Digest for sci.electronics.repair@googlegroups.com - 13 updates in 2 topics

9:40 AM Penedão 0 comments
bitrex <user@example.net>: Apr 22 12:00AM -0400

On 4/21/2021 8:41 PM, John Robertson wrote:
 
> Where's the fun in that? As I said, I know I can still get new tubes.
> The problem is the system doesn't work well...
 
> John ;-#)#
 
There's this patent from '66 that describes a solid-state thyratron
replacement:
 
<https://patentimages.storage.googleapis.com/42/6a/0d/6e35c415a3f0e0/US3293449.pdf>
 
It uses a couple of SCRs. It's to replace high-power thyratrons but I
don't see why it couldn't be scaled-down.
bitrex <user@example.net>: Apr 22 12:04AM -0400

On 4/21/2021 8:41 PM, John Robertson wrote:
 
> Where's the fun in that? As I said, I know I can still get new tubes.
> The problem is the system doesn't work well...
 
> John ;-#)#
 
What's a "Wall-o-Matic"?
bitrex <user@example.net>: Apr 22 01:07AM -0400

On 4/21/2021 3:47 PM, John Robertson wrote:
 
> This controlled a solenoid at around 24VAC or regulated (0A2 = -150VDC)
> power supply for the tormat write-in and readout circuits.
 
> John :-#)#
 
I can't find a solid reference on what the gas in the 2D21 is, anyway.
Only few references from the time period I can find don't agree, one
paper says it's hydrogen:
 
<https://books.google.com/books?id=IdB5E4STz5kC&lpg=RA5-PA37&ots=T6ZN06aJWy&dq=hydrogen%20in%202d21&pg=RA5-PA37#v=onepage&q=hydrogen%20in%202d21&f=false>
 
Another says it's xenon:
 
<http://phylab.fudan.edu.cn/lib/exe/fetch.php?media=exp:ajp000701.pdf>
bitrex <user@example.net>: Apr 22 01:14AM -0400

On 4/22/2021 1:07 AM, bitrex wrote:
 
> <https://books.google.com/books?id=IdB5E4STz5kC&lpg=RA5-PA37&ots=T6ZN06aJWy&dq=hydrogen%20in%202d21&pg=RA5-PA37#v=onepage&q=hydrogen%20in%202d21&f=false>
 
> Another says it's xenon:
 
> <http://phylab.fudan.edu.cn/lib/exe/fetch.php?media=exp:ajp000701.pdf>
 
Maybe a mixture of stuff.
bitrex <user@example.net>: Apr 22 02:43AM -0400

On 4/22/2021 1:07 AM, bitrex wrote:
 
> <https://books.google.com/books?id=IdB5E4STz5kC&lpg=RA5-PA37&ots=T6ZN06aJWy&dq=hydrogen%20in%202d21&pg=RA5-PA37#v=onepage&q=hydrogen%20in%202d21&f=false>
 
> Another says it's xenon:
 
> <http://phylab.fudan.edu.cn/lib/exe/fetch.php?media=exp:ajp000701.pdf>
 
I think it must be xenon, the first one is just wrong
DecadentLinuxUserNumeroUno@decadence.org: Apr 22 08:04AM

bitrex <user@example.net> wrote in
 
>> In case you missed it, he was backing me up.
 
> I would hope so! You're team lead, now
 
No... According to the LarkinPunk, I am a mere "technician" who
"hates the magic" of engineers.
piglet <erichpwagner@hotmail.com>: Apr 22 10:04AM +0100

On 22/04/2021 5:00 am, bitrex wrote:
 
> <https://patentimages.storage.googleapis.com/42/6a/0d/6e35c415a3f0e0/US3293449.pdf>
 
> It uses a couple of SCRs. It's to replace high-power thyratrons but I
> don't see why it couldn't be scaled-down.
 
