Digest for sci.electronics.repair@googlegroups.com - 25 updates in 5 topics

Rheilly Phoull <rheilly@bigslong.com>: Aug 11 09:11AM +0800


> With that in mind, do it yourself, and report when you reach perfection.
 
> Peter Wieck
> Melrose Park, PA
 
Probably if he got out a bit more might help with such a momentous endeavor.
burfordTjustice <burfordTjustice@tues.uk>: Aug 11 08:12AM -0400

On Wed, 10 Aug 2016 09:33:46 -0700
 
> Here is a screenshot of the near-perfect desktop:
 
Only by your standard...
Aardvarks <aardvarks@a.b.c.com>: Aug 11 07:24AM -0700

On Thu, 11 Aug 2016 08:12:41 -0400, burfordTjustice wrote:
 
>> Here is a screenshot of the near-perfect desktop:
 
> Only by your standard...
 
Do you really think I'm the only one on the planet who organizes things by
the standard of "A place for everything & everything in its place"?
 
Really?
 
Only me?
 
What's your standard?
burfordTjustice <burfordTjustice@tues.uk>: Aug 11 10:37AM -0400

On Thu, 11 Aug 2016 07:24:05 -0700
 
> Really?
 
> Only me?
 
> What's your standard?
 
Do you think anyone really gives a rats ass
about your phone? How fucking big headed of you.
nospam <nospam@nospam.invalid>: Aug 11 10:40AM -0400

In article <noi1r0$1n64$1@gioia.aioe.org>, Aardvarks
 
> > Only by your standard...
 
> Do you really think I'm the only one on the planet who organizes things by
> the standard of "A place for everything & everything in its place"?
 
what you don't get is that everyone has a different notion of where to
put stuff.
 
there is no one single way to organize things.
Aardvarks <aardvarks@a.b.c.com>: Aug 11 08:16AM -0700

On Thu, 11 Aug 2016 10:37:40 -0400, burfordTjustice wrote:
 
> Do you think anyone really gives a rats ass
> about your phone? How fucking big headed of you.
 
I'm amazed that you actually think that I already thought of *every*
generally useful app that goes on the typical Android cellphone.
 
I was pretty sure that I must have been missing some apps, since I
generally pick only the best of the best free apps to do the jobs that I do
on a cellphone.
 
But I can't be the only one who has the brains to find the best apps for
the job, can I?
 
I mean, you don't have a *single* app on your phone that you find useful
for your purposes that I don't already have?
 
That you even imply that is amazing - because I'm not actually *that*
smart. Really.
 
I'm amazed that you can't offer a *single* improvement.
Not one?
 
I'm that good?
Aardvarks <aardvarks@a.b.c.com>: Aug 11 08:19AM -0700

On Thu, 11 Aug 2016 10:40:16 -0400, nospam wrote:
 
> what you don't get is that everyone has a different notion of where to
> put stuff.
 
Of course I get that notion.
That's exactly *why* I'm asking the two questions.
 
> there is no one single way to organize things.
 
I'm glad at least you *understand* that fundamental concept!
 
That's exactly why I asked the people here two fundamental questions.
 
1. How do *you* organize your desktop (screenshots would be useful)?
 
2. What apps do you find are the best freeware apps that I haven't thought
of yet?
 
The point is that I can't be the only one on this planet who has an
organized desktop containing only the best apps for Android.
 
Can I?
burfordTjustice <burfordTjustice@tues.uk>: Aug 11 11:20AM -0400

On Thu, 11 Aug 2016 08:16:50 -0700
> > about your phone? How fucking big headed of you.
 
> I'm amazed that you actually think that I already thought of *every*
> generally useful app that goes on the typical Android cellphone.
 
No one said that but you.
 
You avoided the question again:
 
Do you think anyone really gives a rats ass
about your phone? How fucking big headed of you.
Aardvarks <aardvarks@a.b.c.com>: Aug 11 08:23AM -0700

On Thu, 11 Aug 2016 07:58:19 -0700 (PDT), trader_4 wrote:
 
> It sure doesn't look anything like my phone, I'm very happy with
> how mine is organized, and would not want the organization A has,
> that's for sure.
 
There were two questions, where you can help me *improve* my Android setup.
 
1. How do *you* organize your phone?
a. What philosophy do you use?
b. What categories do you use?
c. Do you have a screenshot?
 
