Discussion:
Sewing Machine question... Possibly for Ron.
(too old to reply)
Kate XXXXXX
2008-12-19 08:18:09 UTC
Permalink
My Elna Lotus Stella Air Electronic has blown a capacitor or summat...
Anyone got a circuit diagram? Alan can fix it, but needs the diagram to
determine particular component deatils.
<hubby on the line>
One 0.047 uF capacitor is noticably bulged. Two resistors are singed,
one so badly that the colour code is unreadable. Active components
(diodes, power transistor) look OK so I am hopeful that replacing the
damaged passive bits will be enough. I suspect that the capacitor
failed first, I believe they are prone to breakdown with age.
The circuit diagram will tell me what values to dig out from my mouldy
old box of spare resistors and capacitors :-)
Photos of the board ar available for the terminally curious. The
engineering is **impressive** - four sprung contacts make the sole
connection between the end cover with the board, and the motor and
light connections.
<hubby off line>
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
robb
2008-12-19 12:21:15 UTC
Permalink
Post by Kate XXXXXX
My Elna Lotus Stella Air Electronic has blown a capacitor or
summat...
Post by Kate XXXXXX
Anyone got a circuit diagram? Alan can fix it, but needs the
diagram to
Post by Kate XXXXXX
determine particular component deatils.
or if a circuit diagram is not available ? (which would not be
surprising.... as i have yet to find a Pfaff circuit diagram) a
picture of a good circuit board (perhaps from a working machine)
may give you enough to work with.

if i owned an elna lotus stella i would send you a pic of the
circuit board but i do not.
Post by Kate XXXXXX
<hubby on the line>
One 0.047 uF capacitor is noticably bulged. Two resistors are singed,
one so badly that the colour code is unreadable. Active
components
Post by Kate XXXXXX
(diodes, power transistor) look OK so I am hopeful that
replacing the
Post by Kate XXXXXX
damaged passive bits will be enough. I suspect that the
capacitor
Post by Kate XXXXXX
failed first, I believe they are prone to breakdown with age.
unless you had some power surge or short that clearly explains
why the components failed...

i am guessing Mr. Alan knows most of this already ....

it has been my experience that passive components usually fail
because some active component has failed and allowed too much
voltage or current or spikes or frequency ( bla bla ) to pass
through the passive components so i would not discount those yet.

can style (electrolytic) caps can fail due to age (especially
the small cans) but mostly due to poor quality also if one has
failed on the board due to age or poor quality then i would
suspect many of the others as well. There are several incidents
of mother boards and some high tech test equipment that had cap
problems and the solution was to replace all the cheapo caps.

