Date   

Re: Can capacitors

Mark Goldberg
 

I've rebuilt solid state amplifiers. New technology capacitors, well
chosen, are way better than the old ones. It is easier to choose for
power supply filter caps. In a similar size case you get several times
the capacitance, a fraction of the ESR and higher voltage ratings. You
just need to find a way to fit the new ones mechanically. The only
reason to use old caps is for looks or if the circuit relied on having
crappy caps with high ESR and low capacitance. You may have to limit
the power-up surge current. The result is a better power supply with
better performance at low frequencies.

For caps in the audio chain, you need to choose more judiciously. Some
of the new high capacitance formulations change capacitance with
voltage more, which can cause distortion. But, you can choose better
ones which are available. Being an EE, I've been able to understand
the circuit and choose correctly most of the time.

In general, capacitors are way better now in every way.

Transformers are another matter. Some of the knowledge of how to make
good ones seems to have been lost, but there are still good ones out
there. Again, choose carefully. It is harder to do that in a power
supply where you don't know the design well.

The huge increase in automotive electronics had resulted in better
parts that work over a wider temperature range. I generally design
with -40C to +85C or +125C parts even for commercial designs that may
have used 0 - 70C parts in the past. The high volume and low cost of
automotive rated components is a big plus these days. They are also
better with vibration.

All this applies equally to test equipment.

For discretes and specialized ICs, obsolescence is indeed a problem.
Some smart folks have designed good replacements though with modern
components using a different design.

Regards,

Mark

On Sat, Dec 5, 2020 at 1:22 PM Dave Voorhis <voorhis@gmail.com> wrote:

On 5 Dec 2020, at 20:13, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

… Watch the videos: their whole premise, AFACT, is that because these “vintage" capacitors are manufactured on some... supposedly 1920's salvaged Mallory manufacturing machinery... that will make your "vintage" Fender (et. al.) amplifier sound better.
What's up with that?
Same as all the other audiophoolery around cryogenically treated tubes/valves and wires; capacitors of magic vintage or casing materials and/or colour; strategically room-placed sonically-enhancing crystals; transformers made of solid unobtanium and the like: it sells high-priced products for maximum profit.

The sad part is that some people actually fall for the sellers' ludicrously incredible pseudoscientific claims (and the sellers clearly know this.)





Re: Can capacitors

Roy Thistle
 

On Sat, Dec 5, 2020 at 11:22 AM, greenboxmaven wrote:


The vast majority of failures were drastic reduction or total loss of
capacitance in one or two sections. ESR would also go rather high.
Overheating, shorting, and venting were rare.
Yes... lots of time these Mallory FC type .et al. caps in a can... there was a "drastic reduction or total loss of capacitance in one or two sections" ... often heard in old radios as a loud hum in the speaker. I've heard tell of FCs shorting... (often told as fact on sites selling replacements... and in the lore too... claiming things like tubes and transformers destroyed)... but, I think FCs shorting was quite rare. Old timey service guys... I remember... used to have a good one(s) in their kits... fitted with leads and alligator clips... to bypass suspect FCs.
When we were kids... not so good kids... we used to connect old scavenged FC, in reverse polarity, across old car batteries. Now that was a short!
Similarly, and not much better behaved... we used to spook the lab tech by doing it with those, single value, single-ended radially leaded types (rubber plug, and scored Al top)... were all familiar with.


Re: Can capacitors

Dave Voorhis
 

On 5 Dec 2020, at 20:13, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

… Watch the videos: their whole premise, AFACT, is that because these “vintage" capacitors are manufactured on some... supposedly 1920's salvaged Mallory manufacturing machinery... that will make your "vintage" Fender (et. al.) amplifier sound better.
What's up with that?
Same as all the other audiophoolery around cryogenically treated tubes/valves and wires; capacitors of magic vintage or casing materials and/or colour; strategically room-placed sonically-enhancing crystals; transformers made of solid unobtanium and the like: it sells high-priced products for maximum profit.

The sad part is that some people actually fall for the sellers' ludicrously incredible pseudoscientific claims (and the sellers clearly know this.)


Re: Need a 376-0144-00

 

177 coupler is here:

https://groups.io/g/TekScopes/photo/257571/0?p=Created,,,20,2,0,0

--
Bob Haas


Re: Need a 376-0144-00

 

The vintageTEK Museum has several of what I believe are the 384-1305-00. We ask $10 postpaid. I will post a photo as soon as I figure out how.

