sci.electronics.repair@googlegroups.com

Today's topics:

* Looking For Usable Multimeter - Cheap - 9 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/e1a0542b17d8b08d?hl=en
* Electrolytics blow after 1 hr - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/22739e68af51f6a4?hl=en
* The Official Lady Veteran FAQ v0.94 - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/4ff3cd59bf12198f?hl=en
* Slightly odd output stage configuration. Thoughts ? - 7 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/2588a3ac4e8b297d?hl=en
* (http://www.24hours-online.com/)Paypal payment Discount Wholesale/Retail LV,
Paket,Rolex,Omega,RADO,Armani ,Hermes,GUCCI ,Chanel,D&G,Burberry etc BRAND
watches - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/0c0672de38602126?hl=en
* Yammy PA ... - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/62e115d012f56e15?hl=en
* OT: Video - The new iPad v2 LOL! - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/4bd0fa206be2ad1c?hl=en
* Washing machine motor won't start, bad triac ? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/96d2b3fb706b3e62?hl=en
* What is the story with the Panasonic SA-PT760? - 3 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/04c2d2a64bf410b9?hl=en

==============================================================================
TOPIC: Looking For Usable Multimeter - Cheap
http://groups.google.com/group/sci.electronics.repair/t/e1a0542b17d8b08d?hl=en
==============================================================================

== 1 of 9 ==
Date: Fri, Feb 25 2011 12:21 pm
From: "William Sommerwerck"

> A decent DVM won't have a bargraph to annoy you.

That must make my Fluke 87 indecent.

== 2 of 9 ==
Date: Fri, Feb 25 2011 2:10 pm
From: "Michael A. Terrell"

William Sommerwerck wrote:
>
> > A decent DVM won't have a bargraph to annoy you.
>
> That must make my Fluke 87 indecent.

I prefer a good bench meter, and always found meters with bargraphs
to be very annoying. They don't have enough resolution for the work I
need a DVM for. For some jobs I've had to use a 5&3/4 digit DVM.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 3 of 9 ==
Date: Fri, Feb 25 2011 2:33 pm
From: Jeffrey Angus

On 2/25/2011 4:10 PM, Michael A. Terrell wrote:
> I prefer a good bench meter, and always found meters with bargraphs
> to be very annoying. They don't have enough resolution for the work I
> need a DVM for. For some jobs I've had to use a 5&3/4 digit DVM.

For a simple "Is it more or less?" Nothing beats a DC
coupled scope. If you're tuning for a maximum (or
minimum) you can easily see that out of the corner of
your eye with out having to take your eyes off your
fingers or the end of the tool you're adjusting things
with.

Jeff

== 4 of 9 ==
Date: Fri, Feb 25 2011 3:53 pm
From: "William Sommerwerck"

>>> A decent DVM won't have a bargraph to annoy you.

>> That must make my Fluke 87 indecent.

> I prefer a good bench meter, and always found meters with
> bargraphs to be very annoying. They don't have enough
> resolution for the work I need a DVM for. For some jobs I've
> had to use a 5&3/4 digit DVM.

If you're working at a bench, it makes sense to use a meter that sits at eye
level, rather than having to fiddle with what is basically a hand-held meter
(such as my 87).

Ad for the bar graph... I don't notice it unless I have a need for it.

== 5 of 9 ==
Date: Fri, Feb 25 2011 4:13 pm
From: "Dave Plowman (News)"

In article <ipCdnVVbGqQnmvXQnZ2dnUVZ_hudnZ2d@earthlink.com>,
Michael A. Terrell <mike.terrell@earthlink.net> wrote:
> > > I agree. I use mine all the time, but the contacts inside
> > > are wearing out. Where would you find an inexpensive new
> > > analog meter? Do they even make them anymore?
> >
> > A half decent DVM will have a a bargraph to mimic a needle movement.

> A decent DVM won't have a bargraph to annoy you.

It's there to inform. Of course information may well annoy you. And I
consider my Fluke quite decent.

--
*I want it all and I want it delivered

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

== 6 of 9 ==
Date: Fri, Feb 25 2011 7:19 pm
From: "Michael A. Terrell"

Jeffrey Angus wrote:
>
> On 2/25/2011 4:10 PM, Michael A. Terrell wrote:
> > I prefer a good bench meter, and always found meters with bargraphs
> > to be very annoying. They don't have enough resolution for the work I
> > need a DVM for. For some jobs I've had to use a 5&3/4 digit DVM.
>
> For a simple "Is it more or less?" Nothing beats a DC
> coupled scope. If you're tuning for a maximum (or
> minimum) you can easily see that out of the corner of
> your eye with out having to take your eyes off your
> fingers or the end of the tool you're adjusting things
> with.