remember with caps to match polarity and that a higher voltage
cap of same capacitance can be used in the place of a lower
voltage cap of same capacitance if you have the space to fit it
in. (ie. voltage rating of new cap must be equall or higher than
old cap)
Post by Kate XXXXXX
The circuit diagram will tell me what values to dig out from
my mouldy
Post by Kate XXXXXX
old box of spare resistors and capacitors :-)
or photos of a good board.
Post by Kate XXXXXX
Photos of the board ar available for the terminally curious.
The
Post by Kate XXXXXX
engineering is **impressive** - four sprung contacts make the sole
connection between the end cover with the board, and the
motor and
Post by Kate XXXXXX
light connections.
<hubby off line>
where are the pictures ? i am terminally curious :)
Post by Kate XXXXXX
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
hth
robb
Kate XXXXXX
2008-12-19 12:48:21 UTC
Permalink
Post by Kate XXXXXX
Post by Kate XXXXXX
My Elna Lotus Stella Air Electronic has blown a capacitor or
summat...
Post by Kate XXXXXX
Anyone got a circuit diagram? Alan can fix it, but needs the
diagram to
Post by Kate XXXXXX
determine particular component deatils.
or if a circuit diagram is not available ? (which would not be
surprising.... as i have yet to find a Pfaff circuit diagram) a
picture of a good circuit board (perhaps from a working machine)
may give you enough to work with.
if i owned an elna lotus stella i would send you a pic of the
circuit board but i do not.
Post by Kate XXXXXX
<hubby on the line>
One 0.047 uF capacitor is noticably bulged. Two resistors are
singed,
Post by Kate XXXXXX
one so badly that the colour code is unreadable. Active
components
Post by Kate XXXXXX
(diodes, power transistor) look OK so I am hopeful that
replacing the
Post by Kate XXXXXX
damaged passive bits will be enough. I suspect that the
capacitor
Post by Kate XXXXXX
failed first, I believe they are prone to breakdown with age.
unless you had some power surge or short that clearly explains
why the components failed...
i am guessing Mr. Alan knows most of this already ....
it has been my experience that passive components usually fail
because some active component has failed and allowed too much
voltage or current or spikes or frequency ( bla bla ) to pass
through the passive components so i would not discount those yet.
can style (electrolytic) caps can fail due to age (especially
the small cans) but mostly due to poor quality also if one has
failed on the board due to age or poor quality then i would
suspect many of the others as well. There are several incidents
of mother boards and some high tech test equipment that had cap
problems and the solution was to replace all the cheapo caps.
remember with caps to match polarity and that a higher voltage
cap of same capacitance can be used in the place of a lower
voltage cap of same capacitance if you have the space to fit it
in. (ie. voltage rating of new cap must be equall or higher than
old cap)
He probably does... Old hardware engineer background. The repair and
service manual will probably have it, but I don't know anyone with a
copy, I don't think. Off to make a phone call...
Post by Kate XXXXXX
Post by Kate XXXXXX
The circuit diagram will tell me what values to dig out from
my mouldy
Post by Kate XXXXXX
old box of spare resistors and capacitors :-)
or photos of a good board.
They'd have to be VERY clear to show the colours and numbers on the
bits, but yes.
Post by Kate XXXXXX
Post by Kate XXXXXX
Photos of the board ar available for the terminally curious.
The
Post by Kate XXXXXX
engineering is **impressive** - four sprung contacts make the
sole
Post by Kate XXXXXX
connection between the end cover with the board, and the
motor and
Post by Kate XXXXXX
light connections.
<hubby off line>
where are the pictures ? i am terminally curious :)
I'll get them up.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
robb
2008-12-19 14:18:35 UTC
Permalink
Post by Kate XXXXXX
Post by Kate XXXXXX
Post by Kate XXXXXX
My Elna Lotus Stella Air Electronic has blown a capacitor or
summat...
Post by Kate XXXXXX
Anyone got a circuit diagram? Alan can fix it, but needs
the
Post by Kate XXXXXX
Post by Kate XXXXXX
diagram to
Post by Kate XXXXXX
determine particular component deatils.
[trim]
Post by Kate XXXXXX
He probably does... Old hardware engineer background. The
repair and
Post by Kate XXXXXX
service manual will probably have it, but I don't know anyone
with a
Post by Kate XXXXXX
copy, I don't think. Off to make a phone call...
I do hope your luck finding a circuit diagram (schematic) is
better than mine was.

I bought three different pfaff service manuals expecting/hoping
to find "schematic" info and no joy. One of the service manuals
appeared to have spent time on an actuall Pfaff service center
work bench.

I think many sewing machine companies really protect this info.

I ultimately purchased another working machine (a working circuit
diagram :)) just to repair the broken machine.