Thanks Bitrex, that patent even mentions a tunnel diode and UJT which
are now very exotic devices. The struggle was to emulate the high
impedance thyratron grid. It seems to me (I have never seen a thyratron)
that a modern depletion mode mosfet would make a good front-end to a SCR
in that a negative grid bias is required to keep the device
non-conducting (if I understand thyratrons correctly).
 
Here is a conceptual sketch:
 
<https://www.dropbox.com/s/al1b8hj07i7jfpq/SED_Thyratron_Idea.pdf?dl=0>
 
Possible fets could be BSS126 or LND150 and SCR with sensitive gates
X0402NF or BT149G.
 
piglet
bitrex <user@example.net>: Apr 22 09:21AM -0400

On 4/22/2021 5:04 AM, piglet wrote:
> that a modern depletion mode mosfet would make a good front-end to a SCR
> in that a negative grid bias is required to keep the device
> non-conducting (if I understand thyratrons correctly).
 
Well Fig 2 in the patent doesn't look like it requires anything exotic,
the exotics look to be included in the "further embodiment of the invention"
 
 
> Possible fets could be BSS126 or LND150 and SCR with sensitive gates
> X0402NF or BT149G.
 
> piglet
 
Yeah, depletion mode MOSFET seems a plausible modern take on it. Only
thing is a real gas thyratron the anode current is controlled by the
control grid current when it's in the low impedance ionized state. In
many switching applications though I expect this doesn't matter too much
it doesn't matter what the impedance is in that state exactly, just so
long as it's low enough to reliably fire the relay or whatever.
 
And there doesn't need to be an analog to the screen grid, when the tube
is used like a switch to ground it's usually connected to the cathode
and just prevents the thyratron from firing until the positive-going
pulse on the control grid is seen. You can see in a 2D21 a box-like
structure surrounding all the other electrodes and I believe that whole
structure is connected to the screen grid pin.
bitrex <user@example.net>: Apr 22 09:35AM -0400


>> I would hope so! You're team lead, now
 
> No... According to the LarkinPunk, I am a mere "technician" who
> "hates the magic" of engineers.
 
Sounds like you have something to prove. Sometimes when I'm helping the
little ol' lady in the library do her taxes some kid shows up with
something to prove too and is like "No dummy you're doing that all
wrong" and then I say "Okay.." and hand the job off directly to him, let
him spend the next two hours with her while I go about my day. I'm not
going to fight him on it he is the white-knight expert who has appeared
in our time of most need. And it makes Ethel very happy!
 
But that's interesting about the line voltage it seems to be a common
misconception and 1954 was a long time before I was born. In any case my
thoughts on the 2D21-dying issue have changed it's not hydrogen-filled
it's probably primarily xenon. Hydrogen-filled thyratrons are more
temperature-sensitive to both the temperature of the heater and
temperature of the glass if they're too hot all the hydrogen tries to
run away or react with the hot cathode. Obviously xenon won't react with
the internal elements or the getter but it can still be absorbed by the
glass or escape where the pins come in.
 
So I still think the reason they end up malfunctioning in service is
that the gas is escaping or being absorbed by the glass and reducing the
operating temperature of the cathode may extend their life.
bitrex <user@example.net>: Apr 22 09:48AM -0400

On 4/22/2021 9:21 AM, bitrex wrote:
 
> Well Fig 2 in the patent doesn't look like it requires anything exotic,
> the exotics look to be included in the "further embodiment of the
> invention"
 
Oh okay I see what you're saying, instead of using a high-impedance SCR
as the first element in a two-SCR pair there are better devices to solve
that "struggle" of the inventor, now.
jlarkin@highlandsniptechnology.com: Apr 22 09:14AM -0700

On Wed, 21 Apr 2021 12:44:37 -0700, John Robertson <spam@flippers.com>
wrote:
 
>Control Center:
 
>https://www.flippers.com/pdfs/Seeburg_V200_Pg_5113-5143_B&W.pdf
 
>Relevant schematic is on page 5128 (pg 16 or the PDF).
 