As long as you don't have to set something to an exact value. Too
many years in TV Broadcast & Aerospace where you had to be able to set
something to less than a 1 mV error at 15 V. :(

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 7 of 9 ==
Date: Fri, Feb 25 2011 7:21 pm
From: "Michael A. Terrell"

"Dave Plowman (News)" wrote:
>
> In article <ipCdnVVbGqQnmvXQnZ2dnUVZ_hudnZ2d@earthlink.com>,
> Michael A. Terrell <mike.terrell@earthlink.net> wrote:
> > > > I agree. I use mine all the time, but the contacts inside
> > > > are wearing out. Where would you find an inexpensive new
> > > > analog meter? Do they even make them anymore?
> > >
> > > A half decent DVM will have a a bargraph to mimic a needle movement.
>
> > A decent DVM won't have a bargraph to annoy you.
>
> It's there to inform. Of course information may well annoy you. And I
> consider my Fluke quite decent.

When you're at a bench with over 30 pieces of test equipment,
including four or more identical DVMs the bargraph is just more visual
noise.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

== 8 of 9 ==
Date: Fri, Feb 25 2011 7:26 pm
From: Jeffrey Angus

On 2/25/2011 9:19 PM, Michael A. Terrell wrote:
>
> Jeffrey Angus wrote:
>>
>> On 2/25/2011 4:10 PM, Michael A. Terrell wrote:
>>> I prefer a good bench meter, and always found meters with bargraphs
>>> to be very annoying. They don't have enough resolution for the work I
>>> need a DVM for. For some jobs I've had to use a 5&3/4 digit DVM.
>>
>> For a simple "Is it more or less?" Nothing beats a DC
>> coupled scope. If you're tuning for a maximum (or
>> minimum) you can easily see that out of the corner of
>> your eye with out having to take your eyes off your
>> fingers or the end of the tool you're adjusting things
>> with.
>
>
> As long as you don't have to set something to an exact value. Too
> many years in TV Broadcast& Aerospace where you had to be able to set
> something to less than a 1 mV error at 15 V. :(
>
>

Well, that's what the FLuke bench DMMs are for. ;-)

Jeff

== 9 of 9 ==
Date: Fri, Feb 25 2011 7:49 pm
From: "Michael A. Terrell"

Jeffrey Angus wrote:
>
> On 2/25/2011 9:19 PM, Michael A. Terrell wrote:
> >
> > Jeffrey Angus wrote:
> >>
> >> On 2/25/2011 4:10 PM, Michael A. Terrell wrote:
> >>> I prefer a good bench meter, and always found meters with bargraphs
> >>> to be very annoying. They don't have enough resolution for the work I
> >>> need a DVM for. For some jobs I've had to use a 5&3/4 digit DVM.
> >>
> >> For a simple "Is it more or less?" Nothing beats a DC
> >> coupled scope. If you're tuning for a maximum (or
> >> minimum) you can easily see that out of the corner of
> >> your eye with out having to take your eyes off your
> >> fingers or the end of the tool you're adjusting things
> >> with.
> >
> >
> > As long as you don't have to set something to an exact value. Too
> > many years in TV Broadcast& Aerospace where you had to be able to set
> > something to less than a 1 mV error at 15 V. :(
> >
> >
>
> Well, that's what the Fluke bench DMMs are for. ;-)

Actually some were HP 5+3/4 digit with IEEE-488 interface to verify
calibration.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

==============================================================================
TOPIC: Electrolytics blow after 1 hr
http://groups.google.com/group/sci.electronics.repair/t/22739e68af51f6a4?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Feb 25 2011 12:58 pm
From: Baron

Meat Plow Inscribed thus:

> I once was trying to remove a photographer's external slave flash
> powerpack from it's case using two hemostats. I happened to clamp on
> the plus and minus output. I think it was 900 volts dc and had several
> large electrolytics about 3/4 the size of a soda can. Residual voltage
> caused my arms to fly outward and I stabbed a friend in the shoulder
> with one pair or the hemostats.
>
>
Ouch !

