sci.electronics.repair - 16 new messages in 6 topics - digest

sci.electronics.repair
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Today's topics:

* Orange Rocker 30, combo, 2006 - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/fdf96ce609e107d9?hl=en
* LG DVD-HDD LH7800 - no/intermittent video on inputs (E-E) - 1 messages, 1
author
http://groups.google.com/group/sci.electronics.repair/t/d4fc9f00b24406a9?hl=en
* Just occasionally, it all works out ... :-) - 6 messages, 5 authors
http://groups.google.com/group/sci.electronics.repair/t/8acb2e5bc4fbe49f?hl=en
* Rectifier wiring - 5 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/b087d99e9ce594b1?hl=en
* Nike Shox NZ OZ Fusions http://www.jialiuonline.com/FOOTWEAR-Nike%20Shox-343
- 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/8f2ce92319da30d0?hl=en
* Cheap Wholesale burberry real leather Handbags - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/22fa6bd9a4c75275?hl=en

==============================================================================
TOPIC: Orange Rocker 30, combo, 2006
http://groups.google.com/group/sci.electronics.repair/t/fdf96ce609e107d9?hl=en
==============================================================================

== 1 of 2 ==
Date: Tues, Jul 6 2010 3:36 pm
From: "Gareth Magennis"

>
>>> The ones that were originally well made are now so old they have strange
>>> faults most techs have never seen before - while the ones made more
>>> recently have designed in faults never seen before by anyone.
>>>
>>> A few examples.
>>>
>>> 1. Recent Marshall combo amps with fibreglass PCBs that become LEAKY
>>> when hot - output valve bias goes crazy and even the phase splitter
>>> stage goes way out of DC balance in normal operation because of leakage
>>> from anode tracks to grid tracks. There is simply no fix for this
>>> problem.
>>
>>
>> Care to give me a model for that behaviour ?
>
>
> ** Yep - the JCM2000: TSL100 combo series.
>
> Easy to find many stories about the same problem on usenet and web forums.
>
>

Yes, Marshal TSL 100. Sigh. I have had two of these with faulty
PCB's. They do indeed leak, and destroy the output tubes, as the bias
goes totally crazy.
I spent hours on the first one trying to establish what the fuck was going
on, as it made no sense whatsoever.

Eventually I phoned Marshall. They know about this problem and are unable
to fix it. You need to replace the PCB with an upgraded design.

Gareth.

== 2 of 2 ==
Date: Tues, Jul 6 2010 6:32 pm
From: "Phil Allison"

"Gareth Magennis"
> >
>>>> The ones that were originally well made are now so old they have
>>>> strange faults most techs have never seen before - while the ones
>>>> made more recently have designed in faults never seen before by anyone.
>>>>
>>>> A few examples.
>>>>
>>>> 1. Recent Marshall combo amps with fibreglass PCBs that become LEAKY
>>>> when hot - output valve bias goes crazy and even the phase splitter
>>>> stage goes way out of DC balance in normal operation because of leakage
>>>> from anode tracks to grid tracks. There is simply no fix for this
>>>> problem.
>>>
>>>
>>> Care to give me a model for that behaviour ?
>>
>>
>> ** Yep - the JCM2000: TSL100 combo series.
>>
>> Easy to find many stories about the same problem on usenet and web
>> forums.
>>
>>
>
> Yes, Marshal TSL 100. Sigh. I have had two of these with faulty
> PCB's. They do indeed leak, and destroy the output tubes, as the bias
> goes totally crazy.
> I spent hours on the first one trying to establish what the fuck was going
> on, as it made no sense whatsoever.
>
>
> Eventually I phoned Marshall. They know about this problem and are unable
> to fix it. You need to replace the PCB with an upgraded design.

** Hope the are willing to supply that for free ??

Whole PCBs going leaky is hardly an example of "normal wear and tear".