I was surprised to find that the elna service manuals are
available directly, i presume you already have links like these

http://www.elna.us/files/File/service_manuals/

http://www.elna.us/files/File/service_manuals/stella_service_manual.pdf

may have to add an elna to the collection just for kudos to elna
for providing such info.

robb
Kate XXXXXX
2008-12-19 17:15:10 UTC
Permalink
Post by robb
Post by Kate XXXXXX
Post by Kate XXXXXX
Post by Kate XXXXXX
My Elna Lotus Stella Air Electronic has blown a capacitor or
summat...
Post by Kate XXXXXX
Anyone got a circuit diagram? Alan can fix it, but needs
the
Post by Kate XXXXXX
Post by Kate XXXXXX
diagram to
Post by Kate XXXXXX
determine particular component deatils.
[trim]
Post by Kate XXXXXX
He probably does... Old hardware engineer background. The
repair and
Post by Kate XXXXXX
service manual will probably have it, but I don't know anyone
with a
Post by Kate XXXXXX
copy, I don't think. Off to make a phone call...
I do hope your luck finding a circuit diagram (schematic) is
better than mine was.
I bought three different pfaff service manuals expecting/hoping
to find "schematic" info and no joy. One of the service manuals
appeared to have spent time on an actuall Pfaff service center
work bench.
I think many sewing machine companies really protect this info.
I ultimately purchased another working machine (a working circuit
diagram :)) just to repair the broken machine.
I was surprised to find that the elna service manuals are
available directly, i presume you already have links like these
http://www.elna.us/files/File/service_manuals/
http://www.elna.us/files/File/service_manuals/stella_service_manual.pdf
may have to add an elna to the collection just for kudos to elna
for providing such info.
robb
A working Elna built in Switzerland rather than a sheep in wolf's
clothing, is a joy to use, and a beautiful bit of engineering. Do get
one if you can.

I have those url's bookmarked, but cannot get the pdf's to download. :(
My Adobe reader works perfectly well with other downloadable files (I
just downloaded a heap from the General Teaching Council here in the
UK), but, oddly, not with these.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
robb
2008-12-19 17:42:01 UTC
Permalink
Post by Kate XXXXXX
A working Elna built in Switzerland rather than a sheep in
wolf's
Post by Kate XXXXXX
clothing, is a joy to use, and a beautiful bit of engineering.
Do get
Post by Kate XXXXXX
one if you can.
I have those url's bookmarked, but cannot get the pdf's to
download. :(
Post by Kate XXXXXX
My Adobe reader works perfectly well with other downloadable
files (I
Post by Kate XXXXXX
just downloaded a heap from the General Teaching Council here
in the
Post by Kate XXXXXX
UK), but, oddly, not with these.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
I had a similar problem accessing those files after my first
access.

as luck would have it (not really ;) ) i'll send you what i
saved when i found the link
via your web page though it does not contain what you want.

enjoy
robb
Kate XXXXXX
2008-12-19 23:52:37 UTC
Permalink
Post by robb
I had a similar problem accessing those files after my first
access.
as luck would have it (not really ;) ) i'll send you what i
saved when i found the link
via your web page though it does not contain what you want.
enjoy
robb
Reply To will work. Thank you. :)
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
IMS
2008-12-19 19:19:14 UTC
Permalink
I seem to be able to download them just fine, if you let me know which
one you want I'll DL it and send it to you. -Irene

On Fri, 19 Dec 2008 17:15:10 +0000, Kate XXXXXX
Post by Kate XXXXXX
A working Elna built in Switzerland rather than a sheep in wolf's
clothing, is a joy to use, and a beautiful bit of engineering. Do get
one if you can.
I have those url's bookmarked, but cannot get the pdf's to download. :(
My Adobe reader works perfectly well with other downloadable files (I
just downloaded a heap from the General Teaching Council here in the
UK), but, oddly, not with these.
Lizzy Taylor
2008-12-19 12:23:32 UTC
Permalink
The circuit diagram will tell me what values to dig out from my mouldy
old box of spare resistors and capacitors :-)
Alan/Kate,

If you do not have the resistor values (once you find out what they are)
let me know and I'll see if we have them in any of our boxes of bits....

