectrum is lead free and unless I have to work on
something
that is already lead free I'm just not buying it or using it. Awful
awful
stuff.

randy.ab9go@gmail.com












Re: 2% Silver

Matt
 

Reg,

I would like to take you up on your generous offer. I could not figure out your e-mail address so I couldn't PM you.

Thanks!
Matt


Re: 7854/7S11 issue

SCMenasian
 

Ram,

I have 2 7S11s.
For what it's worth, I get the following values using a fluke 87 VOM, taking care to keep the polarity correct.
Unit 1 Unit 2
+15 823 857
+15 DCPL 906 857
-15 2.09k 1.98k
+50 9.01k 8.38k
-50 7.28k 5.98k

Note that the discrepancy in +15 and +15 DCPL values in unit 1
(vs none in unit 2) may be due to a problem in one of the units. I have
actually used them recently.

Stephen


Re: 2% Silver

David Kuhn
 

" The "silver bearing" solder is akin to soft solder (used in making
electrical joints) and contains a relatively low proportion of silver."

Is that the type that was included inside the old 500 series scopes for
repairs? I understand that regular lead solder was not good for those
ceramic component strips in the scopes? Did it keep the plating from
unbounding to the ceramic? If that roll of solder is missing from the
scopes (and most likely is), what solder should be used for repairs? I
always thought it was some sort of silver solder? It must still contain
lead.

On Mon, Jun 22, 2020 at 7:52 AM Colin Herbert via groups.io <colingherbert=
blueyonder.co.uk@groups.io> wrote:

"Silver Solder" is a hard solder used in making mechanical joints such as
in jewellery. It melts at a relatively high temperature and is akin to
brazing, i.e. "hard soldering". It contains silver, copper and zinc and
maybe a little cadmium to get a lower melting-point. The "silver bearing"
solder is akin to soft solder (used in making electrical joints) and
contains a relatively low proportion of silver.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David
Kuhn
Sent: 22 June 2020 12:32
To: TekScopes@groups.io
Subject: Re: [TekScopes] 2% Silver

"The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope. "

Hello Chuck. I thought they used "silver" solder on those? Is that not
lead free? If not, what does "Silver" solder mean?

Sorry, just curious.

Dave

On Mon, Jun 22, 2020 at 12:07 AM Chuck Harris <cfharris@erols.com> wrote:

The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope.

The Kester Sn62 solder makes beautiful joints, though.

-Chuck Harris

Randy.AB9GO wrote:
I purchased a 1 lb roll of Multicore 2% at of all things a farm
equipment
show 4-5 years ago for $3.00! No one wanted because it was too thin.
You
just never know where stuff like this is going to show up. I will
probably
bite the bullet and buy a new roll when I need it. It makes some of
the
prettiest joints you've ever seen. I use it on everything. On the
other
end of the spectrum is lead free and unless I have to work on something
that is already lead free I'm just not buying it or using it. Awful
awful
stuff.

randy.ab9go@gmail.com










Re: First-time startup for vintage scopes?

Kurt Rosenfeld
 

Of course we can discuss your specific situation. You might also want to read some of the discussion threads in this forum's archive, since this general situation has been discussed many times. Some search terms to use (in the forum's search box):
"reform"
"variac"

Be sure to read the entire threads to get the full set of perspectives, full set of things to consider, etc.


Obfusctated email adresses in archive

 

Dennis,

It's possible to change the group settings to not hide email addresses in
the archive. If anyone is concerned about exposing their email address,
they probably already use a "throw-away" email address to post to the group.

Please could I request that you change the setting?

Thanks
David


Re: 2% Silver

Colin Herbert
 

"Silver Solder" is a hard solder used in making mechanical joints such as in jewellery. It melts at a relatively high temperature and is akin to brazing, i.e. "hard soldering". It contains silver, copper and zinc and maybe a little cadmium to get a lower melting-point. The "silver bearing" solder is akin to soft solder (used in making electrical joints) and contains a relatively low proportion of silver.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David Kuhn
Sent: 22 June 2020 12:32
To: TekScopes@groups.io
Subject: Re: [TekScopes] 2% Silver

"The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope. "

Hello Chuck. I thought they used "silver" solder on those? Is that not
lead free? If not, what does "Silver" solder mean?

Sorry, just curious.

Dave

On Mon, Jun 22, 2020 at 12:07 AM Chuck Harris <cfharris@erols.com> wrote:

The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope.