.... Phil

==============================================================================
TOPIC: LG DVD-HDD LH7800 - no/intermittent video on inputs (E-E)
http://groups.google.com/group/sci.electronics.repair/t/d4fc9f00b24406a9?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Jul 6 2010 4:47 pm
From: Franc Zabkar

On Tue, 6 Jul 2010 02:40:30 -0700 (PDT), b <reverend_rogers@yahoo.com>
put finger to keyboard and composed:

>sorrry, that model number should read 'RH 7800' not LH 7800!

Maybe one of these is similar ...
http://www.jordansmanuals.com/default.aspx?Brand=LG&Product=DVD-VCR

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

==============================================================================
TOPIC: Just occasionally, it all works out ... :-)
http://groups.google.com/group/sci.electronics.repair/t/8acb2e5bc4fbe49f?hl=en
==============================================================================

== 1 of 6 ==
Date: Tues, Jul 6 2010 5:03 pm
From: Franc Zabkar

On Tue, 6 Jul 2010 13:21:03 +0000 (UTC), Meat Plow <mhywatt@yahoo.com>
put finger to keyboard and composed:

>I once found a live rodent inside an old RCA radio/turntable console.

He supplies the motive force for the turntable. Kinda like the
Flintstones ...

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

== 2 of 6 ==
Date: Tues, Jul 6 2010 5:09 pm
From: "Dave"

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:uvg736p6ocumiaqer1f3e027cnkjqi6nhr@4ax.com...
> On Tue, 6 Jul 2010 13:21:03 +0000 (UTC), Meat Plow <mhywatt@yahoo.com>
> put finger to keyboard and composed:
>
>>I once found a live rodent inside an old RCA radio/turntable console.
>
> He supplies the motive force for the turntable. Kinda like the
> Flintstones ...
>
> - Franc Zabkar
> --
> Please remove one 'i' from my address when replying by email.

LOL. Aaah shit. Thank you. I needed that.

Dave

== 3 of 6 ==
Date: Tues, Jul 6 2010 5:59 pm
From: b

On 6 jul, 13:21, "N_Cook" <dive...@tcp.co.uk> wrote:

> My favourite was finding an insect cocoon built into the optics section of a
> Philips AZ1101 and a micro-facetted (fittingly the delicate tracery looked
> as though it was part of the optics) piece of insect wing precisely in-line
> of the optical path from the laser to the mirror system.

I had this exact thing earlier this year! I was working on an AIWA
system which would not read discs. was about to toss it aside when I
noticed some dirt near the laser . After carefully removing the lens
there was some kind of dead insect blocking the beam path - removed,
cleaned up, reassembled and worked fine!
why it chose precisely the most precision-made heart of the machine to
live in is beyond me...
-B

== 4 of 6 ==
Date: Tues, Jul 6 2010 7:02 pm
From: "William Sommerwerck"

> I had this exact thing earlier this year! I was working on
> an AIWA system which would not read discs. I was about
> to toss it aside when I noticed some dirt near the laser.
> After carefully removing the lens there was some kind of
> dead insect blocking the beam path -- removed, cleaned
> up, reassembled and worked fine! Why it chose precisely
> the most precision-made heart of the machine to live in
> is beyond me...

Good taste? The desire to live in an upscale community?

== 5 of 6 ==
Date: Tues, Jul 6 2010 10:35 pm
From: "Michael A. Terrell"

Meat Plow wrote:
>
> I once found a live rodent inside an old RCA radio/turntable console.

I've seen rodents elected to piblic office.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

== 6 of 6 ==
Date: Tues, Jul 6 2010 10:36 pm
From: "Michael A. Terrell"

David Nebenzahl wrote:
>
> On 7/6/2010 11:35 AM klem kedidelhopper spake thus:
>
> [note message TRIMMING]
>
> > My all time favorite was the peanut butter and bannana sandwich that
> > someone left in a VCR. (Problem: the tape wouldn't load)....I always
> > appreciated the snack. Lenny
>
> I guess that's going way beyond the concept of the "cup holder" to a
> "sandwich storage compartment", eh?

