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