I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

On 6 Jan 2004 13:14:51 -0500, (Len Moskowitz) wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.


Is a 300ma supply enough?? That's less than 5 watts.

Alan Peterman wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Is a 300ma supply enough?? That's less than 5 watts.

The folks at Thorens USA say that's correct.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

I wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Is a 300ma supply enough?? That's less than 5 watts.

The folks at Thorens USA say that's correct.

The Thorens manual for the TD-146 (also TD-166 MKII) says: 16 VAC @ 140 mA
--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

I wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Is a 300ma supply enough?? That's less than 5 watts.

The folks at Thorens USA say that's correct.

The Thorens manual for the TD-146 (also TD-166 MKII) says: 16 VAC @ 140 mA
--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

I wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Is a 300ma supply enough?? That's less than 5 watts.

The folks at Thorens USA say that's correct.

The Thorens manual for the TD-146 (also TD-166 MKII) says: 16 VAC @ 140 mA
--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

I wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Is a 300ma supply enough?? That's less than 5 watts.

The folks at Thorens USA say that's correct.

The Thorens manual for the TD-146 (also TD-166 MKII) says: 16 VAC @ 140 mA
--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Alan Peterman wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Is a 300ma supply enough?? That's less than 5 watts.

The folks at Thorens USA say that's correct.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Alan Peterman wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Is a 300ma supply enough?? That's less than 5 watts.

The folks at Thorens USA say that's correct.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Alan Peterman wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Is a 300ma supply enough?? That's less than 5 watts.

The folks at Thorens USA say that's correct.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

On 6 Jan 2004 13:14:51 -0500, (Len Moskowitz) wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.


Is a 300ma supply enough?? That's less than 5 watts.

On 6 Jan 2004 13:14:51 -0500, (Len Moskowitz) wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.


Is a 300ma supply enough?? That's less than 5 watts.

Len Moskowitz wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?

http://www.theanalogdept.com/manuals.htm - may or may not be of use,
someone recently posted the link in some similar context, so I happened
to have it in my browser history for yesterday.

Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Len Moskowitz wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?

http://www.theanalogdept.com/manuals.htm - may or may not be of use,
someone recently posted the link in some similar context, so I happened
to have it in my browser history for yesterday.

Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Len Moskowitz wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?

http://www.theanalogdept.com/manuals.htm - may or may not be of use,
someone recently posted the link in some similar context, so I happened
to have it in my browser history for yesterday.

Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Len Moskowitz wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?

Robert Gault wrote:

What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?

The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Len Moskowitz wrote:
Robert Gault wrote:


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?


The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Robert Gault wrote:

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Two of the bridge diodes were dead. While I was in there I replaced the
two electrolytic caps and the LM324N. It's working!

By the way, I've found a source for the service manual. When it arrives
I'll try to upload it to one of the turntable site (probably
www.vinylengine.com).

Thanks to all for the help.
--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Robert Gault wrote:

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Two of the bridge diodes were dead. While I was in there I replaced the
two electrolytic caps and the LM324N. It's working!

By the way, I've found a source for the service manual. When it arrives
I'll try to upload it to one of the turntable site (probably
www.vinylengine.com).

Thanks to all for the help.
--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Robert Gault wrote:

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Two of the bridge diodes were dead. While I was in there I replaced the
two electrolytic caps and the LM324N. It's working!

By the way, I've found a source for the service manual. When it arrives
I'll try to upload it to one of the turntable site (probably
www.vinylengine.com).

Thanks to all for the help.
--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Robert Gault wrote:

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Two of the bridge diodes were dead. While I was in there I replaced the
two electrolytic caps and the LM324N. It's working!

By the way, I've found a source for the service manual. When it arrives
I'll try to upload it to one of the turntable site (probably
www.vinylengine.com).

Thanks to all for the help.
--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

On my TD166, I hadn't used it for about a year. When I finally did turn it
on, I discovered that one of the power supply electrolytic caps had shorted.

Pete

Robert Gault wrote in message
...
Len Moskowitz wrote:
Robert Gault wrote:


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?


The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or
a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

On my TD166, I hadn't used it for about a year. When I finally did turn it
on, I discovered that one of the power supply electrolytic caps had shorted.

Pete

Robert Gault wrote in message
...
Len Moskowitz wrote:
Robert Gault wrote:


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?


The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or
a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

On my TD166, I hadn't used it for about a year. When I finally did turn it
on, I discovered that one of the power supply electrolytic caps had shorted.

Pete

Robert Gault wrote in message
...
Len Moskowitz wrote:
Robert Gault wrote:


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?


The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or
a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

On my TD166, I hadn't used it for about a year. When I finally did turn it
on, I discovered that one of the power supply electrolytic caps had shorted.

Pete

Robert Gault wrote in message
...
Len Moskowitz wrote:
Robert Gault wrote:


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?


The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or
a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Len Moskowitz wrote:
Robert Gault wrote:


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?


The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Len Moskowitz wrote:
Robert Gault wrote:


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?


The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Len Moskowitz wrote:
Robert Gault wrote:


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?


The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

Make sure that none of the diodes in the full wave bridge have blown.
This is frequently a problem.

Robert Gault wrote:

What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?

The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Robert Gault wrote:

What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?

The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Robert Gault wrote:

What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?

The regulator diodes are overheating, indicating a short somewhere. The
two analog ICs (LM324N and MC34001) are not getting Vcc. I disconnected
the motor (which should be run by 110 VAC anyway) and saw no change (as
expected). I pulled both ICs and saw no change. There's one
small three-terminal device that could be either a voltage regulator or a pass
transistor -- that's the next thing I'll look at.

Anyone know what voltage Thorens runs its analog ICs at?

I'm trying to track down a schematic or service manual for the TD-146.
All leads appreciated.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

Len Moskowitz wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?

Len Moskowitz wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?

Len Moskowitz wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


What voltage, if any, do you read at the motor terminals? Likewise as
you move from the wall mart through the PCB board?

On 6 Jan 2004 13:14:51 -0500, (Len Moskowitz)
wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


The LM324 often fails on this model. chuck

On 6 Jan 2004 13:14:51 -0500, (Len Moskowitz)
wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


The LM324 often fails on this model. chuck

On 6 Jan 2004 13:14:51 -0500, (Len Moskowitz)
wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


The LM324 often fails on this model. chuck

On 6 Jan 2004 13:14:51 -0500, (Len Moskowitz)
wrote:

I have a Thorens TD-146 turntable whose motor doesn't turn. It's being
fed by a new 16 VAC/300 mA wall wart.

Anyone know what typically goes wrong with these? Anyone have
schematics?

From looking at the PCB, it seems to have a full wave rectifier circuit,
one transistor (with no identification), an LM324, an MC34001 and
miscellaneous passive parts (caps and resistors).

What kind of waveform drives the motor's four terminals?


The LM324 often fails on this model. chuck