There was a credit card commercial about things they covered,
including some kid shoving a peanut butter & jelly sandwich into a VCR.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

==============================================================================
TOPIC: Rectifier wiring
http://groups.google.com/group/sci.electronics.repair/t/b087d99e9ce594b1?hl=en
==============================================================================

== 1 of 5 ==
Date: Tues, Jul 6 2010 5:06 pm
From: "DoN. Nichols"

On 2010-07-06, beecrofter <beecrofter@yahoo.com> wrote:
> A neat use for bridge rectifiers is to put in battery powered devices
> so that the battery can go in either way .

Presuming that the device can accept the loss of two diode
forward drops from the battery to the load. (About 1.4V at reasonable
current levels and with silicon diodes.) Some things are close enough
to their minimum voltage threshold so this would not work well.

If the battery and diode are followed by a regulator, you
probably are all right.

Enjoy,
DoN.

--
Email: <dnichols@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

== 2 of 5 ==
Date: Tues, Jul 6 2010 5:23 pm
From: "Karl Townsend"

"DoN. Nichols" <dnichols@d-and-d.com> wrote in message
news:slrni37h3q.4ds.dnichols@Katana.d-and-d.com...
> On 2010-07-06, beecrofter <beecrofter@yahoo.com> wrote:
>> A neat use for bridge rectifiers is to put in battery powered devices
>> so that the battery can go in either way .
>
> Presuming that the device can accept the loss of two diode
> forward drops from the battery to the load. (About 1.4V at reasonable
> current levels and with silicon diodes.) Some things are close enough
> to their minimum voltage threshold so this would not work well.
>
> If the battery and diode are followed by a regulator, you
> probably are all right.
>
> Enjoy,
> DoN.

I'm curious. I use a 2:1 transformer, bridge rectifier and caps to power 80
volt AMC drives. This comes out about 4 volts high but hasn't seemed to
cause trouble. For a cheap volt drop could you just run the DC out through a
couple more diodes on a bridge rectifier?

Karl

== 3 of 5 ==
Date: Tues, Jul 6 2010 6:00 pm
From: "William Sommerwerck"

> I'm curious. I use a 2:1 transformer, bridge rectifier and
> caps to power 80V AMC drives. This comes out about
> 4V high but hasn't seemed to cause trouble. For a cheap
> voltage drop could you just run the DC out through a couple
> more diodes on a bridge rectifier?

Yup. Each silicon diode gives 0.6V to 0.7V drop. Make sure the diode's
current rating is sufficient.

== 4 of 5 ==
Date: Tues, Jul 6 2010 9:41 pm
From: "DoN. Nichols"

On 2010-07-07, Karl Townsend <karltownsend.NOT@embarqmail.com> wrote:
>
> "DoN. Nichols" <dnichols@d-and-d.com> wrote in message
> news:slrni37h3q.4ds.dnichols@Katana.d-and-d.com...
>> On 2010-07-06, beecrofter <beecrofter@yahoo.com> wrote:
>>> A neat use for bridge rectifiers is to put in battery powered devices
>>> so that the battery can go in either way .
>>
>> Presuming that the device can accept the loss of two diode
>> forward drops from the battery to the load. (About 1.4V at reasonable
>> current levels and with silicon diodes.) Some things are close enough
>> to their minimum voltage threshold so this would not work well.
>>
>> If the battery and diode are followed by a regulator, you
>> probably are all right.
>>
>> Enjoy,
>> DoN.
>
> I'm curious. I use a 2:1 transformer, bridge rectifier and caps to power 80
> volt AMC drives. This comes out about 4 volts high but hasn't seemed to
> cause trouble. For a cheap volt drop could you just run the DC out through a
> couple more diodes on a bridge rectifier?

Yes -- but it might be cheaper to use individual diodes since
you would need several bridges to get 4V. Let's see -- somewhere
between 0.600 V and 0.700 V per diode, so 6.6 diode drops (3 + bridges)
and 5.7 diode drops (3 - bridges). I would put the extra diodes between
the output of the bridge and the first capacitor.

