I need your help repairing the voltage conversion circuit of the Bosch
WFL2061BY washing machine. I have the following questions:

1) No operating lights etc. are on. Visual inspection shows a damaged
resistor (first two bands brown and black, next band difficult to tell
- possibly brown, gold or even yellow). As far as I can tell no fuse
is fitted - is this normal? A fuse seems to be essential to protect
against possible overcurrent conditions.

2) The damaged resistor is directly connected to the mains in series
with a transformer (which I suspect is used to derive the low voltage
for driving the relays). I have experimented with
a 100R resistor (1/4 Watt) connected to 220V, but it is immediately
burned out.
Four (1/4 Watt) resistors of 10k in parallel also got hot in a few
seconds. My initial guess would be that the damaged resistor provides
current limiting?

3) If the damaged resistor provides current limiting, why is it placed
on the high voltage (220V) side?

4) A number of diodes (likely 1N4001) also seems to be connected to
the high voltage side, before the transformer. If they form a half-
wave or full-wave rectifier, why do they connect the diodes before the
transformer (on the high voltage side)?

5) It is possible that some other components also got damaged. From
visual inspection I cannot confirm damage to other components. In
circuit measurements of the diodes show about 4.5k in one direction
and infinity in the other. An 8 pin IC TP209P is found close to the
(small) transformer. The voltage regulator is a BT916 (or BTB16 -
difficult to tell from visual inspection). Any suggestions on how to
proceed?

Best regards,
Theo van der Merwe

wrote in message
ups.com...
I need your help repairing the voltage conversion circuit of the Bosch
WFL2061BY washing machine. I have the following questions:

1) No operating lights etc. are on. Visual inspection shows a damaged
resistor (first two bands brown and black, next band difficult to tell
- possibly brown, gold or even yellow). As far as I can tell no fuse
is fitted - is this normal? A fuse seems to be essential to protect
against possible overcurrent conditions.

2) The damaged resistor is directly connected to the mains in series
with a transformer (which I suspect is used to derive the low voltage
for driving the relays). I have experimented with
a 100R resistor (1/4 Watt) connected to 220V, but it is immediately
burned out.
Four (1/4 Watt) resistors of 10k in parallel also got hot in a few
seconds. My initial guess would be that the damaged resistor provides
current limiting?

3) If the damaged resistor provides current limiting, why is it placed
on the high voltage (220V) side?

4) A number of diodes (likely 1N4001) also seems to be connected to
the high voltage side, before the transformer. If they form a half-
wave or full-wave rectifier, why do they connect the diodes before the
transformer (on the high voltage side)?

5) It is possible that some other components also got damaged. From
visual inspection I cannot confirm damage to other components. In
circuit measurements of the diodes show about 4.5k in one direction
and infinity in the other. An 8 pin IC TP209P is found close to the
(small) transformer. The voltage regulator is a BT916 (or BTB16 -
difficult to tell from visual inspection). Any suggestions on how to
proceed?

Best regards,
Theo van der Merwe



There's certainly a shorted component which burned up the resistor.
Resistors don't just burn up on their own.

On Jun 4, 8:21 pm, "James Sweet" wrote:
wrote in message

ups.com...



I need your help repairing the voltage conversion circuit of the Bosch
WFL2061BY washing machine. I have the following questions:

1) No operating lights etc. are on. Visual inspection shows a damaged
resistor (first two bands brown and black, next band difficult to tell
- possibly brown, gold or even yellow). As far as I can tell no fuse
is fitted - is this normal? A fuse seems to be essential to protect
against possible overcurrent conditions.

2) The damaged resistor is directly connected to the mains in series
with a transformer (which I suspect is used to derive the low voltage
for driving the relays). I have experimented with
a 100R resistor (1/4 Watt) connected to 220V, but it is immediately
burned out.
Four (1/4 Watt) resistors of 10k in parallel also got hot in a few
seconds. My initial guess would be that the damaged resistor provides
current limiting?

3) If the damaged resistor provides current limiting, why is it placed
on the high voltage (220V) side?

4) A number of diodes (likely 1N4001) also seems to be connected to
the high voltage side, before the transformer. If they form a half-
wave or full-wave rectifier, why do they connect the diodes before the
transformer (on the high voltage side)?

