How and where do you guys find schematics that you need to get a job done?
I have made a post here and one in the other schematic Usenet newsgroup for
alt.binaries.schematics.electronic, plus a couple of web boards and have
come up with nothing.

So do you make a polite request in a Usenet newsgroup (Which one(s)? Or
post a request on a web board or forum, if so which ones, or do you just
give up and scrap the job or try to work without it. Many jobs can be done
without them but someimes you really have to have the service manual or at
the very least, the schematic diagram.

Right now I am doing a "Carver Creation" with that Carver "magnetic field
core" power supply; a Sunfire True Subwoofer Super Junior that has a blown
amplifier in it. Both F1 & F2, 4A 250V fuses are open and the output
transistors, Q7 2SC3181 & Q11 2SA1302 are shorted. I have cut these
transistors from the board and they are indeed shorted. The MOSFETS; Q10,
Q12, Q21, & Q24, IRF640, appear to be dead shorted between main terminals 2
& 3, the gate on terminal 1 averages about 160 ohms to the main terminals 2
&3. I have removed them from the board for further testing and found that
two of them were indeed shorted. The good news is that I have tested with
my Fluke meter some of the small SMD components near the output section and
can find nothing burned, shorted, or open. Everything else looks good but
for the two large output transistors, 2 of the TO220 MOSFETS, and 2 GMA 4 A
fuses.

I am afraid to try to fire this thing up when fixed because of that Carver
"magnetic field core" power supply, I cannot variac it up slow and watch
the current nor can I use a 100 watt light bulb in place of the main fuse.
It seems to be a matter of replace the for sure bad ****, check all around,
pray, keep fingers crossed, plug it in and watch for smoke.

Any ideas on how to get the schematic, service manual, or tips on working
on this small beast? I am between jobs so I cannot afford to just buy the
service manual, even if it were indeed available.

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"Ohmster"

How and where do you guys find schematics that you need to get a job done?


** You often have to use persistence and ingenuity to get them out of the
makers.

Looks like Carver / Sunfire are keeping theirs secret.


I am afraid to try to fire this thing up when fixed because of that Carver
"magnetic field core" power supply, I cannot variac it up slow and watch
the current nor can I use a 100 watt light bulb in place of the main fuse.


** Sure you can.

Just bridge out the T1 and T2 terminals on that triac in the AC supply.

The PSU then reverts to entirely conventional - but will produce full DC
rails with only 65% of nominal AC volts going in. Go any higher and the
tranny's magnetic core will saturate and blow the AC fuse.

Use a small fuse ( ie 1 or 2 amps) when playing about.



It seems to be a matter of replace the for sure bad ****, check all
around,
pray, keep fingers crossed, plug it in and watch for smoke.


** Recipe for disaster.



....... Phil

[posted and mailed]

"Phil Allison" wrote in
:


"Ohmster"

How and where do you guys find schematics that you need to get a job
done?


** You often have to use persistence and ingenuity to get them out of
the makers.

Looks like Carver / Sunfire are keeping theirs secret.

Hmm, yeah it does. I wrote them for just a teeny weenie copy of the amp
and PS circuit but no answer yet.

I am afraid to try to fire this thing up when fixed because of that
Carver "magnetic field core" power supply, I cannot variac it up slow
and watch the current nor can I use a 100 watt light bulb in place of
the main fuse.


** Sure you can.

The dickens you say. I attached a small piece of the Carver M-400 PSU or
you can see it he
http://www.ohmster.com/~ohmster/pict...rvermfapsu.gif

Using this diagram, you are saying to just "short the triac" with wire,
main terminal to main terminal, leave the gate alone. For sure this would
make WAY to much power and blow the thing up but you say to bring it up
slow with a variac and stay down around 50-65% of the AC line and monitor
the "rails" on the amp to see if it is stable, not dumping DC, and does
not draw excessive current? Hey that is brillient! Dam, I don't have a
variac but could probably put my hands on one for the testing. That
probably would work too.

I do love the light bulb instead of the main fuse but that is not going
to work here at all, I am pretty sure. Oh, and use a small fuse, yes yes,
that would be correct.


Just bridge out the T1 and T2 terminals on that triac in the AC
supply.

The PSU then reverts to entirely conventional - but will produce
full DC rails with only 65% of nominal AC volts going in. Go any
higher and the tranny's magnetic core will saturate and blow the AC
fuse.