--
Bob Haas


Re: Can capacitors

Roy Thistle
 

On Sat, Dec 5, 2020 at 10:02 AM, greenboxmaven wrote:


these condensers do not measure up in reliability
Let's agree (or agree to disagree, if you do) that we can only consider the "reliability" of these things subjectively.
Where is there any objective reliability data published on them?
There's plenty of reliability data for the Mallory FC type capacitors... which these things are being compared to.
Watch the videos: their whole premise, AFACT, is that because these "vintage" capacitors are manufactured on some... supposedly 1920's salvaged Mallory manufacturing machinery... that will make your "vintage" Fender (et. al.) amplifier sound better.
What's up with that?


Re: Can capacitors

Chuck Harris <cfharris@...>
 

Ok, thanks for the info.

Here is what I think is happening:

When you have a current flowing across an electrolyte, with
a pair of aluminum electrodes, the electrolyte builds oxide
on one electrode, and the other stays relatively free of
oxide. This insulates the oxide coated electrode from the
electrolyte, and the current goes away... Not a problem,
that is what is supposed to happen.

But, if you have a current flowing across an electrolyte, with
a pair of dissimilar metal electrodes, such as aluminum and
steel or copper, one will sacrifice the other, depending on
which is the more reactive metal... usually the aluminum.

My guess is they used something like a steel, or copper, rivet
to connect the aluminum ribbon (that comes from the plates) to
the terminals. To protect the rivet, they applied a protective
coating to keep the electrolyte away.

The protective coating failed.

That failure allowed an electrolytic reaction, which caused the
ribbon to be etched through, which left the capacitor essentially
open circuit... low capacitance, and very high ESR.

-Chuck Harris

greenboxmaven via groups.io wrote:

The vast majority of failures were drastic reduction or total loss of capacitance in
one or two sections. ESR would also go rather high.  Overheating, shorting, and
venting were rare. These problems tended to occur more often in higher voltage
sections, 400 volts or more. Condensers that were all 350 volts or less did not fail
very often, but still far more frequently than today's imported single section
condensers.

      Bruce Gentry, KA2IVY


On 12/5/20 13:14, Chuck Harris wrote:
Not to put you on the spot, but can you share with
us the types of failures you witnessed in these new
manufacture can capacitors?

It might allow us to determine what they are doing wrong.

For instance, can capacitors were originally made during
the era where the capacitor's aluminum wasn't pre anodized
before construction.  They anodized it in place by
applying a current limited peak required voltage.

Capacitors built during that era have a much more reactive
(to aluminum) electrolyte, than do current manufacture
capacitors.

There have been many electrolyte failures since the
industrial espionage days when spies from China stole
bogus files detailing one highly regarded manufacturer's
recipe.. and hundreds of Chinese manufacturers, and a
few Japanese, made little time bombs using the purloined
recipe...

-Chuck Harris

greenboxmaven via groups.io wrote:
I agree that, regrettably, these condensers do not measure up in reliability. I
worked at a sound equipment boutique and  had about a 10% failure rate of these
condensers within three years.   They are also quite expensive, which is justified by
the small production volume and labor of making them.  I have two old sound
amplifiers of my own that had these condensers installed before I got them, and they
have all failed less than ten years after they were made. I hope the manufacturers
will take these statistics seriously and improve their quality. Meanwhile, I will
continue opening old ones, removing the failed windings, and replacing them with
modern individual condensers.

      Bruce Gentry, KA2IVY


On 12/5/20 11:55, Roy Thistle wrote:
On Sat, Dec  5, 2020 at 07:40 AM, Tom Phillips wrote:

There is a video series on the page at www.cemfg.com < http://www.cemfg.com/ >
which shows the can cap manufacturing process using the old Mallory equipment.
It is interesting. The materials handling and process quality control are, of
course, not up to modern standards and the resulting caps are not as reliable
as the original Mallory parts. However, they have been successful with their
niche market customers.














Re: Replacing Can Capacitors 400 series scopes

Craig Cramb
 

To ensure that ALL the solder on both sides of the main board is molten, I
used a Weller 100/140 gun along with the de-solder tip.

Maybe add some chipquick to lower the melting point.
Stock up on PCB repair materials :-)

Thanks guys for you assistance. I’ve worked at these over the years and never been happy with the results. Sometimes it is a total disaster, but usually yes very difficult. I have also done the desolder wand and then an additional solder wand at the same time but it just seems trying to get it warm enough can cause the barrel between the traces to get too hot and separate from board traces and possibly come out with the capacitor tab. Maybe I’m running my irons too hot. Which then is repair parts time. I’ve never tried to locate these repair parts as now sure what that barrel piece is really called.