5) It is possible that some other components also got damaged. From
visual inspection I cannot confirm damage to other components. In
circuit measurements of the diodes show about 4.5k in one direction
and infinity in the other. An 8 pin IC TP209P is found close to the
(small) transformer. The voltage regulator is a BT916 (or BTB16 -
difficult to tell from visual inspection). Any suggestions on how to
proceed?

Best regards,
Theo van der Merwe

There's certainly a shorted component which burned up the resistor.
Resistors don't just burn up on their own.

Thanks for the email message and feedback. The problem occurred when
testing the pumping out of water (which wasn't working at all -
everything else seems OK). However, I have disconnected all the
external connections to the motor and pump from the circuit board. Any
suggestions on how to proceed with fault finding (assuming some
component is shorted on the circuit board)? At present I don't
understand the power supply design on the circuit board.

Best regards,
Theo van der Merwe

wrote in message
oups.com...
On Jun 4, 8:21 pm, "James Sweet" wrote:
wrote in message

ups.com...



I need your help repairing the voltage conversion circuit of the Bosch
WFL2061BY washing machine. I have the following questions:

1) No operating lights etc. are on. Visual inspection shows a damaged
resistor (first two bands brown and black, next band difficult to tell
- possibly brown, gold or even yellow). As far as I can tell no fuse
is fitted - is this normal? A fuse seems to be essential to protect
against possible overcurrent conditions.


there's likely a thermal fuse in the transformer windings. If the motor
pulls anywhere close to 15A they figure your circuit breaker will do the
trick. BTW fuses don't protect semiconductors, they're too slow.

2) The damaged resistor is directly connected to the mains in series
with a transformer (which I suspect is used to derive the low voltage
for driving the relays). I have experimented with
a 100R resistor (1/4 Watt) connected to 220V, but it is immediately
burned out.
Four (1/4 Watt) resistors of 10k in parallel also got hot in a few
seconds. My initial guess would be that the damaged resistor provides
current limiting?


Something's shorted and drawing too much current. A metal film resistor
tends to be a pretty good fuse in many cases.

3) If the damaged resistor provides current limiting, why is it placed
on the high voltage (220V) side?

Less current, smaller resistor, cheaper. Also, it ensures that the
transformer is not hot in the event of a fault.

4) A number of diodes (likely 1N4001) also seems to be connected to
the high voltage side, before the transformer. If they form a half-
wave or full-wave rectifier, why do they connect the diodes before the
transformer (on the high voltage side)?

The AC cannot be rectified prior to your transformer. Can't can't can't.
I'm confused as to what you've got here... does the main power all run
through the transformer, or is the transformer just to step down the voltage
for powering the electronics with the AC going to power the motor relays? I
don't think you've got any motor relays if you've got Triacs (see below).

5) It is possible that some other components also got damaged. From
visual inspection I cannot confirm damage to other components. In
circuit measurements of the diodes show about 4.5k in one direction
and infinity in the other. An 8 pin IC TP209P is found close to the
(small) transformer. The voltage regulator is a BT916 (or BTB16 -
difficult to tell from visual inspection). Any suggestions on how to
proceed?

The BTB16 is a 16A Triac, not a regulator. It's likely used to switch on
the motor or pump and possibly control the speed depending on the complexity
of the control circuit.

First, can you confirm that if you physically disconnect all wiring from the
pump, that the problem persists? That would effectively rule out the pump.
I might try powering the pump directly by attaching a line cord and confirm
that it works. The triac which controls (I am assuming here, the pump MAY
be controlled by a relay as it only needs to operate at one speed) has
virtually no resistance when biased by the gate voltage, the only thing
limiting the current draw is the load which is in this case is the pump. So
let's rule it out.

If in fact the pump is fine, and if removing it from the circuit does not
eliminate the problem of the resistor smoking, I'd try removing the triac
which controls the pump. When triacs fail they either stop working or fail
shorted. Neither of these matches your scenario. Check the pump wiring and
make sure there are no shorts to ground or shorts from hot to neutral lead.

If it's a relay and not a triac which controls the pump I'd take a good look
at it... are the contacts burnt? What else is around it in the circuit?