Lizzy
Kate XXXXXX
2008-12-19 12:34:22 UTC
Permalink
Post by Lizzy Taylor
The circuit diagram will tell me what values to dig out from my mouldy
old box of spare resistors and capacitors :-)
Alan/Kate,
If you do not have the resistor values (once you find out what they are)
let me know and I'll see if we have them in any of our boxes of bits....
Lizzy
Will do! Many thanks.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
Kay Lancaster
2008-12-19 22:42:05 UTC
Permalink
Ray White is the guy I'd think of as probably most likely to have the
values you need for that capacitor... just google Ray White and Elna together;
I think he goes by Elnaman.
Kate XXXXXX
2008-12-19 23:55:29 UTC
Permalink
Post by Kay Lancaster
Ray White is the guy I'd think of as probably most likely to have the
values you need for that capacitor... just google Ray White and Elna together;
I think he goes by Elnaman.
He does and I have him bookmarked. We may yet resort to that, though
himself is having fun reverse engineering the problem... ;)
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
Kay Lancaster
2008-12-20 10:42:03 UTC
Permalink
On Fri, 19 Dec 2008 23:55:29 +0000, Kate XXXXXX
Post by Kate XXXXXX
Post by Kay Lancaster
Ray White is the guy I'd think of as probably most likely to have the
values you need for that capacitor... just google Ray White and Elna together;
I think he goes by Elnaman.
He does and I have him bookmarked. We may yet resort to that, though
himself is having fun reverse engineering the problem... ;)
Yah, I've got one just like Alan... "dear, could you hold this probe right
here, and what did I do with the soldering station we used to build the..."

GAHH!

Kay
Pogonip
2008-12-20 21:52:12 UTC
Permalink
Post by Kay Lancaster
On Fri, 19 Dec 2008 23:55:29 +0000, Kate XXXXXX
Post by Kate XXXXXX
Post by Kay Lancaster
Ray White is the guy I'd think of as probably most likely to have the
values you need for that capacitor... just google Ray White and Elna together;
I think he goes by Elnaman.
He does and I have him bookmarked. We may yet resort to that, though
himself is having fun reverse engineering the problem... ;)
Yah, I've got one just like Alan... "dear, could you hold this probe right
here, and what did I do with the soldering station we used to build the..."
GAHH!
Kay
You *could* have one like mine -- who says a hammer has too many moving
parts and he can't find the battery compartment.
--
Joanne
stitches @ singerlady.reno.nv.us.earth.milky-way.com
http://members.tripod.com/~bernardschopen/
BEI Design
2008-12-20 22:28:49 UTC
Permalink
Post by Pogonip
Post by Kay Lancaster
On Fri, 19 Dec 2008 23:55:29 +0000, Kate XXXXXX
Post by Kate XXXXXX
Post by Kay Lancaster
Ray White is the guy I'd think of as probably most
likely to have the values you need for that
capacitor... just google
Ray White and Elna together; I think he goes by
Elnaman.
He does and I have him bookmarked. We may yet resort
to that, though himself is having fun reverse
engineering the
problem... ;)
Yah, I've got one just like Alan... "dear, could you
hold this probe right here, and what did I do with the
soldering station we
used to build the..." GAHH!
Kay
You *could* have one like mine -- who says a hammer has
too many moving parts and he can't find the battery
compartment.
If forced to choose between the two, I will take Kay's and
Kate's every time!