And that 4V high is pretty close to right on for 120 VAC input.
We start by dividing the 120 VAC by 2 for the transformer ratio, then
multiplying by the square root of 2 (1.414) and it comes out to 84.84 V
peak.

But any diode drop will soften the supply's stiffness somewhat,
because there is some variation in voltage drop with current. Not
nearly as much as with a resistor, but some.

Better is to add a small filament transformer in series with the
primary to adjust the voltage into the bridge to the right value. 80V /
1.414 requires 56.57 VAC into the bridge -- hmmm ... adjust for two
diode drops at 0.650 V per diode requires 57.87 VAC into the bridge, so
multiply by 2 for the transformer ratio and you get 115.75 VAC. If your
line voltage is really 120 VAC, you need to drop 4.24 VAC -- so a 6.3
VAC center tapped filament transformer would give you a choice of 3.15
VAC for half the winding, or 6.3 VAC for the full winding -- wired to
oppose the line voltage. The secondary of the filament transformer
needs to be rated to handle the worst case current into the main
transformer.

But really -- since line voltage varies with neighborhood load
-- or state wide load -- (and lots of air conditioning load where I am
today) you are as likely to get 115 VAC as 120 VAC -- and that would be
just about right for your transformer. Right now, a line voltage
monitor is telling me that I'm getting 115 VAC. It usually runs between
117 VAC and 120 VAC here.

So -- unless the drive says 80 V *MAX* -- don't sweat it. You
will be right on some of the time, and a bit high some of the time. But
your speed will be controlled by the output from the tach generator and
what the amplifier (drive) does with it, not the supply voltage, which
will simply set the limiting speed of the motor -- and it will almost
never actually run at that speed. Remember that the computer feeds an
analog voltage to the amplifier (drive) which tells it how fast to go,
and the amplifier compares that voltage to the voltage from the tach
generator to adjust what voltage goes to the motor's primary windings.
Your speed will be right as long as the amplifier (drive) does not break
down from the applied voltage. So -- look up what it can safely accept.
If it says that the absolute maximum voltage is 80 VDC -- then you want
to either lower the voltage a bit so at 120 VAC you will have no more
than 80V DC, or set up a regulator as part of the power supply to make
sure that the output voltage is never anything but 80 VDC. (This
requires the transformer to produce a bit more voltage so the regulator
can toss some away in the process of regulating -- say perhaps 100 VDC
before the regulator.

I hope that I haven't told you too much. :-)

Good Luck,
DoN.

--
Email: <dnichols@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

== 5 of 5 ==
Date: Tues, Jul 6 2010 10:50 pm
From: Winston

On 7/6/2010 10:26 AM, William Sommerwerck wrote:

(...)

> "Giving away" inventions is not necessarily a good thing. The patent system
> actually encourages invention by increasing the likelihood an inventor will
> profit from his ideas.

I'm sorry to inform you that you are in violation of
my rights to those thoughts.

My lawyer discovered that any practitioner in the
field *could* have easily originated those thoughts
before you did; they are insufficiently
novel.

Additionally, with further work, I believe
we will be able to uncover historical instances
of each of those thoughts occurring as 'prior art'.

You are to cease expression of those thoughts or any
thought that could be considered derivative of them.

Either of those thoughts are now available for license
from me for a single - use fee of US $5.00.

See how this really works? :)

--Winston

==============================================================================
TOPIC: Nike Shox NZ OZ Fusions http://www.jialiuonline.com/FOOTWEAR-Nike%20
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http://groups.google.com/group/sci.electronics.repair/t/8f2ce92319da30d0?hl=en
==============================================================================

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TOPIC: Cheap Wholesale burberry real leather Handbags
http://groups.google.com/group/sci.electronics.repair/t/22fa6bd9a4c75275?hl=en
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