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okiepiper

Bosch WTA3510 dryer won't start

21 posts in this topic

So, I've run the test programs in the "dryer training program" document I found here, with interesting results.  Indicating lights, cycle buttons, and sensor conductance all run successfully.  Pump, motor, heater, and NTCs test doesn't run.  Start light stops blinking and eventually starts blinking again, but no drum rotation or noise of any kind.    NTC R3 (which seems to be a grey not white connector) measures open, and pins 1-3 of the motor is 56ohms (1-2 and 2-3 are ~26 ohms).  Is the open thermistor enough to prevent the test program from running?  Also, I thought that motors usually failed as a short circuit rather than an increase in resistance???  Thoughts??

 

Thanks in advance!!!

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Need appliance parts? Call 877-803-7957 now!

Control module is ok if you can access diagnostic test for leds.  As long as drive belt is tight and intact and door switch is ok, not being able to run motor or heater test could indicate a bad power module.

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Thanks!  I'll check that! :-)

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Affirmative Brother okie.  Be sure to research part using entire model number.

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Travelling?

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OK.  Measured voltage out for motor (~25VAC) and one heater for good measure (0V i.e. nada).  Looks like a power module... Hate to spend $300, but I guess that isn't too bad for a 10 year old dryer...

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You'll thank us in the morning.   :yes:

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I thank both of you now and in the morning!  Doumo arigatou gozaimasu!

 

 

You'll thank us in the morning.   :yes:

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In the words of Pooh, oh bother!  Swapped the power supply board - nada.  Thought maybe it was just the motor- not!  Possible that the new board is DOA?  Dryer model is WTA3510US/10, which corresponds to #265677.  Any additional insights?  Thanks in advance!

 

Chris

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Were you able to try diagnostic routine again, if so any different results or faults?  I'll probe Bosch's netheregions for further info.

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Same results - the routine that is supposed to turn the drum doesn't.  Kinda weird actually.  If I do a time dry (air or heat) the timer counts down, but no movement.  Is the "dryer on" signal send from another board to the power module then to the motor?  Or is that go signal generated on the power module?  Trying to figure out if there is another place I can probe with a voltmeter.  As an aside, there isn't a hidden contact that requires all the panels to be attached before the dryer will turn, is there?  Seems like shouldn't be so difficult - Just a couple of boards, fuses, and a motor...  Thanks again!

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NTC R3 should have resistance of 9-11k ohms as well as NTC R4 which measures temp of air current in bottom front of dryer.  NTC R2 above heater should measure 18-22k ohms.  The B9 thermal cutout on heater should have a red reset button.  Push that button. if it clicks reassemble and fire that sucker up!

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Thanks PDuff!  I will check resistances tonight... I already tried the red button - no clicky there, but I will give the thermistors/thermocouples another look... :thanks:

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Ran diagnostics again for confirmation - identical responses with both the new and old boards = no drum rotation and no heat.  R3 (dryer door) ~ 16k, R2 (heater) ~27k - dryer is in the cool garage, so I'm not that surprised that the resistance is higher than the spec.  Can't find R4 on the schematics...  One thing I did notice is that if I rotate the auto-cycle knob to damp dry, the number 16 appears on the display.  Can't find any reference to "damp dry" being a test, so I don't know what I have in that number...  Beer:30...

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Resolution....  Door contact switch was the problem!  Advice from the novice - don't be fooled by the timer countdown or the little blinking dot in the timer window.  Somehow, the part can fail in such a way that the dryer won't turn, but some of the electronics thinks it's OK.  Lesson learned! :tongue:



PS  Thanks again for all the help folks - it is truly appreciated!!!

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Sho nuff good to know, buddy-row!  For your contribution to the borg-like wisdom that is Appliantology, you have earned a free six month extension to your Apprenticeship.  

 

Kanpai!   :samurai:

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I'm not worthy....  I'm not worthy!!!  But, very cool - thank you!!!  :rocker:

 

Sho nuff good to know, buddy-row!  For your contribution to the borg-like wisdom that is Appliantology, you have earned a free six month extension to your Apprenticeship.  

 

Kanpai!   :samurai:

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Oh, but I disagree-- you ARE worthy, my fine, young Apprentice.  Why?  Because you FIXED your dryer!  The proof is in the fix.   :woohoo:

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