Beverly
Pogonip
2008-12-20 22:41:21 UTC
Permalink
Post by BEI Design
Post by Pogonip
Post by Kay Lancaster
On Fri, 19 Dec 2008 23:55:29 +0000, Kate XXXXXX
Post by Kate XXXXXX
Post by Kay Lancaster
Ray White is the guy I'd think of as probably most
likely to have the values you need for that
capacitor... just google
Ray White and Elna together; I think he goes by
Elnaman.
He does and I have him bookmarked. We may yet resort
to that, though himself is having fun reverse
engineering the
problem... ;)
Yah, I've got one just like Alan... "dear, could you
hold this probe right here, and what did I do with the
soldering station we
used to build the..." GAHH!
Kay
You *could* have one like mine -- who says a hammer has
too many moving parts and he can't find the battery
compartment.
If forced to choose between the two, I will take Kay's and
Kate's every time!
Beverly
He has other redeeming qualities. I think......
--
Joanne
stitches @ singerlady.reno.nv.us.earth.milky-way.com
http://members.tripod.com/~bernardschopen/
Ron Anderson
2008-12-19 13:52:15 UTC
Permalink
Post by Kate XXXXXX
My Elna Lotus Stella Air Electronic has blown a capacitor or summat...
Anyone got a circuit diagram? Alan can fix it, but needs the diagram to
determine particular component deatils.
<hubby on the line>
One 0.047 uF capacitor is noticably bulged. Two resistors are singed,
one so badly that the colour code is unreadable. Active components
(diodes, power transistor) look OK so I am hopeful that replacing the
damaged passive bits will be enough. I suspect that the capacitor
failed first, I believe they are prone to breakdown with age.
The circuit diagram will tell me what values to dig out from my mouldy
old box of spare resistors and capacitors :-)
Photos of the board ar available for the terminally curious. The
engineering is **impressive** - four sprung contacts make the sole
connection between the end cover with the board, and the motor and
light connections.
<hubby off line>
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
I have seen very few service manuals that get down to component level repair
on boards. Generally the manufacturers simply replace the entire unit, in
your case the side panel. For Elna after the side panels became no longer
available they could be sent in to Elna for repair as long as the diaphragm
was not bad, in that case it was unrepairable. Now that Janome owns them the
repair option is off the table as well.
I have a parts chart for the Air Electronic if you think that will help you
email me and I will pass it along
--
Ron Anderson A1 Sewing Machine
18 Dingman Rd Sand Lake, NY 12153
http://www.a1sewingmachine.com
Kate XXXXXX
2008-12-21 14:02:33 UTC
Permalink
Post by Ron Anderson
Post by Kate XXXXXX
My Elna Lotus Stella Air Electronic has blown a capacitor or summat...
Anyone got a circuit diagram? Alan can fix it, but needs the diagram to
determine particular component deatils.
<hubby on the line>
One 0.047 uF capacitor is noticably bulged. Two resistors are singed,
one so badly that the colour code is unreadable. Active components
(diodes, power transistor) look OK so I am hopeful that replacing the
damaged passive bits will be enough. I suspect that the capacitor
failed first, I believe they are prone to breakdown with age.
The circuit diagram will tell me what values to dig out from my mouldy
old box of spare resistors and capacitors :-)
Photos of the board ar available for the terminally curious. The
engineering is **impressive** - four sprung contacts make the sole
connection between the end cover with the board, and the motor and
light connections.
<hubby off line>
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
I have seen very few service manuals that get down to component level repair
on boards. Generally the manufacturers simply replace the entire unit, in
your case the side panel. For Elna after the side panels became no longer
available they could be sent in to Elna for repair as long as the diaphragm
was not bad, in that case it was unrepairable. Now that Janome owns them the
repair option is off the table as well.
I have a parts chart for the Air Electronic if you think that will help you
email me and I will pass it along
Sorry - your post slipped the net!