Can you confirm the writing on the 8-pin DIP? If there are various motor
speeds it could be a pulse width modulator driving the triac, but I come up
empty with "TP209P"... TP209 yields a DC-to-DC upconverter, 5VDC in and
15VDC out, 50mA rating...

Dave

Best regards,
Theo van der Merwe

There's certainly a shorted component which burned up the resistor.
Resistors don't just burn up on their own.

Thanks for the email message and feedback. The problem occurred when
testing the pumping out of water (which wasn't working at all -
everything else seems OK). However, I have disconnected all the
external connections to the motor and pump from the circuit board. Any
suggestions on how to proceed with fault finding (assuming some
component is shorted on the circuit board)? At present I don't
understand the power supply design on the circuit board.

Best regards,
Theo van der Merwe

On Jun 5, 8:43 pm, "Dave" wrote:
wrote in message

oups.com...



On Jun 4, 8:21 pm, "James Sweet" wrote:
wrote in message

roups.com...

I need your help repairing the voltage conversion circuit of the Bosch
WFL2061BY washing machine. I have the following questions:

1) No operating lights etc. are on. Visual inspection shows a damaged
resistor (first two bands brown and black, next band difficult to tell
- possibly brown, gold or even yellow). As far as I can tell no fuse
is fitted - is this normal? A fuse seems to be essential to protect
against possible overcurrent conditions.

there's likely a thermal fuse in the transformer windings. If the motor
pulls anywhere close to 15A they figure your circuit breaker will do the
trick. BTW fuses don't protect semiconductors, they're too slow.

Thanks for the feedback, now I understand better.



2) The damaged resistor is directly connected to the mains in series
with a transformer (which I suspect is used to derive the low voltage
for driving the relays). I have experimented with
a 100R resistor (1/4 Watt) connected to 220V, but it is immediately
burned out.
Four (1/4 Watt) resistors of 10k in parallel also got hot in a few
seconds. My initial guess would be that the damaged resistor provides
current limiting?

Something's shorted and drawing too much current. A metal film resistor
tends to be a pretty good fuse in many cases.

3) If the damaged resistor provides current limiting, why is it placed
on the high voltage (220V) side?

Less current, smaller resistor, cheaper. Also, it ensures that the
transformer is not hot in the event of a fault.

Thanks for the feedback, now I understand better.

4) A number of diodes (likely 1N4001) also seems to be connected to
the high voltage side, before the transformer. If they form a half-
wave or full-wave rectifier, why do they connect the diodes before the
transformer (on the high voltage side)?

The AC cannot be rectified prior to your transformer. Can't can't can't.
I'm confused as to what you've got here... does the main power all run
through the transformer, or is the transformer just to step down the voltage
for powering the electronics with the AC going to power the motor relays? I
don't think you've got any motor relays if you've got Triacs (see below).


I can send you a JPEG of the circuit board if it can help, but below
is a brief description of the connections:

From mains to multipole switch (selecting program) to resistor R1 (the
damaged resistor of unknown value, probably 2W from the size)
From mains to multipole switch (selecting program) to capacitor C1
(and R1). C1 is a large 0.22uF 275V AC
From mains to multipole switch (selecting program) to resistor R2 (Red
Red Black Orange Red or other way round). Eventually the connection
from R2 ends up at a connector at the edge of the circuit board (e.g.
could be motor).

From mains to multipole switch (selecting program) to connector (could
be pump/motor).

From resistor R1 (other end) to diode D1 (Anode)
From diode D1 (Cathode) to D2 (Cathode)
From diode D1 (Cathode) to C2 (large 400V 10uF). The other end of C2
is marked -, so it could be polarised capacitor (looks like an
electrolytic capacitor).
From diode D1 to transformer terminal 1

From mains live (other connection) to multipole switch to capacitor C1
(other end)
From mains live (other connection) to relay
From mains live (other connection) to blue component with 2
connections marked S10 K275 0013
From mains live (other connection) to transformer terminal 2
From mains live (other connection) to pins 1,2,3,7,8 of IC 1 (TOP92P)
From mains live (other connection) to pin 1 of IC2 (BTB16T)
From mains live (other connection) to many other components (e.g.
small components looking like surface mount capacitors)

From transformer terminal 3 to diode D3 (Cathode)
From transformer terminal 3 to pin 5 IC1 (TOP92P)
From transformer terminal 4 to diode D4 (Anode)

From diode D4 (Cathode) to capacitor C3 with thick trace (presumably
positive, other end marked - . Looks like electrolytic capacitor 16V
100uF).
From diode D4 (Cathode) to small diode D5 (Anode). D5 looks like
1N4148??
From diode D4 (Cathode) to Relay R1 (on the circuit board a plus sign
is found next to the connection to the relay).