Use a small fuse ( ie 1 or 2 amps) when playing about.



It seems to be a matter of replace the for sure bad ****, check all
around,
pray, keep fingers crossed, plug it in and watch for smoke.

I am pretty sure I found the bad ****, 2 GMA4A fuses, 1 2SA1302 and 1
2SC3181major output transistors (The big flat plastic ones) and two of
four IRF640 are shorted. Cannot find anything more than that bad.

I think I will pass on the smoke and disaster, the idea you've pointed
out just might work. Thanks!

** Recipe for disaster.



...... Phil




Cheers, Phil.

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"BobW" wrote in
:

I have always been able to find schematics that I need by using a search
engine. Here's one for you:

www.google.com

Bob

Thank you Miss LaTella.

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"Ohmster"
"Phil Allison"

I am afraid to try to fire this thing up when fixed because of that
Carver "magnetic field core" power supply, I cannot variac it up slow
and watch the current nor can I use a 100 watt light bulb in place of
the main fuse.


** Sure you can.

The dickens you say. I attached a small piece of the Carver M-400 PSU or
you can see it he
http://www.ohmster.com/~ohmster/pict...rvermfapsu.gif

Using this diagram, you are saying to just "short the triac" with wire,
main terminal to main terminal, leave the gate alone. For sure this would
make WAY to much power and blow the thing up but you say to bring it up
slow with a variac and stay down around 50-65% of the AC line and monitor
the "rails" on the amp to see if it is stable, not dumping DC, and does
not draw excessive current? Hey that is brillient! Dam, I don't have a
variac but could probably put my hands on one for the testing. That
probably would work too.


** Its the way I usually test all Carver " Mag Field" amps that have had
internal repairs done.

There is no regulation, so the DC rails sag badly when he amp is under drive
and load.

When all is OK - undo the link.


I do love the light bulb instead of the main fuse but that is not going
to work here at all, I am pretty sure.


** Use one if you like.

Or just monitor the AC current draw with a 3.5 digit AC meter - preferably
true rms type.



...... Phil

"Tim Williams Posturing ****head from the Sewer "

"Ohmster"

How and where do you guys find schematics that you need to get a job
done?

I write them...

We call it design.



** Vile piles of sociopathic, autistic **** like Tim Williams are a
pernicious social disease - leeches on the rest of society.

Just like any human disease, 100% eradication is the only way to go.

If you know Keith, or anyone vile puke like him.

Murder him.

Any way you like.




....... Phil

"Ohmster" wrote in message
...
How and where do you guys find schematics that you need to get a job
done?

I write them...

We call it design.

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms

In article ,
Ohmster wrote:
How and where do you guys find schematics that you need to get a job done?
....
So do you make a polite request in a Usenet newsgroup (Which one(s)?

Despite the conversations here, a.b.s.electronics is just an auxillary
group set up to support the other electronics newsgroups because they
aren't supposed to have binary postings (and they get filtered out at
many sites if they do),

Start in sci.electronics.repair and put the name and model number in
the Subject: line.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

"Tim Williams" wrote in news:iYkVi.11$v%4.7
@newsfe05.lga:

"Ohmster" wrote in message
...
How and where do you guys find schematics that you need to get a job
done?

I write them...

We call it design.

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms



Yeah that is real sweet if you can do that but I am afraid it does not help
me much. Good day.

--
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"Phil Allison" wrote in
:

Hey thanks for writing back Phil. You may not have a schematic but at
least you have experience with these particular kinds of amplifiers and
are willing to help out a fellow tech and that goes a long way by itself.
Thank you my friend. Having a friend with experience is sometimes better
than even having the schematic. (I did write to Sunfire tech and asked
for a pdf of the schematic but got no answer so far.)

I the bad parts I found we

Quantity
Part Number
Description

1
2SA1302
Audio Output Transistor

1
2SC3181
Audio Output Transistor

2
IRF640
MOSFET Power Device

2
GMA 4A 250V
GMA Size Fuse

All of these were on the amp board and I did not find any other for sure
bad parts. The trouble I am having is finding this triac. This is a
Sunfire, "True Subwoofer Super Junior" (Hell of a model number, huh?) and
when my friend Bob was measuring the DC on the two main caps, he was
telling me there was like 157 VDC on each of them. Impossible I say, only
Carver does stuff like that and then he showed me, silk screened on the
small power board "Designed By Bob Carver". "Ohhhhh", I said, it must be
one of those mag field amps.