Do you have a spare circuit board? Working or not... If we can see the
parts numbers/codes on our dead bits, it'll help.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
Ron Anderson
2008-12-21 16:06:05 UTC
Permalink
(snip)
Post by Kate XXXXXX
Post by Ron Anderson
repair option is off the table as well.
I have a parts chart for the Air Electronic if you think that will help
you email me and I will pass it along
Sorry - your post slipped the net!
Do you have a spare circuit board? Working or not... If we can see the
parts numbers/codes on our dead bits, it'll help.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
I have one from a Carina only. The other notable is the machines on this
side of the pond are for 110 volt.
I will take a photo if you like. let me know.
--
Ron Anderson A1 Sewing Machine
18 Dingman Rd Sand Lake, NY 12153
http://www.a1sewingmachine.com
Kate XXXXXX
2008-12-21 17:31:06 UTC
Permalink
Post by Ron Anderson
(snip)
Post by Kate XXXXXX
Post by Ron Anderson
repair option is off the table as well.
I have a parts chart for the Air Electronic if you think that will help
you email me and I will pass it along
Sorry - your post slipped the net!
Do you have a spare circuit board? Working or not... If we can see the
parts numbers/codes on our dead bits, it'll help.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
I have one from a Carina only. The other notable is the machines on this
side of the pond are for 110 volt.
I will take a photo if you like. let me know.
Please would you. I *think* Alan has it sorted, and he's gone off to
Maplin to get the bits, but it may give us some confirmation if things
are not quite right... The reply address here works.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
Ron Anderson
2008-12-21 20:55:25 UTC
Permalink
Post by Kate XXXXXX
Post by Ron Anderson
(snip)
Post by Kate XXXXXX
Post by Ron Anderson
repair option is off the table as well.
I have a parts chart for the Air Electronic if you think that will help
you email me and I will pass it along
Sorry - your post slipped the net!
Do you have a spare circuit board? Working or not... If we can see the
parts numbers/codes on our dead bits, it'll help.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
I have one from a Carina only. The other notable is the machines on this
side of the pond are for 110 volt.
I will take a photo if you like. let me know.
Please would you. I *think* Alan has it sorted, and he's gone off to
Maplin to get the bits, but it may give us some confirmation if things
are not quite right... The reply address here works.
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
OK I will get at it
--
Ron Anderson A1 Sewing Machine
18 Dingman Rd Sand Lake, NY 12153
http://www.a1sewingmachine.com
Alan Dicey
2008-12-19 16:08:04 UTC
Permalink
Info from our Old Sewing Machine Guys indicates that Janome purchased
the name and stock only, not the spares or documentation, which is
consequently difficult to get hold of. Also the board manufacturer
(probably Swiss) went out of business many years ago.

The machine was still working before I took the board out, although the
motor control wasn't quite right, not giving the full range of speeds
expected from the slider.

On extracting the board I found several discretes showing signs of
failure, getting too hot :-) Two of the wires from the board to the
pneumatically-actuated voltage divider worked by the foot pedal had been
trapped under the circuit board, and one showed signs of the insulation
having been punctured by a wire tail on the board.

This is a board that can be reverse engineered relatively easily: all
discrete components, the most complex semiconductor being the triac at
the heart of it all. There's a diac in the gate feed and several
diodes. Big chunky metallised paper capacitors, one of which has a
serious bulge, but can still be read as 0.047µF. Easily-readable metal
film resistors, except that two of them have been cooked so much that
the colour-code bands are blackened or flaked off. It's these two
components that I'm trying to get values for. There are also three
chokes that have no markings at all - but they show no signs of failure.

The board bears the identification number TA 431100 - 1

Ideally I'd like a circuit diagram, but it begins to look as though they
are scarce.

If anyone has a working Stella tsp Air electronic and is prepared to
take the end cover off and photograph the component side of the circuit
board, I'd be very grateful. Just unplug the power cord and controller
line and undo the four screws. The end will appear to be spring-loaded
but don't worry, this is the four neatly-engineered sprung contacts that
take the control output to the motor and lamp in the main chassis. I
will get Kate to post pictures of the board from our machine, showing
which components are unreadable.

I'm working on reverse-engineering the circuit diagram. The triac is a
Philips BT138 500E, a relatively well-known device, and the circuit is
obviously a triac motor control circuit, but it's not my area of
expertise and it isn't quite like any of the simple examples I've come
across up to now. The motor is connected across a bridge rectifier, for
a start.
robb
2008-12-19 18:05:17 UTC
Permalink
Post by Alan Dicey
Info from our Old Sewing Machine Guys indicates that Janome
purchased
Post by Alan Dicey
the name and stock only, not the spares or documentation, which is
consequently difficult to get hold of. Also the board
manufacturer
Post by Alan Dicey
(probably Swiss) went out of business many years ago.
The machine was still working before I took the board out,
although the
Post by Alan Dicey
motor control wasn't quite right, not giving the full range of
speeds
Post by Alan Dicey
expected from the slider.
On extracting the board I found several discretes showing signs of
failure, getting too hot :-) Two of the wires from the board
to the
Post by Alan Dicey
pneumatically-actuated voltage divider worked by the foot pedal had been
trapped under the circuit board, and one showed signs of the
insulation
Post by Alan Dicey
having been punctured by a wire tail on the board.
This is a board that can be reverse engineered relatively
easily:

Alan are you going to etch your own board :)
Post by Alan Dicey
all
discrete components, the most complex semiconductor being the
triac at
Post by Alan Dicey
the heart of it all. There's a diac in the gate feed and
several
Post by Alan Dicey
diodes. Big chunky metallised paper capacitors, one of which
has a
Post by Alan Dicey
serious bulge, but can still be read as 0.047µF.
Easily-readable metal
Post by Alan Dicey
film resistors, except that two of them have been cooked so
much that
Post by Alan Dicey
the colour-code bands are blackened or flaked off. It's these
two
Post by Alan Dicey
components that I'm trying to get values for. There are also
three
Post by Alan Dicey
chokes that have no markings at all - but they show no signs of failure.
i once lucked out with some burned resitors mounted close to the
board where the tops were black but the bottom next to the board
some how remained intact enough to get the color bands

FWIW

if you do not already know about these there are a couple of
electronic usenet groups at
sci.electronics.{basics, components, repair} that have some
really helpful contributors. They have been extremely helpful
with several component, schematic and circuit problems. Probably
good enough to give a pretty good guess at the values of your
resitors given a schematic and what it does or is used for.
Post by Alan Dicey
The board bears the identification number TA 431100 - 1
Ideally I'd like a circuit diagram, but it begins to look as
though they
Post by Alan Dicey
are scarce.
If anyone has a working Stella tsp Air electronic and is
prepared to
Post by Alan Dicey
take the end cover off and photograph the component side of the circuit
board, I'd be very grateful. Just unplug the power cord and
controller
Post by Alan Dicey
line and undo the four screws. The end will appear to be
spring-loaded
Post by Alan Dicey
but don't worry, this is the four neatly-engineered sprung
contacts that
Post by Alan Dicey
take the control output to the motor and lamp in the main
chassis. I
Post by Alan Dicey
will get Kate to post pictures of the board from our machine,
showing
Post by Alan Dicey
which components are unreadable.
I'm working on reverse-engineering the circuit diagram. The
triac is a
Post by Alan Dicey
Philips BT138 500E, a relatively well-known device, and the
circuit is
Post by Alan Dicey
obviously a triac motor control circuit, but it's not my area
of
Post by Alan Dicey
expertise and it isn't quite like any of the simple examples
I've come
Post by Alan Dicey
across up to now. The motor is connected across a bridge
rectifier, for
Post by Alan Dicey
a start.
are you using a PCB or schemtaic software to draw the board and
circuit ?
good luck and fun with the reverse engineering

robb
Alan Dicey
2008-12-19 20:42:21 UTC
Permalink
Post by robb
are you using a PCB or schemtaic software to draw the board and
circuit ?
good luck and fun with the reverse engineering
No: sketching the tracks and then adding the components "seeing through"
the pcb to start with, then converting that to a conventional net, then
trying to manipulate it to make it look like a circuit with AC input at
one side. Fortunately there aren't too many components. When I'm done
I'll probably draw it up in Visio.

It is vexing that the chokes have no information on them at all to give
a clue about their value. Fortunately they are robust devices and show
no signs of age.

I suspect the bulged capacitor to simply have failed of old age. That
alone may have been enough to fry the resistors. Need to disinter my
solder-sucker to get the capacitors off the board.