From relay R1 to connector (motor/pump?)

Please let me know if you need more information. The presence of a
polarised capacitor C2 of 400V connected to the mains supply via diode
D1 would seem to indicate half wave rectification? If so, I can't
quite understand why it is rectified prior to the transformer.


5) It is possible that some other components also got damaged. From
visual inspection I cannot confirm damage to other components. In
circuit measurements of the diodes show about 4.5k in one direction
and infinity in the other. An 8 pin IC TP209P is found close to the
(small) transformer. The voltage regulator is a BT916 (or BTB16 -
difficult to tell from visual inspection). Any suggestions on how to
proceed?

The BTB16 is a 16A Triac, not a regulator. It's likely used to switch on
the motor or pump and possibly control the speed depending on the complexity
of the control circuit.

Thanks for the feedback.

First, can you confirm that if you physically disconnect all wiring from the
pump, that the problem persists? That would effectively rule out the pump.

Yes, at present I have disconnected all connectors (motor, pump etc.)
from the circuit board.

I might try powering the pump directly by attaching a line cord and confirm
that it works. The triac which controls (I am assuming here, the pump MAY
be controlled by a relay as it only needs to operate at one speed) has
virtually no resistance when biased by the gate voltage, the only thing
limiting the current draw is the load which is in this case is the pump. So
let's rule it out.

Thanks for the feedback. How do I actually test the pump? Should I
fill the washing machine with water before testing the pump and see if
water exits the drain? Or is it possible to test the pump without
fluid? Anyway, at present the pump is not connected to the circuit
board.



If in fact the pump is fine, and if removing it from the circuit does not
eliminate the problem of the resistor smoking, I'd try removing the triac
which controls the pump. When triacs fail they either stop working or fail
shorted. Neither of these matches your scenario. Check the pump wiring and
make sure there are no shorts to ground or shorts from hot to neutral lead.

If the triac fail shorted it could explain the excessive current
drain?

The triac is connected to the circuit board via a large heatsink, so
it seems difficult to remove (hence test for shorts). Any suggestions?


If it's a relay and not a triac which controls the pump I'd take a good look
at it... are the contacts burnt? What else is around it in the circuit?


When I trace the 3pin connector going to the pump back to the circuit
board, it seems that a relay (10A 125V AC, 12VDC) controls the pump.

Visual inspection of the circuit board indicates damage to resistor
R1. Black soot is seen in the vicinity of diodes D1, D2, D3. The
diodes does not seem damaged from visual inspection, although the
wires of the diodes are not shiny, indicating current drain.

Can you confirm the writing on the 8-pin DIP? If there are various motor
speeds it could be a pulse width modulator driving the triac, but I come up
empty with "TP209P"... TP209 yields a DC-to-DC upconverter, 5VDC in and
15VDC out, 50mA rating...

Sorry, it is actually TOP209P. At the top is written K021 and at
bottom 1067 1B,

Thanks for all your kind help.
Best regards,
Theo

Dave

Best regards,
Theo van der Merwe

There's certainly a shorted component which burned up the resistor.
Resistors don't just burn up on their own.

Thanks for the email message and feedback. The problem occurred when
testing the pumping out of water (which wasn't working at all -
everything else seems OK). However, I have disconnected all the
external connections to the motor and pump from the circuit board. Any
suggestions on how to proceed with fault finding (assuming some
component is shorted on the circuit board)? At present I don't
understand the power supply design on the circuit board.

Best regards,
Theo van der Merwe

wrote in message
ups.com...



I can send you a JPEG of the circuit board if it can help, but below
is a brief description of the connections:

A picture is worth a thousand words... just remove the word "delete" from my
email address.



If so, I can't
quite understand why it is rectified prior to the transformer.


Nor can I. The transformer would only produce the other half of the wave on
the secondaries. This can't be right.


Yes, at present I have disconnected all connectors (motor, pump etc.)
from the circuit board.