--
Best Regards:
Baron.

==============================================================================
TOPIC: The Official Lady Veteran FAQ v0.94
http://groups.google.com/group/sci.electronics.repair/t/4ff3cd59bf12198f?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Feb 25 2011 7:08 am
From: Michael Gross

1. What is Lady Veteran's real name?
2. What does Lady Veteran look like?
3. Are Lady Veteran's teeth really that brown?
4. Lady Veteran will claim that picture was altered. What say you?
5. Did Lady Veteran have her car repossed?
6. Is Lady Veteran really a serial beggar?
7. Does Lady Veteran use pay day loans?
8. What is Lady Veteran's height and weight?
9. What is Lady Veteran built like?
10. Is Lady Veteran a lesbian?
11. Does Lady Veteran have her own newsgroups?
12. Does Lady Veteran really live in a cheap, extended stay motel?
13. Does Lady Veteran take things to real life with people who disagree
with her?
14. Was Lady Veteran turned down recently to foster chihauhaus?
15. Is Lady Veteran so broke that she could not fix her computer for over 3
months when it crashed?
16. Is Lady Veteran really diseased?
17. Why was Lady Veteran kicked out of the Army?
18. Is Lady Veteran a racist?
19. What does Lady Veteran think of Air Force pilots?
20. Is Lady Veteran, despite being a lesbian, homophobic?
21. Lady Veteran is a net loon. Is she also insane in real life?
22. Was Lady Veteran forging Jean C?
23. Where does Lady Veteran work?
24. How can I get in contact with Lady Veteran?

1. What is Lady Veteran's real name?

Bobbi Sanchez

2. What does Lady Veteran look like?

http://fatreality.netfirms.com/blobbi.htm

3. Are Lady Veteran's teeth really that brown?

Yes.

4. Lady Veteran will claim that picture was altered. What say you?

LV will claim that the picture was altered, but only the name tag was
added. LV used to have the original picture posted on her personal web
site at http://profiles.yahoo.com/lady_veteran . It was taken down after a
dentist was shocked by the color of her teeth (Message-ID:
<43ms20p62nc280ro3q88en4h3vugdafg3l@4ax.com> ). LV subsequently replaced
the picture to avoid further embarrassment.

5. Did Lady Veteran have her car repossed?

Yes. Message-ID:
<38C814E536AE9844.15B8C70F1948AFC3.F2AA7341D7E8B72 1@lp.airnews.net>#1/1

6. Is Lady Veteran really a serial beggar?

Yes. Not only did she beg a priest for money to pay her rent (Message-ID:
<33FBD47F044F1402.9414A74F8938BCC8.AA82604960F75E4 2@lp.airnews.net>#1/1),
she also posted a message on NAAFA's web board and created a Geocities web
site for the sole purpose of begging for money for her war on trolls.

7. Does Lady Veteran use pay day loans?

Yes. Message-ID:
<AFDA5075017A206D.9F8B3834FF2B162D.2BCF533C1752740 2@lp.airnews.net>#1/1

8. What is Lady Veteran's height and weight?

5' 6 1/2", 240 pounds.

Message-ID: <em98lso2rg326hfelsrc10crvqjt1435dj@4ax.com>
Message-ID: <5utfctkamapne0sqh0v8c0gp3qhjon2i1g@4ax.com>

9. What is Lady Veteran built like?

Like a wrestler, according to LV herself.

Message-ID: <ubfbqs4r0koopeg7fa86or27b9mpcmf2db@4ax.com>

10. Is Lady Veteran a lesbian?

Apart from her unfeminine looks and Usenet behavior, LV admits to wearing
men's pants ( Message-ID:
<0spvlskkdg305qpeibhltspl04qv12ipsu@4ax.com>#1/1).

11. Does Lady Veteran have her own newsgroups?

Yes.

alt.blobbi.veteran-cunt
alt.fan.boar-semen.blobbi-sanchez
alt.fan.boar-semen.blobbi-sanchez.aka
alt.fan.boar-semen.blobbi-sanchez.aka.aka.lady-veteran

12. Does Lady Veteran really live in a cheap, extended stay motel?

Yes. Note her personal profile posted at
http://www.bestjobsus.com/bt-empd-armyvet.htm . This address is for the
Budget Suites of America.