I am probably going to have to put up some pictures of the amp and boards
for you to look at Phil because I really cannot find this triac and am
not sure where to look. This is a weird subwoofer for sure. The whole
thing is a 9" cube, has an 8" passive on one side, and an 8" driver on
the other side of the cube with double magnets that are so strong that if
you put screws in a strong plastic bag into the unit and then pull the
bag out, the screws will stay stuck on the speaker magnet and the bag
will rip. Pushing in the driver by hand is very tough, this is no "breath
easy" driver, that is for sure, this thing NEEDS tons of power to push
the driver.


The dickens you say. I attached a small piece of the Carver M-400 PSU
or you can see it he
http://www.ohmster.com/~ohmster/pict...rvermfapsu.gif

Using this diagram, you are saying to just "short the triac" with
wire, main terminal to main terminal, leave the gate alone. For sure
this would make WAY to much power and blow the thing up but you say
to bring it up slow with a variac and stay down around 50-65% of the
AC line and monitor the "rails" on the amp to see if it is stable,
not dumping DC, and does not draw excessive current? Hey that is
brilliant! Dam, I don't have a variac but could probably put my hands
on one for the testing. That probably would work too.


** Its the way I usually test all Carver " Mag Field" amps that have
had internal repairs done.

Well, finding this triac is getting to be a trying experience so far. It
would have to be a fairly good sized part, yes? At least a TO220 case or
larger. i Don't see anything like that on the power board but for an
L7812CV and an L7912CV which are just + & - 12 volt regulators and there
is a very small transformer on the power board. The house AC also goes
straight to two very large diodes (After being cleaned by a choke) and
then to the two 1,000uF 200V capacitors.

Ugh, I just broke down and called up Sunfire Tech and spoke to Shad. He
took my name and number and said that all Sunfire amps are fixed at the
factory. There are no service manuals or schematics available to anyone
in order to protect their intellectual property. This unit does not use a
triac and he had a name for it but I forget what it was. He was a decent
guy but could not release too much information about the amp. He said
there is a woman there that knows Bob Carver and she has been there for
decades and does ALL of the Sunfire amps so Shad did not know all of the
technical information about the amp in great detail. I told him about the
two main outputs blown and the two MOSFETS blown and said I did not find
anything else wrong and is it possible that this could be all that is
wrong with the amp? Again he was not sure, the woman who fixes them and
all that.

He gave me the standard "Flat rate to fix the product is $275, ship it
right off to us and we will get it done for you, etc.". I told him I went
this far and had to at least give it a try. He understood and has me
logged in case I want to send it in for repair.

So, there is no triac in this product, there is 151 VDC across each main
cap, there is 302 VDC across both main caps at the same time as measured
with a Fluke, and Sunfire will release no technical information about the
product for fear of losing "intellectual property". Ugh.


There is no regulation, so the DC rails sag badly when he amp is under
drive and load.

When all is OK - undo the link.


I do love the light bulb instead of the main fuse but that is not
going to work here at all, I am pretty sure.


** Use one if you like.

I probably will do this although I doubt it will save the amp or anything
if something is wrong. I don't think I can use a variac but will try it
anyway to see what happens.


Or just monitor the AC current draw with a 3.5 digit AC meter -
preferably true rms type.



..... Phil

Man, I was going to snap you a picture or two of the 9" cube cabinet
showing the two drivers (One passive) with my desk cam and when I got the
cube within 3 feet of the monitor, the entire monitor discolored so badly
from the super strong magnetic field of the driver magnets that I had to
take it away from the computer. Anyway, here is what I have in the way of
pictures of the boards:
http://www.ohmster.com/~ohmster/sunfire/

Anyway, this is what the product looks like:
http://www.sunfire.com/SuperJrPR.htm

I really don't know what to do about this now Phil, what would you
suggest? Check and check again for anything that is shorted or open,
visually inspect, and if all looks okay, replace the two IRF640 MOSFETS
(These are common MOSFET output devices in the Pioneer Elite receivers.)
and the two shorted output transistors, 2SA1302 & 2SC3181 and then what,
just plug it in and keep fingers crossed? Do you think it is worth trying
to use a variac or light bulb in place of the fuse?

This is a strange one, what do you think, Phil? I need your input. Thanks
buddy.

--
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Put "messageforohmster" in message body
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"Phil Allison" wrote in message
...