Yikes. The tube pins all go to off-page connectors, so it's not easy.
 
 
 
--
 
John Larkin Highland Technology, Inc
 
The best designs are necessarily accidental.
amdx <amdx@knology.net>: Apr 22 11:40AM -0500

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
HW <none@no.no>: Apr 22 02:53PM +0200

On Wed, 21 Apr 2021 01:05:27 -0000 (UTC), bob prohaska
 
>What about "oscilloscopes" based on USB sound cards?
 
From what I understand, most people who have tried both, prefer a
standalone scope over a PC based one.
 
>in the $200-500 range.
 
You can get a very nice, brand new, hobby scope for that kind of
money. The Rigol DS1054Z seems to be available for around $450. That
is a four-channel, 50 MHz scope. It can easily be hacked for 100 MHz
bandwidth.
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Digest for sci.electronics.repair@googlegroups.com - 25 updates in 1 topic

8:43 PM Penedão 0 comments
John Robertson <spam@flippers.com>: Apr 21 10:28AM -0700

In my field of arcade repairs we run into older jukeboxes - one
particular model which uses the 2D21 tube and was from about 1954.
 
I have the spec sheet here:
 
https://www.flippers.com/pdfs/2D21_Thyratron_tube.pdf
 
It would be fun to make a solid state replacement for it as nothing
seems to exist. These tubes are still available from several sources,
but they get wonky with age.
 
Being able to simply wire in a TRIAC or SCR (with appropriate bits of
electronic glue) to remove this tube from the suspect list when
servicing this classic Seeburg V200 jukebox would simplify future
servicing. I always like to make things easier for the next tech to work
on machines that passed through my shop...
 
I should point out that Seeburg only used these 2D21s (three 2D21s used)
on their very first control center for their Tormat (200 x magnetic
cores) memory and dropped it like a hot potato. There were numerous
service bulletins culminating in the factory providing a low cost
replacement for the control centers that used 2D21s (three of these) and
the replacement used a single 2050 tube and was a very reliable design.
Not everyone took advantage of the program and all these replacement
were used up long, long ago.
 
John :-#)#
 
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
bitrex <user@example.net>: Apr 21 01:48PM -0400

On 4/21/2021 1:28 PM, John Robertson wrote:
> Not everyone took advantage of the program and all these replacement
> were used up long, long ago.
 
> John :-#)#
 
What happens to them as they age? is that with respect to the unused NOS
types?
 
I was under the impression that small-signal gas thyratrons were very
reliable in service. They're much less temperature sensitive in service
than solid state devices, at least. If you blast a relaxation oscillator
made with a 2D21 with cold spray it barely drifts.
"Peter W." <peterwieck33@gmail.com>: Apr 21 10:49AM -0700

I may have a few of either floating about in my junk boxes. If so, I would be glad to send all that I have to you as I have no discernable use for them. I seem to remember those numbers,
 
Gratis, of course. I will let you know.
 
Peter Wieck
Melrose Park, PA
John Robertson <spam@flippers.com>: Apr 21 10:53AM -0700

On 2021/04/21 10:48 a.m., bitrex wrote:
> reliable in service. They're much less temperature sensitive in service
> than solid state devices, at least. If you blast a relaxation oscillator
> made with a 2D21 with cold spray it barely drifts.
 
The 2D21 tubes become erratic, sometimes they respond, sometimes they
are slow (the solenoid grumbles as it sluggishly engages), and sometimes
they just ignore the control signal. Yet these tubes test OK on my
mutual conductance tube checker (of course).
 
John :-#)#
 
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
bitrex <user@example.net>: Apr 21 01:57PM -0400

On 4/21/2021 1:53 PM, John Robertson wrote:
> they just ignore the control signal. Yet these tubes test OK on my
> mutual conductance tube checker (of course).
 
> John :-#)#
 
Maybe the hydrogen is out-gassing thru the glass over time?
bitrex <user@example.net>: Apr 21 02:02PM -0400

On 4/21/2021 1:53 PM, John Robertson wrote:
> they just ignore the control signal. Yet these tubes test OK on my
> mutual conductance tube checker (of course).
 