2. What apps do you find are *best*?
a. I only choose the best of the best free apps.
b. And I only choose them for what "I" do.
c. But I pretty much do what everyone else does.
 
I find it surprising if I really have found all the best free apps for each
purpose on a cellphone.
 
In fact, I'm sure I'm not that smart.
There's no way I have thought of everything.
 
Someone here must have either a category of apps that I entirely missed
that is generally useful, or, someone here must know of a great free app of
general use that I haven't tested and decided upon already.
 
So the two original and fundamental questions remain unanswered:
a. What organization category is missing from my desktop?
b. What best-of-the-best free app is missing from my phone?
"Gareth Magennis" <soundserviceleeds@outlook.com>: Aug 10 08:07PM +0100

I have a fairly vintage valve amplifier with a dead HT (standby) switch.
 
It's this kind of format, SPST rocker:
http://uk.farnell.com/arcolectric/c1500alaabb/switch-antibacterial-spst-black/dp/2068581
 
 
Now, this switches the rectified HT winding from the transformer, which is
around the usual 500v with no valves in place.
 
 
I've been looking at replacements, but have not found any such switch that
has a rating of 500v DC.
Here's a typical search result:
http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&categoryId=700000006219&eq=N%3D204319%2B110173704%2B2031%26amp%3BNtk%3Dnarrow_desc%26amp%3BNtt%3Drocker%2Bswitch%26amp%3BNtx%3Drel%2Bgensearch_store_specific%252cstatic%2528P_STORE_MARKETING_RANK_FARNELL_UK%252cascending%2529%2Bmode%2Bmatchall%26amp%3BNty%3D1%26amp%3BNtpc%3D1%26amp%3BNtpr%3D1%26amp%3BD%3Drocker%2Bswitch*%26amp%3BDn%3 D2031%2B2031%2B2031%26amp%3BDx%3Dmode%2Bmatchall&st=rocker%20switch&pageSize=25&showResults=true&aa=true&pf=110125431,110173704&vw=
 
 
Many of these seem to be only rated,or at least tested, at 24v DC (?)
Nothing I have found has been anywhere near 500v.
 
 
And, here is a Carling switch typically found in Fenders, Mesa etc, to
switch the typical 500v HT.
http://www.hotroxuk.com/carling-spst-toggle-switch-sw110-63.html
It has a maximum DC voltage rating of 250v, way higher than anything else I
have managed to find, but definitely not 500v rated.
 
 
 
 
I'm particularly concerned that the switch originally fitted, and similar
generic types available from Farnell only seem to be rated to 24v DC.
No wonder it is faulty.
 
Unless I am missing something here.
 
 
 
 
Gareth.
N_Cook <diverse@tcp.co.uk>: Aug 10 08:14PM +0100

On 10/08/2016 20:07, Gareth Magennis wrote:
 
> Gareth.
 
Is it a problem with the make or break? any HV cap over the contacts?
Parallel up a DPST switch, perhaps NOS would be better
"Gareth Magennis" <soundserviceleeds@outlook.com>: Aug 10 08:26PM +0100

"N_Cook" wrote in message news:nofufa$il$1@dont-email.me...
 
On 10/08/2016 20:07, Gareth Magennis wrote:
 
> Gareth.
 
Is it a problem with the make or break? any HV cap over the contacts?
Parallel up a DPST switch, perhaps NOS would be better
 
 
 
 
 
 
 
This is a vintage(ish) amp that has snap-in rectangular Mains and standby
switches. The Mains DPDT double width, the Standby SPST, single width.
 
I don't really want to be drilling holes for another switch that isn't even
rated to 500v.
 
 
Gareth.
"pfjw@aol.com" <pfjw@aol.com>: Aug 10 01:17PM -0700

On Wednesday, August 10, 2016 at 3:07:10 PM UTC-4, Gareth Magennis wrote:
> http://www.hotroxuk.com/carling-spst-toggle-switch-sw110-63.html
> It has a maximum DC voltage rating of 250v, way higher than anything else I
> have managed to find, but definitely not 500v rated.
 
 
This gets you to 400VDC: http://76.12.210.115/pdf/s-toggle-sw-rocker-400v-dc.pdf
 
and then, if you use a relay, you do not risk arc-welding the switch:
 
http://www.vsholding.com/datasheets/7107%20D3F500D6.PDF
 
Hope it helps. Keep in mind that at higher voltages, arcing is the concern. But you knew that already or you would not be asking the question.
 