Thanks for the feedback. How do I actually test the pump? Should I
fill the washing machine with water before testing the pump and see if
water exits the drain? Or is it possible to test the pump without
fluid? Anyway, at present the pump is not connected to the circuit
board.


Test the pump wiring harness. Look for a short.

Assuming the pump to operate at mains voltage, just figure out which pins on
the pump connector are for power, connect up a reasonable-guage power cord
and plug it in. We're not trying to determine if this thing pumps water...
at this point we don't really care. We just want to make sure that the
windings aren't shorted and that the pump will start and run. It won't hurt
it to run it dry.




If the triac fail shorted it could explain the excessive current
drain?

That was my original thought, but I had some reservations, hence my
questions about the existence of a relay which you have confirmed. The pump
only operates at one speed, so can be controlled using a relay as opposed to
a triac. The triac likely controls the motor so you can have slow-speed
agitation and high-speed spin with no mechanical transmission. IF the triac
controlled the pump and IF the triac were shorted, the pump would simply run
all the time. This is not the case.


The triac is connected to the circuit board via a large heatsink, so
it seems difficult to remove (hence test for shorts). Any suggestions?

Confirm that the wash/spin motor works and that it's controlled by the large
triac and move on.


If it's a relay and not a triac which controls the pump I'd take a good
look
at it... are the contacts burnt? What else is around it in the circuit?


When I trace the 3pin connector going to the pump back to the circuit
board, it seems that a relay (10A 125V AC, 12VDC) controls the pump.

Visual inspection of the circuit board indicates damage to resistor
R1. Black soot is seen in the vicinity of diodes D1, D2, D3. The
diodes does not seem damaged from visual inspection, although the
wires of the diodes are not shiny, indicating current drain.

Are diodes D1/D2/D3 and resistor R1 on the controlling 12VDC side of the
relay or the load side?

If they're on the load side, and somehow I doubt they are, it's gotta be the
pump or wiring. If they're on the control side, look for a smoked resistor
(and perhaps diode) which limits current through the relay coil. If this
failed it may take down any number of other components in the relay control
circuit.


Sorry, it is actually TOP209P. At the top is written K021 and at
bottom 1067 1B,

Well well well, that's a 3-terminal off-line PWM switch, as predicted. How
many windings/leads on the transformer. The typical circuit diagram in the
TOP209 datasheet shows it being used to derive a stable DC voltage via a
transformer with a bias winding. It's possible that this guy produces the
12VDC to operate the relay. A schematic would be really helpful here.


Thanks for all your kind help.
Best regards,
Theo

Dave

Best regards,
Theo van der Merwe

There's certainly a shorted component which burned up the resistor.
Resistors don't just burn up on their own.

Thanks for the email message and feedback. The problem occurred when
testing the pumping out of water (which wasn't working at all -
everything else seems OK). However, I have disconnected all the
external connections to the motor and pump from the circuit board. Any
suggestions on how to proceed with fault finding (assuming some
component is shorted on the circuit board)? At present I don't
understand the power supply design on the circuit board.

Best regards,
Theo van der Merwe

On Jun 6, 4:39 pm, "Dave" wrote:
wrote in message

ups.com...



I can send you a JPEG of the circuit board if it can help, but below
is a brief description of the connections:

A picture is worth a thousand words... just remove the word "delete" from my
email address.


Unfortunately Google only shows , not the
complete email address (presumably to prevent spam). Can you send a
message to my email address to which I can reply?

Thanks for all your feedback so far.

Best regards,
Theo



If so, I can't
quite understand why it is rectified prior to the transformer.

Nor can I. The transformer would only produce the other half of the wave on
the secondaries. This can't be right.



Yes, at present I have disconnected all connectors (motor, pump etc.)
from the circuit board.

Thanks for the feedback. How do I actually test the pump? Should I
fill the washing machine with water before testing the pump and see if
water exits the drain? Or is it possible to test the pump without
fluid? Anyway, at present the pump is not connected to the circuit
board.

Test the pump wiring harness. Look for a short.

Assuming the pump to operate at mains voltage, just figure out which pins on
the pump connector are for power, connect up a reasonable-guage power cord
and plug it in. We're not trying to determine if this thing pumps water...
at this point we don't really care. We just want to make sure that the
windings aren't shorted and that the pump will start and run. It won't hurt
it to run it dry.