Re: Can capacitors

greenboxmaven
 

I think heat is a factor. Many classic sound amplifiers are rather compact, and the condensers do get hot. However, the originals withstood it well for decades before becoming unusable. The main failure of older ones was overheating, excess leakage that will not decrease with time, and often spectacular venting. Excessive hum or poor decoupling action were not that common in the equipment I restored. Some coupling condensers in tube sound gear were notorious for leakage, and were replaced pre-emptively. On the other hand, loss of capacitance was the number one failure of electrolytics in solid state gear, I can only recall one incedence of venting, and it was quite spectacular and loud. Repacing all of the electrolytics would transform a solid state amplifier or receiver from mediocre to excellent.

Bruce Gentry, KA2IVY

On 12/5/20 13:44, Ed Breya via groups.io wrote:
Could a high failure rate be attributed to operating temperature? I'd think many of the replacements - at least the higher voltage ones - were used in tube audio and such, and maybe had pretty hot environments, or got cooked by being too close to power tubes.

Ed





Re: Replacing Can Capacitors 400 series scopes

Tad
 

I've replaced hundreds of PS filter caps over the years using high quality
de-soldering equipment.
To ensure that ALL the solder on both sides of the main board is molten, I
used a Weller 100/140 gun along with the de-solder tip.
After sucking up all the molten solder, the dead cap always dropped out on
the bench, leaving nice, clean holes for the new cap.
A little practice goes a long way....


Re: Can capacitors

greenboxmaven
 

The vast majority of failures were drastic reduction or total loss of capacitance in one or two sections. ESR would also go rather high. Overheating, shorting, and venting were rare. These problems tended to occur more often in higher voltage sections, 400 volts or more. Condensers that were all 350 volts or less did not fail very often, but still far more frequently than today's imported single section condensers.

Bruce Gentry, KA2IVY

On 12/5/20 13:14, Chuck Harris wrote:
Not to put you on the spot, but can you share with
us the types of failures you witnessed in these new
manufacture can capacitors?

It might allow us to determine what they are doing wrong.

For instance, can capacitors were originally made during
the era where the capacitor's aluminum wasn't pre anodized
before construction. They anodized it in place by
applying a current limited peak required voltage.

Capacitors built during that era have a much more reactive
(to aluminum) electrolyte, than do current manufacture
capacitors.

There have been many electrolyte failures since the
industrial espionage days when spies from China stole
bogus files detailing one highly regarded manufacturer's
recipe.. and hundreds of Chinese manufacturers, and a
few Japanese, made little time bombs using the purloined
recipe...

-Chuck Harris

greenboxmaven via groups.io wrote:
I agree that, regrettably, these condensers do not measure up in reliability. I
worked at a sound equipment boutique and had about a 10% failure rate of these
condensers within three years. They are also quite expensive, which is justified by
the small production volume and labor of making them. I have two old sound
amplifiers of my own that had these condensers installed before I got them, and they
have all failed less than ten years after they were made. I hope the manufacturers
will take these statistics seriously and improve their quality. Meanwhile, I will
continue opening old ones, removing the failed windings, and replacing them with
modern individual condensers.

Bruce Gentry, KA2IVY


On 12/5/20 11:55, Roy Thistle wrote:
On Sat, Dec 5, 2020 at 07:40 AM, Tom Phillips wrote:

There is a video series on the page at www.cemfg.com < http://www.cemfg.com/ >
which shows the can cap manufacturing process using the old Mallory equipment.
It is interesting. The materials handling and process quality control are, of
course, not up to modern standards and the resulting caps are not as reliable
as the original Mallory parts. However, they have been successful with their
niche market customers.








Re: Can capacitors

Ed Breya
 

Could a high failure rate be attributed to operating temperature? I'd think many of the replacements - at least the higher voltage ones - were used in tube audio and such, and maybe had pretty hot environments, or got cooked by being too close to power tubes.