The Kester Sn62 solder makes beautiful joints, though.

-Chuck Harris

Randy.AB9GO wrote:
I purchased a 1 lb roll of Multicore 2% at of all things a farm equipment
show 4-5 years ago for $3.00! No one wanted because it was too thin.
You
just never know where stuff like this is going to show up. I will
probably
bite the bullet and buy a new roll when I need it. It makes some of the
prettiest joints you've ever seen. I use it on everything. On the other
end of the spectrum is lead free and unless I have to work on something
that is already lead free I'm just not buying it or using it. Awful
awful
stuff.

randy.ab9go@gmail.com




Re: 2% Silver

Roy Morgan
 

Reg,

I have a 545B and a 547, and would very much appreciate Getting a bit of the solder.

Thank you for the offer.

Roy Morgan
PO Box 101
Bernardston
MA. 01337

On Jun 21, 2020, at 5:27 PM, Reginald Beardsley via groups.io <pulaskite=yahoo.com@groups.io> wrote:

I bought a spool of 2% silver solder in preparation for reviving a 545, but the 545 went away during a move from Dallas to Houston.

I still have the solder, so if anyone needs a few feet, email me with an address and I'll stick some in an envelope. While it seems highly unlikely I'll need the solder myself, I'm not very good at predicting the future. So I don't want to get rid of the whole roll. But for anyone ...
3 ft should be enough solder.


Re: 2% Silver

David Kuhn
 

"The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope. "

Hello Chuck. I thought they used "silver" solder on those? Is that not
lead free? If not, what does "Silver" solder mean?

Sorry, just curious.

Dave

On Mon, Jun 22, 2020 at 12:07 AM Chuck Harris <cfharris@erols.com> wrote:

The tektronix solder is definitely not lead free, and you definitely
do not want to be using lead free solder on the terminal strips in
a tektronix 500 series scope.

The Kester Sn62 solder makes beautiful joints, though.

-Chuck Harris

Randy.AB9GO wrote:
I purchased a 1 lb roll of Multicore 2% at of all things a farm equipment
show 4-5 years ago for $3.00! No one wanted because it was too thin.
You
just never know where stuff like this is going to show up. I will
probably
bite the bullet and buy a new roll when I need it. It makes some of the
prettiest joints you've ever seen. I use it on everything. On the other
end of the spectrum is lead free and unless I have to work on something
that is already lead free I'm just not buying it or using it. Awful
awful
stuff.

randy.ab9go@gmail.com




Re: 475 questions

Chuck Harris <cfharris@...>
 

It sounds to me like you are using one of those transistor/capacitor/ESR/
SCR/diode/inductor/... testers on in-circuit components.

You shouldn't do that!

These cheap Chinese/Ebay testers are definitely not suitable for in-circuit
testing. Hook a storage scope onto the terminals and look at what they are
doing to the part. They are applying significant voltages, typically ramps
of +/- 5V to the part to see how it behaves, and voltages like that will
activate most of the semiconductor junctions in the scope, and certainly
will be confused by parallel combinations of parts.

The only testers that are truly suitable to use in circuit have to use less
than a diode/transistor junction voltage in their tests, and of course, they
can't test diodes and transistors that way...

ESR meters, like the Dick Smith variety, apply a couple of tens of millivolts
signal to the capacitor at 50KHz to do their testing.

-Chuck Harris

ciclista41 via groups.io wrote:

Hi folks,

Here's where I'm up to. All six large capacitors have been replaced, along with the two tantalums that I pulled, thinking they were bad based on in-circuit tests which turned out to be wrong--they were good. Made sure I had correct polarity.

The large capacitors were good except for C1412 and C1414. C1414 was the worst. It reads 0L on my Fluke 87-V for capacitance (same as shorting the probes together). My "transistor tester" shows it as 12.59 nF with 14% vloss. The C1412 still shows 399 μF (rated 360 μF), but the "tester" shows 347 nF, 6.5 Ω ESR, and 3.8% vloss.

Okay, so in replacing all these, I used Alex Cuoghi's PCB's. I wanted to make sure I hadn't created any shorts due to poor soldering (my soldering looks pretty good to me, but just being careful), so after soldering the four pins into the PCB's, I checked for continuity among the ground pins to the via where the negative of the cap goes, and from the positive pin to the positive via. All good in all cases. Then I soldered the caps in place, followed by a re-checking of appropriate continuities. Finally, I soldered the PCB pins to the A9 board, making sure each was in its appropriate location and rechecking for continuity and no shorting. Then I noticed that I had not replaced the CR1412 rectifier before installing the C1412, so had to pull that again, install the CR1412, then reinstall the C1412 cap. Again checked for appropriate continuity and lack of shorts.