13. Does Lady Veteran take things to real life with people who disagree
with her?

Yes. As financially distressed as she is, LV paid a private investigator
$500 to track down a 20 year old Canadian named Marty who was besting her
with their every encounter. LV later took things to real life with Jim
Dutton and contacted his employer. LV's mission is to take things to real
life with anyone who disagrees with her, assuming she can track the person
down.

14. Was Lady Veteran turned down recently to foster chihauhaus?

Yes, because her home was not a suitable environment according to the
rescue organization.

15. Is Lady Veteran so broke that she could not fix her computer for over 3
months when it crashed?

Yes. Message-ID: <010d01c265d6$9467ea00$18ea3040@MAIN>

16. Is Lady Veteran really diseased?

Yes. She suffers from lupus and boils. LV probably has some
co-morbidities associated with obesity as well.

17. Why was Lady Veteran kicked out of the Army?

Speculation surrounds her lesbianism.

18. Is Lady Veteran a racist?

Yes. Quoting from Message-ID: <svebc0h9nbj6955bsurqic2bhck2e05t4i@4ax.com>
:

The lower half of 1 black man is worth 10 complete white men. When
I fuck I like MEN, not little sissyboys that have to talk from
behind their mommy's skirt.

I lova da bothas:-)

<end quote>

Quoting from Message-ID:
<news:32593110AEB31ACC.AE57CF2C8A1A20A9.F0DCF962F6 552859@lp.airnews.net>

You talk about the Asian is very gifted. You should follow their
example by being polite,

AND QUIET!!!!!!!!!!

<end quote>

19. What does Lady Veteran think of Air Force pilots?

Lady Veteran is on the record stating that Air Force pilots are cowards.
Quoting from Message-ID:
<FD61BA67148006B8.0AC8A33AD0FC8798.555ED8B384D327D 0@lp.airnews.net>

They are most definitely cowards if they can't call a person fat to
their face and reap the benefits their comments so richly deserve.
BTW, I don't find hotshot pilots so brave. They fly up above the war
and could care less where their bombs fall. If they cared, maybe there
would be less war.

<end quote>

20. Is Lady Veteran, despite being a lesbian, homophobic?

Yes.

Quoting from Message-ID: <qu0571l8r39c8m1ib7a46dv63cai7hig6n@4ax.com>

Well when you get to the sigmoidoscopy just tell him that he is going
where no man has gone before...LOL!!

The idiots on this group sure can't say that.

<end quote>

21. Lady Veteran is a net loon. Is she also insane in real life?

Yes. In Lady Veteran's own words:

From: bbi@airmail.net (Bobbi Sanchez)
Subject: Jacque champion's Best Friend
Date: 1998/11/09
Message-ID:
<AA5737F4407BF438.75053B83A5011CDC.5BC343E27A26902 5@library-proxy.airnews.n
et>#1/1
Newsgroups: dfw.flame

I am trying to locate a lady named Terri who used to be a friend of
Jacque champion (mainden name Krippen). Both were involved in the
psychic community and Jacque is an experienced Tarot reader. She has
told people that Terri is languishing in some mental asylum and has
probably killed herself. I need to compare notes with Terri because
Jacque is saying the same thing about me.

<end quote>

22. Was Lady Veteran forging Jean C?

Yes. Proof was posted in Message-ID:
<2H8XKYQV38075.0543865741@Gilgamesh-Frog.org>

23. Where does Lady Veteran work?

The Empower Network
5055 Keller Springs
Suite 550
Addison, Texas 75001

Main--972-852-4100
Direct--972-852-4112
Fax--972-759-4405
http://www.theempowernetwork.com

24. How can I get in contact with Lady Veteran?

Home phone: 972-953-0771
Work phone: 972-852-4112
Mobile number: 214-995-8075

==============================================================================
TOPIC: Slightly odd output stage configuration. Thoughts ?
http://groups.google.com/group/sci.electronics.repair/t/2588a3ac4e8b297d?hl=en
==============================================================================

== 1 of 7 ==
Date: Fri, Feb 25 2011 4:12 pm
From: "Phil Allison"

"Arfa Daily"
>
>A muso customer has asked me to carry out some tonal mods to his Peavey
>Classic 30. All pretty straightforward cap changes and so on. However, he
>also asked me to look into fitting a pentode / triode switch whilst I was
>at it. At first glance, this didn't look like a problem. The output stage
>is a fairly classic AB class using 4 x EL84 tubes as two paralleled pairs.
>Anodes of each pair commoned. Cathodes all commoned and decked. Grids of
>each pair commoned via individual 47k stoppers. But then, things get a
>little odd around the screen grids. One tube of each pair, has its screen
>grid fed by a 100 ohm 5 watt resistor off the "screen" supply rail, whilst
>the other of each pair, has its screen grid fed *direct* from the "screen"
>supply rail.
>
> I don't think I've seen this done before.