As a last resort I'll isolate one end of each of the fried resistors and
measure their values. But I'm nervous of unsoldering the resistors
themselves, as I suspect they'll fall apart.
Kate XXXXXX
2008-12-19 23:57:09 UTC
Permalink
Post by robb
are you using a PCB or schemtaic software to draw the board and
circuit ?
good luck and fun with the reverse engineering
robb
Pics here:
http://www.flickr.com/photos/***@N08/3121663500/
http://www.flickr.com/photos/***@N08/3121663192/in/photostream/

If you can't see enough, I can email you them... BIG pix!
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
robb
2008-12-20 06:43:49 UTC
Permalink
Post by Kate XXXXXX
Post by robb
are you using a PCB or schemtaic software to draw the board
and
Post by Kate XXXXXX
Post by robb
circuit ?
good luck and fun with the reverse engineering
robb
If you can't see enough, I can email you them... BIG pix!
those are great, I could see enough to say OUCH !

looks like one of the resistors returned from whence it came
"ashes to ashes, dust to dust"
i like the window cut for the other resistor, there must be some
expectation for that one to get hot.

robb
Kate XXXXXX
2008-12-20 08:54:01 UTC
Permalink
Post by robb
Post by Kate XXXXXX
Post by robb
are you using a PCB or schemtaic software to draw the board
and
Post by Kate XXXXXX
Post by robb
circuit ?
good luck and fun with the reverse engineering
robb
If you can't see enough, I can email you them... BIG pix!
those are great, I could see enough to say OUCH !
Cannon digital SLR with 10X optical zoom. :)
Post by robb
looks like one of the resistors returned from whence it came
"ashes to ashes, dust to dust"
i like the window cut for the other resistor, there must be some
expectation for that one to get hot.
Yup, that's what Alan thought...
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
IMS
2008-12-19 16:53:47 UTC
Permalink
http://www.whitesewingcenter.com/manuals.php

..or email Ray directly, I'm sure he'll help you.

-Irene

On Fri, 19 Dec 2008 08:18:09 +0000, Kate XXXXXX
Post by Kate XXXXXX
My Elna Lotus Stella Air Electronic has blown a capacitor or summat...
Anyone got a circuit diagram? Alan can fix it, but needs the diagram to
determine particular component deatils.
<hubby on the line>
One 0.047 uF capacitor is noticably bulged. Two resistors are singed,
one so badly that the colour code is unreadable. Active components
(diodes, power transistor) look OK so I am hopeful that replacing the
damaged passive bits will be enough. I suspect that the capacitor
failed first, I believe they are prone to breakdown with age.
The circuit diagram will tell me what values to dig out from my mouldy
old box of spare resistors and capacitors :-)
Photos of the board ar available for the terminally curious. The
engineering is **impressive** - four sprung contacts make the sole
connection between the end cover with the board, and the motor and
light connections.
<hubby off line>
Kate XXXXXX
2008-12-19 17:16:29 UTC
Permalink
Post by IMS
http://www.whitesewingcenter.com/manuals.php
..or email Ray directly, I'm sure he'll help you.
I have the proper machine manual for all my Elna Lotus machines, but not
the service manual, which doesn't appear to be anywhere much...
--
Kate XXXXXX R.C.T.Q Madame Chef des Trolls
Lady Catherine, Wardrobe Mistress of the Chocolate Buttons
http://www.katedicey.co.uk
Click on Kate's Pages and explore!
IMS
2008-12-19 19:19:57 UTC
Permalink
Yes, email Ray - I'm sure he has a service manual and he may send it
to you for free or for a minimal charge. Tell him Irene in Ithaca
sent you :)

-Irene

On Fri, 19 Dec 2008 17:16:29 +0000, Kate XXXXXX
Post by Kate XXXXXX
Post by IMS
http://www.whitesewingcenter.com/manuals.php
..or email Ray directly, I'm sure he'll help you.
I have the proper machine manual for all my Elna Lotus machines, but not
the service manual, which doesn't appear to be anywhere much...
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