Peter Wieck
Melrose Park, PA
"Gareth Magennis" <soundserviceleeds@outlook.com>: Aug 10 10:15PM +0100

wrote in message
news:7bb703cc-6d67-468e-a261-9353a8788713@googlegroups.com...
 
On Wednesday, August 10, 2016 at 3:07:10 PM UTC-4, Gareth Magennis wrote:
> It has a maximum DC voltage rating of 250v, way higher than anything else
> I
> have managed to find, but definitely not 500v rated.
 
 
This gets you to 400VDC:
http://76.12.210.115/pdf/s-toggle-sw-rocker-400v-dc.pdf
 
and then, if you use a relay, you do not risk arc-welding the switch:
 
http://www.vsholding.com/datasheets/7107%20D3F500D6.PDF
 
Hope it helps. Keep in mind that at higher voltages, arcing is the concern.
But you knew that already or you would not be asking the question.
 
Peter Wieck
Melrose Park, PA
 
 
 
 
 
 
Interesting that the switch you linked to uses a magnet to steer the arc, as
used on some Speaker Relays.
 
I'm guessing that valve amp manufacturers have used underated HT switches
for decades now, in much the same way that they have often put way higher
voltages on pre-amp valves than they are designed to cope with. (Fender,
Mesa reverb drive circuits for instance).
 
So I guess I shouldn't be so shocked at this revelation.
 
 
 
Gareth.
whit3rd <whit3rd@gmail.com>: Aug 10 02:32PM -0700

On Wednesday, August 10, 2016 at 12:07:10 PM UTC-7, Gareth Magennis wrote:
 
> I'm particularly concerned that the switch originally fitted, and similar
> generic types available from Farnell only seem to be rated to 24v DC.
> No wonder it is faulty.
 
I'd be tempted to rewire the unit to activate a high-side PMOS power FET
switch. The plastic switch could bias it from any positive or negative
low voltage with a NPN level translator (emitter driven from low voltage
DC on the replacement switch). Depending on the current you're switching,
even an optoisolator might suffice.
Phil Allison <pallison49@gmail.com>: Aug 10 08:50PM -0700

Gareth Magennis wrote:
 
> I have a fairly vintage valve amplifier with a dead HT (standby) switch.
 
** Is the failure mechanical or are the contacts burned up ?
 
 
> It's this kind of format, SPST rocker:
> http://uk.farnell.com/arcolectric/c1500alaabb/switch-antibacterial-spst-black/dp/2068581
 
> Now, this switches the rectified HT winding from the transformer,
 
** Where is the switch connected - in the AC feed ?
 
 
> around the usual 500v with no valves in place.
 
> I've been looking at replacements, but have not found any such switch that
> has a rating of 500v DC.
 
** And you won't.
 
> generic types available from Farnell only seem to be rated to 24v DC.
> No wonder it is faulty.
 
> Unless I am missing something here.
 
** You have missed the fact that the breaking capacity of a switch depends on the current flowing at the time. That rocker switch will break 24V DC and 250V AC all day long as long as the current does not exceed 16 amps.
 
In the Standby position of a valve amp, it maybe has to break 0.4 amps at most - so the voltage rating goes way up and it can be expected to do the job fine.
 
Plus any 250VAC mains switch is insulated to way more than the nominal voltage to allow for spikes etc - so that is OK too.
 
The best idea is to have the switch in the transformer wiring, breaking the AC voltage rather than the DC after the rectifier. Marshall did this in most models, using a double pole rocker.
 
But Fender got it *horribly* wrong in a great many models - like the Bassman 100 - connecting the switch in the one spot it should never be.
 
http://www.thevintagesound.com/ffg/schem/bassman_100_schem.gif
 
Imagine the switch is operated when the amp is on and running at high volume - maybe because of a sudden acoustic feedback.
 
Momentarily, as the switch opens, OT is fed HT from the 20uF electro but now in SERIES with the filter choke as the main electros are disconnected. Audio frequency current flows in the choke and generates a very large AC voltage pulse - making the switch contacts arc and the same voltage also appears on the output valve plates.
 
I have measured this voltage at more than 3kV rms.
 
A similar thing happens when the HT fuse in a70s or 80s Marshall blows, since it is wired in the same place.
 
Explains a lot of arc burnt valves and octal sockets.
 