** Peavey have been doing that since their first 4 tube ( 6L6GC) models.

See Peavey Deuce from 1975:

http://www.el34world.com/charts/Schematics/files/peavey/peavy_deuce-b.pdf

Strangely, the 6 tube models have 6 screen resistors.

http://www.el34world.com/charts/Schematics/files/peavey/Peavey_Mace_Deuce.pdf

> I doubt that it would have a significant effect on the operation of the
> stage, but just interested as to whether anyone else has come across this
> configuration, and knows the design reasoning behind it.

** Same question has puzzled me for ages - I suspect it could be an error
that has just got repeated over the decades. No-one but Peavey knows for
sure.

>Anyone got any opinions about just strapping the screens to the anodes on
>each pair via a switch, to implement a triode mode ?

** It better be a damn good switch, insulation and voltage rating wise -
most makers who have such triode/pentode switching use a very hefty slide
switch.

Also, the power output will of course drop in triode mode and each EL84 will
dissipate more heat under overdrive. Combined with their use of a
"concertina" phase splitter, I suspect that overdrive clipping will not be
symmetrical.

Not recommended.

.... Phil

== 2 of 7 ==
Date: Fri, Feb 25 2011 6:19 pm
From: "Arfa Daily"

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:8squrgFdptU1@mid.individual.net...
>
> "Arfa Daily"
>>
>>A muso customer has asked me to carry out some tonal mods to his Peavey
>>Classic 30. All pretty straightforward cap changes and so on. However, he
>>also asked me to look into fitting a pentode / triode switch whilst I was
>>at it. At first glance, this didn't look like a problem. The output stage
>>is a fairly classic AB class using 4 x EL84 tubes as two paralleled pairs.
>>Anodes of each pair commoned. Cathodes all commoned and decked. Grids of
>>each pair commoned via individual 47k stoppers. But then, things get a
>>little odd around the screen grids. One tube of each pair, has its screen
>>grid fed by a 100 ohm 5 watt resistor off the "screen" supply rail, whilst
>>the other of each pair, has its screen grid fed *direct* from the "screen"
>>supply rail.
>>
>> I don't think I've seen this done before.
>
> ** Peavey have been doing that since their first 4 tube ( 6L6GC) models.
>
> See Peavey Deuce from 1975:
>
> http://www.el34world.com/charts/Schematics/files/peavey/peavy_deuce-b.pdf
>
> Strangely, the 6 tube models have 6 screen resistors.
>
> http://www.el34world.com/charts/Schematics/files/peavey/Peavey_Mace_Deuce.pdf
>
>
>> I doubt that it would have a significant effect on the operation of the
>> stage, but just interested as to whether anyone else has come across this
>> configuration, and knows the design reasoning behind it.
>
> ** Same question has puzzled me for ages - I suspect it could be an error
> that has just got repeated over the decades. No-one but Peavey knows for
> sure.

Yes Phil. I too wondered whether it was an error. At first glance, I thought
that the two screen grids were commoned, and then taken back to a single
resistor, but when I looked at the print layout diagram a bit more
carefully, I could see that what appeared to be the case was that one screen
went to the 'cold' side of the resistor, and the other went to the 'hot'
side. A squint at the schematic then confirmed this ...

>
>>Anyone got any opinions about just strapping the screens to the anodes on
>>each pair via a switch, to implement a triode mode ?
>
> ** It better be a damn good switch, insulation and voltage rating wise -
> most makers who have such triode/pentode switching use a very hefty slide
> switch.

Yes indeed, my thoughts as well. Anode supply is quoted at 330v nominal, so
a switch rated to 250v ac, as most are, should be good for that. At the end
of the day, many tube amps use the same switch for the HT standby switching,
as they do for the mains, and lots of them run with an HT of much more than
330v.

>
> Also, the power output will of course drop in triode mode and each EL84
> will dissipate more heat under overdrive. Combined with their use of a
> "concertina" phase splitter, I suspect that overdrive clipping will not be
> symmetrical.