> John :-#)#
 
The tube tester can test for conductance from thermionic emission but
IDK if it can test for the conductance when the tube is operating in the
ionization-cascade mode.
John Larkin <jlarkin@highland_atwork_technology.com>: Apr 21 11:14AM -0700

On Wed, 21 Apr 2021 10:28:02 -0700, John Robertson <spam@flippers.com>
wrote:
 
>Not everyone took advantage of the program and all these replacement
>were used up long, long ago.
 
>John :-#)#
 
Got a schematic? It might be easy.
John Larkin <jlarkin@highland_atwork_technology.com>: Apr 21 11:18AM -0700


>The tube tester can test for conductance from thermionic emission but
>IDK if it can test for the conductance when the tube is operating in the
>ionization-cascade mode.
 
A tube tester may not apply enough voltage or current capability to
fire the gas, so would miss a problem with ionization.
 
What's the Gm of a thyratron anyhow?
 
One could build a simple thyratron tester.
bitrex <user@example.net>: Apr 21 02:19PM -0400

On 4/21/2021 2:14 PM, John Larkin wrote:
>> were used up long, long ago.
 
>> John :-#)#
 
> Got a schematic? It might be easy.
 
The 1954 gear was probably designed to run on old-timey line voltage of
~110 AC. Dialing back the heater voltage on the thyratrons to compensate
for higher modern AC supply voltage might extend their life.
bitrex <user@example.net>: Apr 21 02:50PM -0400

On 4/21/2021 1:53 PM, John Robertson wrote:
> they just ignore the control signal. Yet these tubes test OK on my
> mutual conductance tube checker (of course).
 
> John :-#)#
 
Hydrogen diffusion through thin glass within tube-like operating
temperatures, where the gas is in thermal equilibrium with the glass and
the mean free path is >> glass thickness is dominated by e^(-1/T), so if
hydrogen outgassing is causing the erratic behavior whether the tube
envelope temperature is run before the "knee" or after may have a lot to
do with the expected service life.
bitrex <user@example.net>: Apr 21 02:52PM -0400

On 4/21/2021 2:50 PM, bitrex wrote:
 
> Hydrogen diffusion through thin glass within tube-like operating
> temperatures, where the gas is in thermal equilibrium with the glass and
> the mean free path is >> glass thickness
 
I may have the pac-mans backwards there don't quote me on that. :)
bitrex <user@example.net>: Apr 21 03:11PM -0400

On 4/21/2021 2:18 PM, John Larkin wrote:
 
> A tube tester may not apply enough voltage or current capability to
> fire the gas, so would miss a problem with ionization.
 
> What's the Gm of a thyratron anyhow?
 
Thyratron anode conductance is grid current-controlled when in the
ionization mode, you can read off the parameters from fig 2 of the 2D21
datasheet. For grid 1 voltages between about -1 and -5 volts and Ib
between 25 and 200 mA it's vaguely linear at about 50mA per 1 mA.
 
John Robertson <spam@flippers.com>: Apr 21 12:44PM -0700

On 2021/04/21 11:14 a.m., John Larkin wrote:
>> were used up long, long ago.
 
>> John :-#)#
 
> Got a schematic? It might be easy.
 
A fairly recent scan (not tidied up) of my files section for the V200
Control Center:
 
https://www.flippers.com/pdfs/Seeburg_V200_Pg_5113-5143_B&W.pdf
 
Relevant schematic is on page 5128 (pg 16 or the PDF).
 
The first control center is the original TSR1-L6, later it shows the
replacement control center the TSR3-L6.
 
You can ignore the stepper section, that is the interface to allow booth
boxes (called Wall Boxes in the industry) - but it doesn't matter unless
one is using those remote selectors...
 
Thanks for looking at this!
 