 
.... Phil
"Gareth Magennis" <soundserviceleeds@outlook.com>: Aug 11 08:40AM +0100

"Phil Allison" wrote in message
news:66d4080c-49ef-41a4-b28f-1d59c03fe004@googlegroups.com...
 
Gareth Magennis wrote:
 
> I have a fairly vintage valve amplifier with a dead HT (standby) switch.
 
** Is the failure mechanical or are the contacts burned up ?
 
 
> It's this kind of format, SPST rocker:
> http://uk.farnell.com/arcolectric/c1500alaabb/switch-antibacterial-spst-black/dp/2068581
 
> Now, this switches the rectified HT winding from the transformer,
 
** Where is the switch connected - in the AC feed ?
 
 
> around the usual 500v with no valves in place.
 
> I've been looking at replacements, but have not found any such switch that
> has a rating of 500v DC.
 
** And you won't.
 
> generic types available from Farnell only seem to be rated to 24v DC.
> No wonder it is faulty.
 
> Unless I am missing something here.
 
** You have missed the fact that the breaking capacity of a switch depends
on the current flowing at the time. That rocker switch will break 24V DC and
250V AC all day long as long as the current does not exceed 16 amps.
 
In the Standby position of a valve amp, it maybe has to break 0.4 amps at
most - so the voltage rating goes way up and it can be expected to do the
job fine.
 
Plus any 250VAC mains switch is insulated to way more than the nominal
voltage to allow for spikes etc - so that is OK too.
 
The best idea is to have the switch in the transformer wiring, breaking the
AC voltage rather than the DC after the rectifier. Marshall did this in most
models, using a double pole rocker.
 
But Fender got it *horribly* wrong in a great many models - like the Bassman
100 - connecting the switch in the one spot it should never be.
 
http://www.thevintagesound.com/ffg/schem/bassman_100_schem.gif
 
Imagine the switch is operated when the amp is on and running at high
volume - maybe because of a sudden acoustic feedback.
 
Momentarily, as the switch opens, OT is fed HT from the 20uF electro but now
in SERIES with the filter choke as the main electros are disconnected. Audio
frequency current flows in the choke and generates a very large AC voltage
pulse - making the switch contacts arc and the same voltage also appears on
the output valve plates.
 
I have measured this voltage at more than 3kV rms.
 
A similar thing happens when the HT fuse in a70s or 80s Marshall blows,
since it is wired in the same place.
 
Explains a lot of arc burnt valves and octal sockets.
 
 
.... Phil
 
 
 
 
 
 
 
Thanks, Phil, that makes a little more sense now.
This switch is connected to the main filter caps, as in the Bassman
schematic, though I don't think it has a choke, it's a pretty sparse 50W
EL34 design (Roost, made in UK).
One Mullard EL34 is toast, the other is OK. It also had a shorted cap in
the tone stack totally crippling the whole amp.
 
I haven't yet managed to get the switch out of the chassis, it's a tight
bastard, was going to see if I could repair the contacts, but to do so it
needs to come out intact, or I need to source a replacement.
 
 
 
Cheers,
 
 
Gareth.
Phil Allison <pallison49@gmail.com>: Aug 11 01:50AM -0700

Gareth Magennis wrote:
 
> schematic, though I don't think it has a choke, it's a pretty sparse 50W
> EL34 design (Roost, made in UK).
> One Mullard EL34 is toast, the other is OK.
 
** The bad EL34 may be responsible for the burnt switch.
 
The owner may have tried to use the standby switch when the valve was passing a large DC current - like a couple of amps. At that level, a continuous arc would form and quickly destroy the contacts.
 
I see there is no DC choke in the schem but the fusing would allow that sort of current to flow.
 
http://www.andy-duke.co.uk/roost/Non_reverb_schematic_2006_05_14.png
 
Maybe when you replace the switch, rewire it in series with the HT fuse - that should allow arcs to extinguish at switch off.
 
 
.... Phil
Chris Jones <lugnut808@spam.yahoo.com>: Aug 11 11:22PM +1000

On 11/08/2016 18:50, Phil Allison wrote:
 
> http://www.andy-duke.co.uk/roost/Non_reverb_schematic_2006_05_14.png
 
> Maybe when you replace the switch, rewire it in series with the HT fuse - that should allow arcs to extinguish at switch off.
 