If the triac fail shorted it could explain the excessive current
drain?

That was my original thought, but I had some reservations, hence my
questions about the existence of a relay which you have confirmed. The pump
only operates at one speed, so can be controlled using a relay as opposed to
a triac. The triac likely controls the motor so you can have slow-speed
agitation and high-speed spin with no mechanical transmission. IF the triac
controlled the pump and IF the triac were shorted, the pump would simply run
all the time. This is not the case.



The triac is connected to the circuit board via a large heatsink, so
it seems difficult to remove (hence test for shorts). Any suggestions?

Confirm that the wash/spin motor works and that it's controlled by the large
triac and move on.



If it's a relay and not a triac which controls the pump I'd take a good
look
at it... are the contacts burnt? What else is around it in the circuit?

When I trace the 3pin connector going to the pump back to the circuit
board, it seems that a relay (10A 125V AC, 12VDC) controls the pump.

Visual inspection of the circuit board indicates damage to resistor
R1. Black soot is seen in the vicinity of diodes D1, D2, D3. The
diodes does not seem damaged from visual inspection, although the
wires of the diodes are not shiny, indicating current drain.

Are diodes D1/D2/D3 and resistor R1 on the controlling 12VDC side of the
relay or the load side?

If they're on the load side, and somehow I doubt they are, it's gotta be the
pump or wiring. If they're on the control side, look for a smoked resistor
(and perhaps diode) which limits current through the relay coil. If this
failed it may take down any number of other components in the relay control
circuit.



Sorry, it is actually TOP209P. At the top is written K021 and at
bottom 1067 1B,

Well well well, that's a 3-terminal off-line PWM switch, as predicted. How
many windings/leads on the transformer. The typical circuit diagram in the
TOP209 datasheet shows it being used to derive a stable DC voltage via a
transformer with a bias winding. It's possible that this guy produces the
12VDC to operate the relay. A schematic would be really helpful here.



Thanks for all your kind help.
Best regards,
Theo

Dave

Best regards,
Theo van der Merwe

There's certainly a shorted component which burned up the resistor.
Resistors don't just burn up on their own.

Thanks for the email message and feedback. The problem occurred when
testing the pumping out of water (which wasn't working at all -
everything else seems OK). However, I have disconnected all the
external connections to the motor and pump from the circuit board. Any
suggestions on how to proceed with fault finding (assuming some
component is shorted on the circuit board)? At present I don't
understand the power supply design on the circuit board.

Best regards,
Theo van der Merwe

On 7 Jun, 10:57, wrote:
On Jun 6, 4:39 pm, "Dave" wrote:

wrote in message

oups.com...

I can send you a JPEG of the circuit board if it can help, but below
is a brief description of the connections:

A picture is worth a thousand words... just remove the word "delete" from my
email address.

Unfortunately Google only shows , not the
complete email address (presumably to prevent spam). Can you send a
message to my email address to which I can reply?

Thanks for all your feedback so far.

Best regards,
Theo



If so, I can't
quite understand why it is rectified prior to the transformer.

Nor can I. The transformer would only produce the other half of the wave on
the secondaries. This can't be right.

Yes, at present I have disconnected all connectors (motor, pump etc.)
from the circuit board.

Thanks for the feedback. How do I actually test the pump? Should I
fill the washing machine with water before testing the pump and see if
water exits the drain? Or is it possible to test the pump without
fluid? Anyway, at present the pump is not connected to the circuit
board.

Test the pump wiring harness. Look for a short.

Assuming the pump to operate at mains voltage, just figure out which pins on
the pump connector are for power, connect up a reasonable-guage power cord
and plug it in. We're not trying to determine if this thing pumps water...
at this point we don't really care. We just want to make sure that the
windings aren't shorted and that the pump will start and run. It won't hurt
it to run it dry.

If the triac fail shorted it could explain the excessive current
drain?

That was my original thought, but I had some reservations, hence my
questions about the existence of a relay which you have confirmed. The pump
only operates at one speed, so can be controlled using a relay as opposed to
a triac. The triac likely controls the motor so you can have slow-speed
agitation and high-speed spin with no mechanical transmission. IF the triac
controlled the pump and IF the triac were shorted, the pump would simply run
all the time. This is not the case.