"Tim Williams Posturing ****head from the Sewer "

"Ohmster"

How and where do you guys find schematics that you need to get a job
done?

I write them...

We call it design.



** Vile piles of sociopathic, autistic **** like Tim Williams are a
pernicious social disease - leeches on the rest of society.

Just like any human disease, 100% eradication is the only way to go.

If you know Keith, or anyone vile puke like him.

Murder him.

Any way you like.




...... Phil

Skipped your meds again?!

"Ohmster"

This is a strange one, what do you think, Phil? I need your input. Thanks
buddy.


** Looks like that amp uses a SMPS ( switch mode power supply).

The whole thing is quite bizarre.

A powered sub woofer in a 9 inch cube - strewth !!

Let Sunfire do it, they have built that thing so it is fit for factory
service only.





........ Phil

"Phil Allison" wrote in
:


This is a strange one, what do you think, Phil? I need your input.
Thanks buddy.


** Looks like that amp uses a SMPS ( switch mode power supply).

The whole thing is quite bizarre.

A powered sub woofer in a 9 inch cube - strewth !!

Let Sunfire do it, they have built that thing so it is fit for factory
service only.





....... Phil


I will tell you what, the magnets in the driver has got to be the
strongest magnet I have ever seen, dude. It is so hard to press the
diaphragm in with your fingers that it would take massive force just to
move it. I put screws for the unit in a very strong freezer zip lock back
and when I pull the bag of screws out, the screws stay stuck to the
magnet, the bag rips, and I end up with an empty, ripped freezer zip lock
bag. When I put the 9" cube with the driver in it near my computer to
take a deskcam picture for you, my monitor turns green and purple when
the darned cube is over 3 feet away! Not just a little green and purple,
but the whole image is massively discolored because of the strength of
the magnets used in this speaker. Bob Carver did publish a white paper on
his super subwoofers here if you are bored and want to read a bit about
just how this stuff is supposed to work:
http://www.sunfire.com/pdf/Sunfire_S...Whitepaper.pdf

No, it is not an smps, they had a word for it but I forgot what the hell
they called it, oh yeah, the power supply circuit utilized in this amp to
make tons of power but only supply what the amp needs at the time is
called "A Tracking Downconverter Circuit". To me is sounds pretty much
like the same **** with the triac but they found a new way of doing it.

I did use my meter and found that the two big caps. 1,000uF @ 200V are in
series and go down to the amp board. There is no "transformer to speak of
other than a small one on the small power board. The big caps get line
voltage, rectified directly to them and might even use a voltage doubler
configuration to end up with the 302 VDC that I observed across both
caps. Full wave rectification on 120 VAC house current yields about 160
VDC or so. The small transformer has small diodes with +12 and -12 volt
regulators on the board. Small standby current to run the low level and
turn on circuits, no doubt.

It looks like the common connection between the two big caps is speaker
ground. I think that the IRF640 MOSFETS (Datasheets here):
http://www.alldatasheet.com/view.jsp?Searchword=IRF640

Are part of this Tracking Downconverter Circuit and when the two large
output bipolar transistors blew, 2SA1302 & 2SC3181, they took out two of
the MOSFETS with them. This is all speculation as I have no schematic
because Bob Carver wants to keep that circuit as intellectual property.

So the 6 parts I need; 2 GMA4A fuses, 2 IRF640 MOSFETS, and 2 bipolar
output transistors cost maybe $25 or less, I will recheck for anything
shorted, open, or burned, then put them in and hope for the best. If it
works, great. If it smokes, then I lose the job and it goes back to
Sunfire for repair at the flat rate of $275.

Any last minute tips, Phil? Just plug it in and keep fingers crossed? Try
the light bulb or variac? What do you think? Thanks for sticking with me
on this Phil, because I really had no idea of how to proceed or what to
do about this situation and even just talking to another knowledgeable
person is enough to help one make up one's mind.

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(Mark Zenier) wrote in
:

In article ,
Ohmster wrote:
How and where do you guys find schematics that you need to get a job
done?
...
So do you make a polite request in a Usenet newsgroup (Which one(s)?

Despite the conversations here, a.b.s.electronics is just an auxillary
group set up to support the other electronics newsgroups because they
aren't supposed to have binary postings (and they get filtered out at
many sites if they do),

Ahhh, that makes sense.

Start in sci.electronics.repair and put the name and model number in
the Subject: line.

Will do.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)



Thanks Mark.

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