Ed


Re: 465 B sweep switch cam

Dave Peterson
 

Hi Bob,
Thanks for the offer, but I think my topic title was misleading, and I can't change it now. It should say 465 "B-sweep" switch cam. Meaning the B Time/Div switch on a 465 scope.
I'm new to the who universe of vintage Tek restoration. I'm certainly familiar with these portables from my Army and engineering career as a user, but that's a far cry from knowing them from an restoration perspective. So pardon my large ignorance for everything from history to terminology. I don't know the proper term to use for this component that's clear to everyone. I have a lot to learn.
I'm going through the Vintage Tek Museum right now. It's good to know you guys are a potential source for parts. Looks like I have a lot to review in your eBay store too.
Looking at the map I see you're about a mile away from where I used to live in Beaverton! Wow. Certainly worth a visit in the future. Once we have this whole COVID thing behind us.
Thanks again for the offer. Hope to talk to you more in the future.Dave

On Saturday, December 5, 2020, 09:07:16 AM PST, robeughaas@gmail.com <robeughaas@gmail.com> wrote:

The vintageTEK Museum has a complete 465B timing board assembly, part number 670-6001-01. We are asking $40 postpaid. Please contact me off-board if you are interested.

--
Bob Haas


Re: Can capacitors

Chuck Harris <cfharris@...>
 

Not to put you on the spot, but can you share with
us the types of failures you witnessed in these new
manufacture can capacitors?

It might allow us to determine what they are doing wrong.

For instance, can capacitors were originally made during
the era where the capacitor's aluminum wasn't pre anodized
before construction. They anodized it in place by
applying a current limited peak required voltage.

Capacitors built during that era have a much more reactive
(to aluminum) electrolyte, than do current manufacture
capacitors.

There have been many electrolyte failures since the
industrial espionage days when spies from China stole
bogus files detailing one highly regarded manufacturer's
recipe.. and hundreds of Chinese manufacturers, and a
few Japanese, made little time bombs using the purloined
recipe...

-Chuck Harris

greenboxmaven via groups.io wrote:

I agree that, regrettably, these condensers do not measure up in reliability. I
worked at a sound equipment boutique and  had about a 10% failure rate of these
condensers within three years.   They are also quite expensive, which is justified by
the small production volume and labor of making them.  I have two old sound
amplifiers of my own that had these condensers installed before I got them, and they
have all failed less than ten years after they were made. I hope the manufacturers
will take these statistics seriously and improve their quality. Meanwhile, I will
continue opening old ones, removing the failed windings, and replacing them with
modern individual condensers.

     Bruce Gentry, KA2IVY


On 12/5/20 11:55, Roy Thistle wrote:
On Sat, Dec  5, 2020 at 07:40 AM, Tom Phillips wrote:

There is a video series on the page at www.cemfg.com < http://www.cemfg.com/ >
which shows the can cap manufacturing process using the old Mallory equipment.
It is interesting. The materials handling and process quality control are, of
course, not up to modern standards and the resulting caps are not as reliable
as the original Mallory parts. However, they have been successful with their
niche market customers.








Re: Replacing Can Capacitors 400 series scopes

Paul Amaranth
 

Take the can apart from the top side leaving the pins in the board, then you can more easily desolder them.

It's a pain no matter which way you do it.

Maybe add some chipquick to lower the melting point.

Stock up on PCB repair materials :-)

Paul

On Sat, Dec 05, 2020 at 10:04:06AM -0800, Craig Cramb wrote:
Wondering if anyone would care to pass along tips for removal of the larger can capacitors in equipment such as the 400 series power supply section. There are large quantities of solder and seems to take a lot of heat and easy to damage the traces thru pins between the upper and lower sections. I currently have good desolder equipment but still seem to have an issue getting all the solder out of the holes to disconnect from upper and lower traces without overheating them.







!DSPAM:5fcbcba7219208873113387!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Replacing Can Capacitors 400 series scopes

Craig Cramb
 

Wondering if anyone would care to pass along tips for removal of the larger can capacitors in equipment such as the 400 series power supply section. There are large quantities of solder and seems to take a lot of heat and easy to damage the traces thru pins between the upper and lower sections. I currently have good desolder equipment but still seem to have an issue getting all the solder out of the holes to disconnect from upper and lower traces without overheating them.


Re: Can capacitors

greenboxmaven
 

I agree that, regrettably, these condensers do not measure up in reliability. I worked at a sound equipment boutique and had about a 10% failure rate of these condensers within three years. They are also quite expensive, which is justified by the small production volume and labor of making them. I have two old sound amplifiers of my own that had these condensers installed before I got them, and they have all failed less than ten years after they were made. I hope the manufacturers will take these statistics seriously and improve their quality. Meanwhile, I will continue opening old ones, removing the failed windings, and replacing them with modern individual condensers.