Time to plug the scope in again. I had a 200W bulb in series with the plug as a current limiter. Switched on the scope, and immediately switched it off again, as the bulb lit up brightly and there were sparks at the C1412 where soldered to the board. Sounded like frying bacon, but this is not supposed to be a MIG welder! Figured I had somehow created a short with my soldering, so pulled the C1412 again. No sign of any burning, so sign of solder out of place, everything still looked and measured as expected. Even pulled the cap from the PCB with no sign of anything wrong. Shrugged my shoulders and put it back in the board. Tried again with the same result. Pulled again (I know, poor board, but it seems to be handling it all gracefully). Again, so sign of my having screwed anything up. Let it sit for a day, hoping I'd think of some reason it could be my fault that there was a short. Full disclosure, I may have dropped a screw through the hole in the middle of the bottom of the board, but I don't think so. Turned the scope every which way while shaking it and there was no rattle and nothing fell out. The only other thing I could think of was that I may have cooked the CR1412 with soldering it, but I doubt that, and it did measure as good before I put it back in.

So, I'm guessing that there is a short somewhere in one of the boards, and the fact that the C1414, which is in series with the C1412 that gets so upset when I switch on the scope, was protected from that effect by the fact that the old C1414 measures in the MΩ range, and maybe the short was what killed that capacitor in the first place.

Any ideas?

I don't yet have a Variac, but one should arrive in the mail tomorrow or the next day. Alternatively, I have a DC power supply that is fixed current or fixed voltage with up to 10A and 30V. Not sure where to feed sub 5V into the circuit to try to find the fault. Also I tried pulling all of the power connections to other boards and turning it on, but still got a sizzle at the C1412.

Bruce






Re: 2465B BIOS - D27011 Eprom programming

henasau@...
 

I got hold of Top2005 programmer. It has 27011/27C011 Eprom listed. This programmer is running of USB port but it is only supported as high as Windows XP.
I ordered bunch of 27C011 from Ebay and hopefully I will be able to program them. I wonder if anyone can point me to 2465B BIOS image. There are plenty of DALLAS NVRAM images but I couldn't find any firmware 160-5877-02 images. In an older thread someone mentioned BlueFeatherTech ftp site but I can't get any response.
I sent the message but no reply.
Henryk


Re: 2% Silver

Shirley Dulcey KE1L
 

Bismuth + lead is definitely a no-fly zone. Such an alloy can have a VERY
low melting point, well below 100C, possibly low enough that solder joints
will melt in normal use.

On the other hand, keeping some bismuth solder paste around is very handy
if you ever do rework of modern RoHS boards. SAC305 and similar alloys can
be challenging to rework because of their high melting points. Add a bit of
bismuth and you now have a joint that is easier and safer to rework and
where you can do it without disturbing other nearby solder joints.
Bismuth-based solder doesn't normally contain copper but the presence of
copper in joints is not a problem. The most common alloy is Sn42Bi58; there
are also versions where a small amount of silver is included.

I haven't tried the germanium-doped solder yet. I have been using a
lead-free solder with a bit of antimony for a long time, and I find it a
bit easier to work with than standard SAC305. Mine was a hamfest find years
ago; SparkFun now sells a similar solder.

On Mon, Jun 22, 2020 at 1:21 AM Monty Montgomery <xiphmont@gmail.com> wrote:

On Sun, Jun 21, 2020 at 6:29 PM Randy.AB9GO <randy.ab9go@gmail.com> wrote:
On the other
end of the spectrum is lead free and unless I have to work on something
that is already lead free I'm just not buying it or using it. Awful
awful
stuff.
There's a million different kinds. Some are good enough I don't miss
lead, though time will tell if the joints hold up. Currently trying
out the new germanium doped varieties. Anyone else tried those? And
then, of course, there's bismuth.... Collect a few different types
and you can do four complete hands-off reflow passes to assemble
boards with components on both sides! Useful for hybrid attenuator
assemblies.

Still shouldn't mix any of it though, especially not with leaded joints.

Monty



18041 - 18060 of 186429