I hadn't considered that there might be any changes to the phase splitter
output as a result of such a change. What leads you to think that this might
be the case ?

>
> Not recommended.

Well, not something that I would normally recommend either, and the owner is
happy to live without the mod. He just thought that he would like to give it
a try if it was practical, whilst I was in there doing the other work.
Apparently, he would like to use it in 'triode' mode when he is at home
practicing. It's not actually a hard mod to carry out, and would be
reasonably easy to implement with the current print layout. I think what I
will probably do is to just 'hang' the mod in temporarily to see how it
performs, before doing any chassis drilling for switch fitting. If it seems
to work ok, then I'll finish it off. If not, I'll just recommend against it.
>
>
> .... Phil

Thanks for your comments Phil. Useful

Arfa

== 3 of 7 ==
Date: Fri, Feb 25 2011 6:25 pm
From: "Arfa Daily"

"Meat Plow" <mhywatt@yahoo.com> wrote in message
news:pan.2011.02.25.18.42.19@lmao.lol.lol...
> On Fri, 25 Feb 2011 17:00:41 +0000, Arfa Daily wrote:
>
>> A muso customer has asked me to carry out some tonal mods to his Peavey
>> Classic 30. All pretty straightforward cap changes and so on. However,
>> he also asked me to look into fitting a pentode / triode switch whilst I
>> was at it. At first glance, this didn't look like a problem. The output
>> stage is a fairly classic AB class using 4 x EL84 tubes as two
>> paralleled pairs. Anodes of each pair commoned. Cathodes all commoned
>> and decked. Grids of each pair commoned via individual 47k stoppers. But
>> then, things get a little odd around the screen grids. One tube of each
>> pair, has its screen grid fed by a 100 ohm 5 watt resistor off the
>> "screen" supply rail, whilst the other of each pair, has its screen grid
>> fed *direct* from the "screen" supply rail.
>>
>> I don't think I've seen this done before. I've seen one screen resistor
>> feeding both tubes of a pair, or one resistor per screen, but not just
>> one tube having a screen feed resistor. Apart from anything else, I
>> wouldn't normally have considered it very good design practice to have
>> no current limiting at all in place. Also, it will mean that the screen
>> voltage will be higher on one tube of the pair, than the other. I doubt
>> that it would have a significant effect on the operation of the stage,
>> but just interested as to whether anyone else has come across this
>> configuration, and knows the design reasoning behind it. Anyone got any
>> opinions about just strapping the screens to the anodes on each pair via
>> a switch, to implement a triode mode ?
>>
>> Arfa
>
> Several amp and tone stack mods. Variable cathode bias, OD mod on CH2, OT
> replacement, speaker replacement.
>
> blueguitar.org/new/articles/blue_gtr/amps/peavey/c30_origmod.pdf
>
>

Hi Meat. Yes, it is Blue Guitar mods that he wants to do. He is not
interested in the changes to the tone stack. He wants the output bias
changing from fixed grid to cathode auto, he wants the C4 cap value change
in the overdrive channel, and he wants the input simplification mod, where
all the C-R garbage between the I/P socket and the first 12AX7 grid is
removed, and a simple series resistor and grid return resistor are put in
their place, a la typical Fender and Marshall I/P schemes.

Arfa

== 4 of 7 ==
Date: Fri, Feb 25 2011 6:52 pm
From: "Phil Allison"

"Arfa Daily"
> "Phil Allison"
>>>Anyone got any opinions about just strapping the screens to the anodes on
>>>each pair via a switch, to implement a triode mode ?
>>
>> ** It better be a damn good switch, insulation and voltage rating wise -
>> most makers who have such triode/pentode switching use a very hefty slide
>> switch.
>
> Yes indeed, my thoughts as well. Anode supply is quoted at 330v nominal,
> so a switch rated to 250v ac, as most are, should be good for that.

** Nope.

Switches ( and relays) rated for AC operation are not suitable for DC
voltages above about 24 to 30 volts at the same current. DC arcs are tough
SOBs to break.

> At the end of the day, many tube amps use the same switch for the HT
> standby switching,

** All *sensible* designs switch the AC secondary of the transformer.
Those that switch the DC rail directly often arc and burn - even though
the current is generally only 100mA or so.

Fender ( for example ) did this in many older models, but chose a particular
switch that had a very large opening clearance to survive the inevitable
arcing - ESPECIALLY if the standby switch was ever operated under full
power.