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
John Robertson <spam@flippers.com>: Apr 21 12:47PM -0700

On 2021/04/21 11:19 a.m., bitrex wrote:
 
> The 1954 gear was probably designed to run on old-timey line voltage of
> ~110 AC. Dialing back the heater voltage on the thyratrons to compensate
> for higher modern AC supply voltage might extend their life.
 
This controlled a solenoid at around 24VAC or regulated (0A2 = -150VDC)
power supply for the tormat write-in and readout circuits.
 
John :-#)#
 
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
"ohg...@gmail.com" <ohger1s@gmail.com>: Apr 21 01:05PM -0700

On Wednesday, April 21, 2021 at 1:28:10 PM UTC-4, John Robertson wrote:
> the replacement used a single 2050 tube and was a very reliable design.
> Not everyone took advantage of the program and all these replacement
> were used up long, long ago.
 
Designing a workaround would be easier from the standpoint of seeing exactly how it's wired in a circuit as opposed to making a general sub for that tube. Is there a schematic on-line anywhere?
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat>: Apr 21 05:20PM -0400

On Wed, 21 Apr 2021 12:44:37 -0700, John Robertson <spam@flippers.com>
wrote:
 
>Control Center:
 
>https://www.flippers.com/pdfs/Seeburg_V200_Pg_5113-5143_B&W.pdf
 
>Relevant schematic is on page 5128 (pg 16 or the PDF).
 
A thyratron is similar to an SCR, maybe a sensitive-gate type like
2N5064 could be made to work. This one is apparently Xenon-filled.
 
http://www.r-type.org/pdfs/2d21.pdf
 
https://www.mouser.ca/datasheet/2/308/2N5060_D-110409.pdf
 
I don't have the relationships of the thyratron grids in my head
though, never designed with one (I once fixed a spot welder that had
an enormous lethal-looking high voltage thyratron tube (cap on the
top) and a giant step-down transformer to give the kA pulse).
Hardly touched vacuum tubes after HS, for that matter.
--
Best regards,
Spehro Pefhany
bitrex <user@example.net>: Apr 21 06:49PM -0400

On 4/21/2021 5:20 PM, Spehro Pefhany wrote:
> an enormous lethal-looking high voltage thyratron tube (cap on the
> top) and a giant step-down transformer to give the kA pulse).
> Hardly touched vacuum tubes after HS, for that matter.
 
Between the forces of good and the Evil Empire they must have made
bajillions of these things. Why OP not buy a gross from Russia? Just
sitting in their boxes in a dry environment the shelf life might be
measured in centuries.
 
<https://www.ebay.com/itm/274314016219?hash=item3fde63b5db:g:T38AAOSwgOpeqBXp>
John Robertson <spam@flippers.com>: Apr 21 05:41PM -0700

On 2021/04/21 3:49 p.m., bitrex wrote:
> sitting in their boxes in a dry environment the shelf life might be
> measured in centuries.
 
> <https://www.ebay.com/itm/274314016219?hash=item3fde63b5db:g:T38AAOSwgOpeqBXp>
 
Where's the fun in that? As I said, I know I can still get new tubes.
The problem is the system doesn't work well...
 
John ;-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
"Edward Rawde" <invalid@invalid.invalid>: Apr 21 09:30PM -0400

"John Robertson" <spam@flippers.com> wrote in message
news:EKmdnXgYE4CpWx39nZ2dnUU7-Q3NnZ2d@giganews.com...
.....
 
>> <https://www.ebay.com/itm/274314016219?hash=item3fde63b5db:g:T38AAOSwgOpeqBXp>
 
> Where's the fun in that? As I said, I know I can still get new tubes. The
> problem is the system doesn't work well...
 
I had a look at the pdf and the schematic looks like a typical work of art
from that era.
 
So you could probably get a solid state equivalent designed if you wanted to
pay a designer with the necessary experience to do it.
I'm not offering but I'd need the hardware in the same room as me to have
any chance.
 