The triac is connected to the circuit board via a large heatsink, so
it seems difficult to remove (hence test for shorts). Any suggestions?

Confirm that the wash/spin motor works and that it's controlled by the large
triac and move on.

If it's a relay and not a triac which controls the pump I'd take a good
look
at it... are the contacts burnt? What else is around it in the circuit?

When I trace the 3pin connector going to the pump back to the circuit
board, it seems that a relay (10A 125V AC, 12VDC) controls the pump.

Visual inspection of the circuit board indicates damage to resistor
R1. Black soot is seen in the vicinity of diodes D1, D2, D3. The
diodes does not seem damaged from visual inspection, although the
wires of the diodes are not shiny, indicating current drain.

Are diodes D1/D2/D3 and resistor R1 on the controlling 12VDC side of the
relay or the load side?

If they're on the load side, and somehow I doubt they are, it's gotta be the
pump or wiring. If they're on the control side, look for a smoked resistor
(and perhaps diode) which limits current through the relay coil. If this
failed it may take down any number of other components in the relay control
circuit.

Sorry, it is actually TOP209P. At the top is written K021 and at
bottom 1067 1B,

Well well well, that's a 3-terminal off-line PWM switch, as predicted. How
many windings/leads on the transformer. The typical circuit diagram in the
TOP209 datasheet shows it being used to derive a stable DC voltage via a
transformer with a bias winding. It's possible that this guy produces the
12VDC to operate the relay. A schematic would be really helpful here.

Thanks for all your kind help.
Best regards,
Theo

Dave

Best regards,
Theo van der Merwe

There's certainly a shorted component which burned up the resistor.
Resistors don't just burn up on their own.

Thanks for the email message and feedback. The problem occurred when
testing the pumping out of water (which wasn't working at all -
everything else seems OK). However, I have disconnected all the
external connections to the motor and pump from the circuit board. Any
suggestions on how to proceed with fault finding (assuming some
component is shorted on the circuit board)? At present I don't
understand the power supply design on the circuit board.

Best regards,
Theo van der Merwe

How about getting a qualified engineer in to fix it before you kill
yourself !

Advice to an amateur? not a chance mate, you might end up frying
yourself.

"Marra" wrote in message
ups.com...

How about getting a qualified engineer in to fix it before you kill
yourself !

Advice to an amateur? not a chance mate, you might end up frying
yourself.


Yes, lots of people kill themselves every year troubleshooting unpowered
appliance circuits.

these types of equipment are far too complicated for the average individual
to ever understand without a degree in engineering... turning a pump on and
off on a timed cycle, whew! that's WAAAAYYYYY beyond me!

Best leave it to the "experts".

The OP obviously has some deductive skills and many times, that and some
perseverance are all it takes to fix something. Thanks for your advice, but
why don't you take your attitude and shove it where the sun don't shine?

Have a great day.

Dave

"Marra" wrote in message
ups.com...
On 7 Jun, 10:57, wrote:
On Jun 6, 4:39 pm, "Dave" wrote:

wrote in message

oups.com...

I can send you a JPEG of the circuit board if it can help, but below
is a brief description of the connections:

A picture is worth a thousand words... just remove the word "delete"
from my
email address.

Unfortunately Google only shows , not the
complete email address (presumably to prevent spam). Can you send a
message to my email address to which I can reply?

On Jun 6, 4:39 pm, "Dave" wrote:
wrote in message

ups.com...



If so, I can't
quite understand why it is rectified prior to the transformer.

Nor can I. The transformer would only produce the other half of the wave on
the secondaries. This can't be right.


According to the connection diagram I sent previously, the mains is
connected directly to diode D1 via a (blown, unknown value) resistor
R1:

From mains to multipole switch (selecting program) to resistor R1.
From resistor R1 (other end) to diode D1 (Anode)
From diode D1 (Cathode) to D2 (Cathode)
From diode D1 (Cathode) to C2

Furthermore, diode D1 is also connected to the transformer:
From diode D1 to transformer terminal 1

If C2 is indeed a polarised electrolytic capacitor (hopefully you'll
be able to visually confirm from the JPEG I sent), it would seem to
imply DC (direct current) - possibly half-wave rectification. Why a
transformer is then connected to the diode D1 is, at present, unclear
to me - I just don't understand it yet.