Some Boogie models made the massive blunder of having the standby switch
parallel two electros ( one charged, one not) when it was closed. Splat.

>> Also, the power output will of course drop in triode mode and each EL84
>> will dissipate more heat under overdrive. Combined with their use of a
>> "concertina" phase splitter, I suspect that overdrive clipping will not
>> be symmetrical.
>
>
> I hadn't considered that there might be any changes to the phase splitter
> output as a result of such a change.

** Please try reading what is there.

The PS dos not itself change ( ??) but the job it has to do does - cos
the required grid drive to the EL84s is much higher in triode mode.
Concertina ( single triode ) PS circuits have less output and clip
asymmetrically compared to twin triode PS circuits.

>> Not recommended.
>
> Well, not something that I would normally recommend either, and the owner
> is happy to live without the mod. He just thought that he would like to
> give it a try if it was practical, whilst I was in there doing the other
> work. Apparently, he would like to use it in 'triode' mode when he is at
> home practicing.

** Wot a fuckwit.

It only drops the power by half or 3 dB.

.... Phil

== 5 of 7 ==
Date: Fri, Feb 25 2011 7:02 pm
From: "Phil Allison"

"Arfa Daily"

>> ** Same question has puzzled me for ages - I suspect it could be an error
>> that has just got repeated over the decades. No-one but Peavey knows for
>> sure.
>

** Here is my analysis:

The low value of 100 ohms in series with G2 has no significant effect on the
operation of a 6L6GC.

Peavey designs have a large value resistor ( 300 or 400 ohms 10W ) in the
feed to all G2s - unlike other amps that generally have a filter choke with
low DC resistance.

So, the 100 ohm resistors are there for factory test purposes only - so
staff can check if valves are drawing G2 currents within pre-determined
limits. G2 current levels mimic cathode currents for a given valve type and
brand.

By measuring the voltage drop across the 300 or 400 ohm resistor AND each
100 ohm in the G2 feeds - correct operation can be established.

Dunno about others - but I routinely check the voltage drop across each G2
resistor when servicing amps and replacing valves. It should be similar for
all valves in an output stage.

.... Phil

== 6 of 7 ==
Date: Fri, Feb 25 2011 7:42 pm
From: "Phil Allison"

"Arfa Daily"

> He wants the output bias changing from fixed grid to cathode auto,

** That will either lose you a lot of output power or cook that puny power
tranny ( by going close to class A operation) if you don't do it the smart
way.

Not recommended either.

..... Phil

== 7 of 7 ==
Date: Fri, Feb 25 2011 10:31 pm
From: David Nebenzahl

On 2/25/2011 4:12 PM Phil Allison spake thus:

> Also, the power output will of course drop in triode mode and each EL84 will
> dissipate more heat under overdrive. Combined with their use of a
> "concertina" phase splitter, I suspect that overdrive clipping will not be
> symmetrical.

If you wouldn't mind indulging my relative ignorance for a minute, that
"concertina" stage business got my curiosity up. So I found the two
triode (12AX7) stages before the EL84s, and it looks to me like the
first stage (V3A) is a phase inverter, with the other triode acting as
*another* phase inverter cascaded from the first stage, presumably with
unity gain. Is that correct?

So it seems this setup would be quite problem-prone, with possible phase
distortion and phase imbalance (or crossover distortion) effects. So why
would anyone use such a phase inverter, when there are much better ones
available?

--
The phrase "jump the shark" itself jumped the shark about a decade ago.

- Usenet

==============================================================================
TOPIC: (http://www.24hours-online.com/)Paypal payment Discount Wholesale/
Retail LV,Paket,Rolex,Omega,RADO,Armani ,Hermes,GUCCI ,Chanel,D&G,Burberry etc
BRAND watches
http://groups.google.com/group/sci.electronics.repair/t/0c0672de38602126?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Feb 25 2011 4:35 pm
From: POLO TSHIRT

(http://www.24hours-online.com/)Paypal payment Discount Wholesale/
Retail
LV,Paket,Rolex,Omega,RADO,Armani ,Hermes,GUCCI ,Chanel,D&G,Burberry
etc BRAND watches

==============================================================================
TOPIC: Yammy PA ...
http://groups.google.com/group/sci.electronics.repair/t/62e115d012f56e15?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Feb 25 2011 6:26 pm
From: "Arfa Daily"