DecadentLinuxUserNumeroUno@decadence.org: Apr 22 01:31AM

bitrex <user@example.net> wrote in
 
>> Got a schematic? It might be easy.
 
> The 1954 gear was probably designed to run on old-timey line
> voltage of ~110 AC.
 
110 VAC went away at the beginning of the 20th century. By 1950
120 Volts was the standard. The MONIKER remained, but the voltage
has been 120 VAC for a VERY long time.
 
> Dialing back the heater voltage on the
> thyratrons to compensate for higher modern AC supply voltage might
> extend their life.
 
The line voltage was already 120 Volts by then. You need a
remedial electrical system / electronics industry history course.
 
Or maybe you would simply develop enough Internet skills to know
how to use google properly.
Fox's Mercantile <jdangus@att.net>: Apr 21 09:42PM -0500

> 110 VAC went away at the beginning of the 20th century. By 1950
> 120 Volts was the standard. The MONIKER remained, but the voltage
> has been 120 VAC for a VERY long time.
 
We go through this over and over again on the antique radio news
group.
110, 117, 120 = 120 vac
 
 
--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com
bitrex <user@example.net>: Apr 21 11:11PM -0400

>> extend their life.
 
> The line voltage was already 120 Volts by then. You need a
> remedial electrical system / electronics industry history course.
 
But why when there are so many antiques available here to correct me
 
> Or maybe you would simply develop enough Internet skills to know
> how to use google properly.
 
Maybe you are so cranky all the time because yous are really easy to
manipulate into working for free.
bitrex <user@example.net>: Apr 21 11:28PM -0400

On 4/21/2021 10:42 PM, Fox's Mercantile wrote:
 
> We go through this over and over again on the antique radio news
> group.
> 110, 117, 120 = 120 vac
 
I'm hearing that DLUNU would like to take responsibility for this
project and I think he's the best qualified based on his rebuttal. I
mean it's in his name. "NumeroUno"
DecadentLinuxUserNumeroUno@decadence.org: Apr 22 03:29AM


> I'm hearing that DLUNU would like to take responsibility for this
> project and I think he's the best qualified based on his rebuttal. I
> mean it's in his name. "NumeroUno"
 
In case you missed it, he was backing me up.
bitrex <user@example.net>: Apr 21 11:43PM -0400

>> project and I think he's the best qualified based on his rebuttal. I
>> mean it's in his name. "NumeroUno"
 
> In case you missed it, he was backing me up.
 
I would hope so! You're team lead, now
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Digest for sci.electronics.repair@googlegroups.com - 8 updates in 3 topics

9:40 AM Penedão 0 comments
bob prohaska <bp@www.zefox.net>: Apr 21 01:05AM

From time to time it'd be really handy to have an oscilloscope. Something
like a Tektronix TDS2010 would be very nice. Too nice, and expensive,
for as often as I'd use it. And, much too good for the sorts of things
I'm likely to measure. An example would be watching for power supply
sags during computer boot-up, or maybe disk spin-up. Basically audio
bandwidth, but with the ability to capture transients by stop trigger.
 
What about "oscilloscopes" based on USB sound cards? The one that's
handy is xoscope, available via apt on RasPiOS. It's installed, but
the man page gives no hint what sort of sound device, or general purpose
A/D converters, are supported.
 
I don't have a hard-and-fast performance requirement, nor one for price.
It'd need to work from below 60Hz upwards, and cost around $10/kHz or
less at higher bandwidths with a cap in the $200-500 range. DC response
would be nice but not essential, calibrated amplitudes aren't really
necessary but would be convenient. Possibly the biggest constraint is
that I do not own a Windows license and have no modern Windows-compatible
hardware, so the choices are MacOS 10.7.5, RasPiOS or FreeBSD only.
 
If anybody has experiences or suggestions for devices and software to
consider please post.
 
