Bosch WTA3500UC/04 Auto-Cycle won't stop in delicates

[dcs]

Hi,

I have another thread going for the same dryer. I'm going to open it up this weekend to check the pulley.  As long as I'm in there, I might as well figure out why the darn thing doesn't stop when I use the Auto-Cycle in Delicates mode.

If I'm doing a regular dry (ie, I don't have the "Delicates" button pressed), the indicator lights progress through the various dryness levels (drying, damp dry, regular dry, extra dry, anticrease/end) and the dryer stops.  If I have the "Delicates" button pressed, the indicator lights stay at "drying" or "damp dry" and the dryer continues to run till I turn it off.  The clothes are well dry at this point.

I don't have a hard copy of the Use and Care manual (we bought this as a scratch 'n dent), but found an online manual for a model WTA 3510  (Axxis) that looks the same.  The manual says to clean the drum and the metal inserts of the paddles with white vinegar.  I have done that, but it didn't help.

Can anyone suggest what to look for?

  Thanks.

[Samurai Appliance Repair Man]

Otay, if you're sure those sensors in the drum are good n' clean, then we'll run some diagnostics.  I sent you the test program for this dryer via the Xdrive.  You can also download it from ratcheer.  Lemme know whatcha find. 

[dcs]

Thanks very much for the test program and for the full service training manual you put on the xdrive. That's great info to have.

I got through most of the test program cleanly until the last test which seemed to indicate I have an "open circuit or circuit resistance is too high".  I reset a connection that /might/ have been making poor contact, but didn't get a chance to test it because...ahem... how to say this....

Basically... I'm a knucklehead.

I rushed a bit too much in getting it back together (and probably had too much coffee with too little food) and wasn't paying close enough attention.  When I gave it juice, nothin' happened.  I saw a mistake and corrected it, and then only a little bit happened.  I looked around a bit and saw the awful sight of a black poof mark on a component of the controller board.

I think I blew 1 or 4 relays.  So, now the question is: 

Should I be able to replace these things?  They look like the one in the attached image (except mine have black spots on the inside of the plastic casing).  I've been hesitant to pry to hard to see if they are plug-ins.  They are made by Schrack.  3 are RP 489012.  (The fourth is RP 479012, but I can't tell yet if that one is blown).

[Samurai Appliance Repair Man]

I'm sure you can source the relays from an electronics supply shop but here's the rub:  the burnt out relays may be only part of the problem.  Parts on an electronic board can fail without any visible sign that they're bad.  So, the relays may only be part of the whole dysfunctional story.  The relays will also be much less expensive than the entire circuity board so it's worth trying to replace just the relays.  

Were you doing any disassembly with the dryer still plugged in?  

Also, this would be a good time to download the service training manual for this dryer from the Xdrive.  Log in and go to the Bosch folder.  You'll see it toward the bottom.  It's an excellent manual with color photos showing step by step disassembly. 

[dcs]

Thanks for your response.  I'll mull over what to do tonight.  Replacing just the relays would save a lot and might be interesting to try.  But if something else did fry, I won't know till after and then it's longer before we get the dryer working...

An interesting thing is that the 3 relays that are the same have big black X's penned on them (like with a Sharpie).  Since we bought this as a Scratch n' Dent, I'm wondering if the control module had work done on it before.

I'd guess soldering will be required, but jjust in case... Would you know if there's a chance these just plug in?  I don't want to pull the board out of it's frame if I don't have to.

Yes, I did unplug the machine before dissassembling.  But I plugged back in (and out again) a number of times as I tested changes.  My guess was that I did the damage by being off one prong(?) when plugging in the wire harness back into the control module.  Doh!  (Yes, I know better).

I did download the manual you put on the xdrive.  Thanks very much for that.  It's great!

[Samurai Appliance Repair Man]

I have never repaired one of these boards at the component level-- Bosch forbids this, insisting that I (as a professional servicer) replace the entire board, even if one component is bad.  If I fail to do this, and the dryer subsequently catches fire, even for a totally unrelated reason, then I am liable because I would be guilty of what's referred to as an "unauthorized field modification" of a piece of an appliance that was UL-approved, sans modification.  

Having said that, you, as the appliance owner, can do whatever you like-- it's YOUR appliance.  It's unlikely that the relay is a plug-in; most likely soldering will be required.  I've attached a how-to-solder guide.

How_to_solder_1.pdf

[dcs]

Thanks for the soldering guide.  I dunno yet what we'll do.  We discussed it over a few Smiddicks', but I'm still on the fence.  It may depend on what we can find locally.

[dcs]

I decided to get the new board to be sure (and safe).

Once I had everthing plugged back together, I repeated that last test (running the dryer with a jumper between the wires for the two drum "brushes") and it passed.

I'm getting mixed results when actually drying the clothes though.  I'll keep things as they are for now.  (DH requests I don't take anything apart again till I get caught up on the laundry).  I'll lean towards replacing the brush holders next if it's not working well enough.

Thanks for your help and the docs, Samurai.