> .... Phil
 
Also, if you can get a 2-pole switch that fits ok, then wiring the two
sets of contacts in series ought to improve the ability to extinguish
the arc, (for a given contact separation etc.).
Phil Allison <pallison49@gmail.com>: Aug 11 06:54AM -0700

Chris Jones wrote:
 
> Also, if you can get a 2-pole switch that fits ok, then wiring the two
> sets of contacts in series ought to improve the ability to extinguish
> the arc, (for a given contact separation etc.).
 
** If you look at the schem, the HT fuse is in the rectifier ground path where the voltage and current levels drop to zero at twice the supply frequency.
 
So for a couple of mS each 10mS, there is not enough of either to sustain an arc.
 
 
... Phil
Chris Jones <lugnut808@spam.yahoo.com>: Aug 12 12:02AM +1000

On 11/08/2016 23:54, Phil Allison wrote:
>> the arc, (for a given contact separation etc.).
 
> ** If you look at the schem, the HT fuse is in the rectifier ground path where the voltage and current levels drop to zero at twice the supply frequency.
 
> So for a couple of mS each 10mS, there is not enough of either to sustain an arc.
 
Yes, I noticed that. It is much better than the original arrangement. If
C23 and C24 are in good condition and the B supply rail doesn't get
shorted, then the fuse (and new switch) should only be carrying current
for a quite small fraction of the time, so arcs should extinguish well,
perhaps even better than with a resistive load on AC.
Chuck <chuck@mydeja.net>: Aug 11 08:39AM -0500

On Tue, 9 Aug 2016 12:56:45 -0700, dplatt@coop.radagast.org (Dave
Platt) wrote:
 
 
>Tell the telco this, when you call: "I have confirmed that the
>problem remains when all customer-premises wiring and equipment is
>disconnected at the demarc."
 
Unfortunately, I live in OK.. Consumer protection here is
nonexistant. This state is controlled by corporate interests. A
fossil fuel billionare says it is commies that are against fracking
when peoples houses are being shaken apart by earthquakes.
 
---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
"pfjw@aol.com" <pfjw@aol.com>: Aug 11 05:03AM -0700

KUTZTOWN XXXV
September 16 & 17, 2016
 
http://www.dvhrc.com/docs/Upcomingshowinfo.pdf
 
Time to start planning now – Kutztown is very probably the largest vintage radio and electronic equipment show in the US, possibly the world. Hundreds of dealers, thousands of attendees from the US and abroad and more.
Pictures from the Spring show: http://hagstar.phanfare.com/14281203
 
And, as always, admission is free (with the exception of early buyers on Thursday, the 15th). Camping is free, table costs are reasonable – but if you reserve at this late date, you will be in the second pavilion if space is available at all, and each table has power.
You will find me at the club table running the diagnostic clinic, and teaching the basics of recapping and cleaning.
 
Peter Wieck
Melrose Park, PA
Stephen <f6ceedb9c75b52f7fcc0a55cf0cfbf5d_1045@example.com>: Aug 11 01:37AM

responding to
http://www.electrondepot.com/repair/my-sanyo-portable-model-vcr-7300-needs-the-loading-165907-.htm
, Stephen wrote:
 
> jurb, Adrian:
 
> Why you treating the guy that way? He sounds like he
> has a legitimate equipment problem.
 
--
Thank you "thekmanrocks" for your support.
 
I spent thousands of dollars on these 2 Beta HiFi VCRs in the early to mid
1980's, as I mentioned in my posted question.
 
Back then, a US dollar was worth more than it is today.
 
I also purchased a Sony Model 5200 back then, which I gave to my wife's
girlfriend and husband because their unit failed too.
 
My current goal is transfer the multiple tapes of movies I have in my
possession in beta format into DVD, or Blue Ray disks, via my new PC Blue Ray
burner drive.
 
My intent was not to disrupt the delicate sensibilities of the people who use
this forum.
 
Just searching the WWW for any company who could assist me.
 
Thanks.
 
 
 
--
 
 
--
 
 
--
JW <none@dev.null>: Aug 11 05:04AM -0400

On Thu, 11 Aug 2016 01:37:02 +0000 Stephen
<f6ceedb9c75b52f7fcc0a55cf0cfbf5d_1045@example.com> wrote in Message id:
 
>My intent was not to disrupt the delicate sensibilities of the people who use
>this forum.
 
>Just searching the WWW for any company who could assist me.
 
One of them asked a perfectly good question, to which you still haven't
answered.
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