Thanks for reading,
 
bob prohaska
Ralph Mowery <rmowery42@charter.net>: Apr 20 11:31PM -0400

In article <s5nton$nrq$1@dont-email.me>, bp@www.zefox.net says...
> less at higher bandwidths with a cap in the $200-500 range. DC response
> would be nice but not essential, calibrated amplitudes aren't really
> necessary but would be convenient. Possibly the biggest constraint is
 
If you are going to spend 200 to 500 look at the Hantek scopes for
around $ 350.
 
https://www.circuitspecialists.com/hantek-oscilloscope
Kerry Imming <kcimming@pobox.com>: Apr 21 07:22AM -0500

On 4/20/2021 8:05 PM, bob prohaska wrote:
> consider please post.
 
> Thanks for reading,
 
> bob prohaska
 
I have a Rigol DS1100 and have been very happy with it. The auto signal
find option makes it MUCH easier to use than the old scopes.
 
https://www.tequipment.net/Rigol/DS1102Z-E/Digital-Oscilloscopes/?b=y&v=7906
 
- Kerry
JJ Lark <cbr6850@nospamverizon.net>: Apr 20 01:00PM -0400

Worked out well. Ran the box fan at both medium and high speeds with
the filter across the front. I'm a little hesitant running the fan at
max for extended periods because it seems like the filter constricts the
input air flow. In any case, I did soldering, heat shrinking with
matches since my lighter ran out of fuel, and even marked some wires
with nail polish. No trouble at all. I expected the most lingering
smell would be the nail polish, but even that I could barely detect.
For $13 and the cheap box fan I already had, job well done!
Stephen Wolstenholme <steve@easynn.com>: Apr 21 12:53PM +0100

On Sun, 18 Apr 2021 10:07:59 -0400, JJ Lark
 
>https://www.walmart.com/ip/Filtrete-20x20x1-Allergen-Plus-Odor-Reduction-HVAC-Furnace-Air-Filter-1200-MPR-1-Filter/36728389
 
>Appealed to me since it already has built in charcoal filter as well.
>Won't be tested until this week. Thoughts?
 
When I was 16 I had a job in a TV factory. The PCBs were soldered by
floating them on solder baths. There was no sign of any smoke.
Soldering the components that had to be mounted by hand produced a
small amount gray smoke that was sucked up a vacuum pipe next to the
soldering iron. Almost everyone worked without the pipe because it got
in the way.
 
Steve
 
--
http://www.npsnn.com
Lucifer <LuciferMorningstar@bigpond.com>: Apr 21 09:41AM +1000

I have a Denon DMD-M10 minidisk recorder that will not play disks
recorded on other machines nor will it record on a disk that has been
used before. I was able to record on an unused disk which does play.
The OP is Lame <lame@lame.lame>: Apr 21 01:06AM

> I have a Denon DMD-M10 minidisk recorder that will not play disks
> recorded on other machines nor will it record on a disk that has been
> used before. I was able to record on an unused disk which does play.
 
And....?
 
Try asking a question next time.
dplatt@coop.radagast.org (Dave Platt): Apr 20 06:09PM -0700

In article <1kpu7ghcagbut46ti8sic77sjd9vuumodp@4ax.com>,
>I have a Denon DMD-M10 minidisk recorder that will not play disks
>recorded on other machines nor will it record on a disk that has been
>used before. I was able to record on an unused disk which does play.
 
At a guess, I'd suspect that it might be any of the typical faults
which can develop in any laser-optical-based disc recording and
playback system:
 
- Deteriorating laser (lower output level)
- Dirty laser or read-back optics (dust, tobacco or cannabis smoke
particles and tar)
- Dirty or poorly-lubricated "sled" on which the optical assembly moves
- Misadjusted servo tracking system
 
Power-supply problems e.g. deteriorating filter capacitors, loose
cables, intermittent contacts, etc. can also be a problem as these
devices age.
 
None of the above is at all specific to your recorder model. If
you're serious about trying to fix it, I'd suggest getting the
model-specific service manual (there's one up on eBay from a seller in
Florida - no connection).
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