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:ik8p8r$tp9$1@news.eternal-september.org...
> Arfa Daily <arfa.daily@ntlworld.com> wrote in message
> news:vYQ9p.81981$qA1.33262@newsfe08.ams2...
>>
>>
>> "N_Cook" <diverse@tcp.co.uk> wrote in message
>> news:ik7t80$o0s$1@news.eternal-september.org...
>> > Arfa Daily <arfa.daily@ntlworld.com> wrote in message
>> > news:2Jx9p.23650$Xm4.17829@newsfe10.ams2...
>> >> Anyone got schematics for a Yammy MS400 powered speaker ?
>> >>
>> >> TIA
>> >>
>> >> Arfa
>> >
>> > What does the R mean here? not rack-mount
>> > http://www.eserviceinfo.com/downloadsm/53690/Yamaha_MSR400.html
>> >
>> >
>>
>> Hmmm. Interesting. How did you find that on eserviceinfo ? I searched
> every
>> way I could think of, and never came up with that result. It does appear
> at
>> first glance, to be the correct manual for the unit, so thanks for that.
>> Just to make sure that I wasn't going mad or blind - well, mad already,
> and
>> getting more bat-like by the year :-) - I just went and checked again
> on
>> the actual unit, and it definitely says "Model MS400". No 'R' in there.
>>
>> Arfa
>>
>
> Their search is organised as OR to maximise ad revenue
> use instead Google implied-AND instead
>
> term1 AND term2 site:eserviceinfo.com
> in searchbox
> so you can use YAMAHA AND 400
> YAMAHA AND MS etc, not practical with OR
>
>

Ah ! Good tip. Thanks !

Arfa

==============================================================================
TOPIC: OT: Video - The new iPad v2 LOL!
http://groups.google.com/group/sci.electronics.repair/t/4bd0fa206be2ad1c?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Feb 25 2011 6:47 pm
From: RoadRunner

http://www.craigboyce.com/w/2011/02/ipad-2/

==============================================================================
TOPIC: Washing machine motor won't start, bad triac ?
http://groups.google.com/group/sci.electronics.repair/t/96d2b3fb706b3e62?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Feb 25 2011 7:42 pm
From: Sylvia Else

On 24/02/2011 10:25 PM, Andre Majorel wrote:
> On 2011-02-16, kwamena banson<virginbanson@gmail.com> wrote:
>
>> To be very sure you disconect the motor and test it on the mains at a
>> reduced voltage.
>
> The BTB15-600C is hard to find but RS carry the BTB16-600C.
> Swapping in a new triac made no difference, though.
>
> So I tried exactly what you're suggesting : motor on a big 24 V
> transformer. If the rotor is a certain angle (or 180� from it),
> the motor doesn't start when power is applied.
>
> When you reverse the phase on the stator (for reverse), you
> still have a pair of diametrically opposed "dead spots" but
> they're at an angle from the original ones.
>

That doesn't really sound right. Reversing the stator winding current
should reverse the force on the rotor, not change a zero force into a
non-zero force or vice versa.

I'd have to wonder whether one of the rotor windings has failed
open-cicuit. I think that could even account for the sparks. The
magnetic field for a winding that is becoming disconnected by the brush
action has to collapse because the broken winding that's being connected
cannot maintain the field.

Sylvia.

==============================================================================
TOPIC: What is the story with the Panasonic SA-PT760?
http://groups.google.com/group/sci.electronics.repair/t/04c2d2a64bf410b9?hl=en
==============================================================================

== 1 of 3 ==
Date: Fri, Feb 25 2011 8:34 pm
From: myfathersson

"Most cases, if a fuse in the front end of a switcher has failed, it
will have done so spectacularly "

Thanks guys, that is what I figured. You are right, this isnt a job
for me!

== 2 of 3 ==
Date: Fri, Feb 25 2011 8:34 pm
From: myfathersson

"Most cases, if a fuse in the front end of a switcher has failed, it
will have done so spectacularly "

Thanks guys, that is what I figured. You are right, this isnt a job
for me!

== 3 of 3 ==
Date: Fri, Feb 25 2011 8:36 pm
From: myfathersson

"Most cases, if a fuse in the front end of a switcher has failed, it
will have done so spectacularly "

Thanks guys, that is what I figured. You are right, this isnt a job
for me!

==============================================================================

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