Yes, at present I have disconnected all connectors (motor, pump etc.)
from the circuit board.

Thanks for the feedback. How do I actually test the pump? Should I
fill the washing machine with water before testing the pump and see if
water exits the drain? Or is it possible to test the pump without
fluid? Anyway, at present the pump is not connected to the circuit
board.

Test the pump wiring harness. Look for a short.

Assuming the pump to operate at mains voltage, just figure out which pins on
the pump connector are for power, connect up a reasonable-guage power cord
and plug it in. We're not trying to determine if this thing pumps water...
at this point we don't really care. We just want to make sure that the
windings aren't shorted and that the pump will start and run. It won't hurt
it to run it dry.

Thanks for the feedback. The electrician that helped us with the
washing machine is unfortunately overseas at present, but the washing
machine seemed to be working correctly (he started a program without
any problems, then stopped the washing machine and pumped out all the
water). However, when we started using the washing machine it would
stop with a flashing light after 20 minutes. When I set the switch to
leave the water in the washing machine, it carried on longer (up to
about 1 hour 20 minutes) - but still did not complete the washing
cycle. When I tried to pump out the water manually the problem with
the shorted resistor occurred. The reason for the flasing light seemed
to be related to the pumping out of water - I set the program to pump
out water, but just heard a 'humming noise', which seems to indicate a
problem with the pump. This would possibly explain why the machine
stopped with a flashing light after 20 minutes - presumaby it tried
(without success) to pump the water out for the next cycle to start.

At present I am not too worried about the pump, as I can always buy a
cheap 'universal' pump to replace if needed. My big worry is about the
electronics. At present I do not know the value of the damaged
resistor (to replace) and whether additional components are damaged.

By the way, the electrician already made a modification with a switch
that we now manually press to start the heating cycle (he also
replaced the thermostat recently).

Are diodes D1/D2/D3 and resistor R1 on the controlling 12VDC side of the
relay or the load side?

If they're on the load side, and somehow I doubt they are, it's gotta be the
pump or wiring. If they're on the control side, look for a smoked resistor
(and perhaps diode) which limits current through the relay coil. If this
failed it may take down any number of other components in the relay control
circuit.


I have measured about 370R between the terminals of relay RL1
connected to the transformer windings (infinfity between other
terminals):

From transformer terminal 4 to diode D4 (Anode)
From diode D4 (Cathode) to Relay R1

So it would seem as though diodes D1/D2/D3 and resistor R1 is
connecting to RL1 (via a transformer) on the controlling side.
The other terminals of RL1 are connected to the connector on the
circuit boad (presumably pump/motor) and the mains, so I assume it
would be the switch controlled by the windings of RL1.

Is it possible to infer the likely value of resistor R1 from the text
description of the connections? I would suspect that activating the
relays could take a few hundred milli-amperes. A 2.5k resistor
(damaged R1 resistor) would produce 240/2500 = 100mA, but in actual
test got very hot in a few seconds - hence indicating a short
somewhere?



Sorry, it is actually TOP209P. At the top is written K021 and at
bottom 1067 1B,

Well well well, that's a 3-terminal off-line PWM switch, as predicted. How
many windings/leads on the transformer. The typical circuit diagram in the
TOP209 datasheet shows it being used to derive a stable DC voltage via a
transformer with a bias winding. It's possible that this guy produces the
12VDC to operate the relay. A schematic would be really helpful here.

I don't quite know how to draw a schematic diagram with text, but most
connections to TOP209 have already been described:

From mains live (other connection) to pins 1,2,3,7,8 of IC 1 (TOP92P)
From transformer terminal 3 to pin 5 IC1 (TOP92P)

I can add the following:

From pin 4 IC1 (TOP92P) to capacitor C4 (positive terminal, other end
marked negative. Value is 22uF, 50V.

From pin 4 IC1 (TOP92P) to small diode D6 (Anode). D6 looks like
1N4148??
From small diode D6 (Cathode) seems to go to D5 (Anode) and positive
terminal of electrolytic capacitor C3 (16V 100uF).

The (small) transformer have 4 terminals.

Thanks for all your kind help.
Best regards,
Theo