Bruce Gentry, KA2IVY

On 12/5/20 11:55, Roy Thistle wrote:
On Sat, Dec 5, 2020 at 07:40 AM, Tom Phillips wrote:

There is a video series on the page at www.cemfg.com < http://www.cemfg.com/ >
which shows the can cap manufacturing process using the old Mallory equipment.
It is interesting. The materials handling and process quality control are, of
course, not up to modern standards and the resulting caps are not as reliable
as the original Mallory parts. However, they have been successful with their
niche market customers.


Re: 465 B sweep switch cam

 

The vintageTEK Museum has a complete 465B timing board assembly, part number 670-6001-01. We are asking $40 postpaid. Please contact me off-board if you are interested.

--
Bob Haas


Re: Can capacitors

Roy Thistle
 

On Sat, Dec 5, 2020 at 07:40 AM, Tom Phillips wrote:


There is a video series on the page at www.cemfg.com < http://www.cemfg.com/ >
which shows the can cap manufacturing process using the old Mallory equipment.
It is interesting. The materials handling and process quality control are, of
course, not up to modern standards and the resulting caps are not as reliable
as the original Mallory parts. However, they have been successful with their
niche market customers.
The OP cross posted this to the HP-x-x-equipment group.
If you watch the videos... it's all a lot dumber than it looks.
"However, they have been successful with their niche market customers." I agree with Tom's statement...it seems they have been... because there is obviously some money behind it. (Those videos aren't cheap to make... and actors cost money.)
But, I wonder how the people who buy this stuff find their way back home, at night... it must be on instinct... it sure isn't on clear thinking and good understanding.


Re: Historical Analog Scope Triggering Techniques

Tom Gardner
 

Just so.

With logic analysers there is always the issue of whether the logic analyser's input stages are /interpreting/ the /analogue/ waveform in the same way that the actual UUT's input stages are interpreting that analogue waveform. A classic example might be an open collector output that is "slowly drifting" high, and the inputs have different threshold levels and response times, but there are many many other examples.

That's where a scope is useful to assure signal integrity. Once assured, flip to the digital domain.

On 05/12/20 16:05, Harvey White wrote:
I designed something that looked at I2C signals (0-3.3 or 0-5.0 volt TTL typically, but open collector).  The simulation worked fine, but the design didn't.  The real world signal wasn't perfect, the simulator assumed perfection.  The logic analyzer said, with very little problem, "it doesn't work".

I will say that simulation always needs to be done, but the truism is that simulation is only as good as the model.

Harvey


On 12/5/2020 3:11 AM, Tom Gardner wrote:
A simulator should show you the timing range of digital signals, which can be experimentally verified with a logic analyser.

For the corresponding analogue waveforms, simulation requires the i/o IBIS models plus a Spice, and verified with an oscilloscope.


On 05/12/20 01:02, Harvey White wrote:
I remember trying that, and yes, the restrictions are relaxed.  I think it needs either some extra pins to get the signal out or something that uses the programmer.

I sometimes use extra pins for signal tapoffs, and that's after I've simulated it.  Be aware that the simulator generates *perfect* signals and does very little to simulate a real world input.

Harvey


On 12/4/2020 7:18 PM, Tom Gardner wrote:
On 04/12/20 20:54, Dave Peterson via groups.io wrote:
Caveat: I'm a circuit designer by background. I've been pushing CMOS W&L values around my whole career, so I'm no Verilog/System expert.

However, I am a design engineer at Xilinx and have dabbled a little in our software, Vivado. My understanding is that there is a lot of soft IP that comes included with the SW, including logic analyzers. And when it comes to logic analyzers, I only know that they exist and can guess their purpose and functions to some order. I'll have to take a look at this link above, and this thread gets my head going on possible "projects". For example, they love for us to get to know our products at a user level, and do things like giving us a mini Arduino-like system. Like a Raspberry-PI. I wonder if I can install the above on it. Or look at existing LAs included and see what they can and can't do. But then there's the 23 other "projects" I have going on.

As noted by Tom above: "there is a steep learning curve w.r.t. both the HDL and the toolchain." The system level and toolchain are typically what keep me from getting into this, not the underlying code. Could be fun to bridge the worlds of my past and present.
For Xilinx, the search term is "ChipScope". It is intended to enable you to debug internal nodes in your design, but not much imagination  is necessary to see how it could be used for external nodes.

I've lost track of how to what extent it can be freely inserted in your design, but ISTR they relaxed the requirements a year or so ago.

I presume other manufacturers have a similar "product".

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