Miele Electronic Programmer repair help

[Chris Holmes]

Our Dishwasher decided to self destruct a couple of weeks ago, tripping a 30A MCB as it went.

That will teach me to ignore the two times it tripped the RCD thinking they were just nucience trips !:=3D((

Anyways, opening it up what seems to have happened is that a buildup of "soap" crystals round the outlet of the Turbofan has shorted the input to the little motor/solenoid that should operate the vent openey- closey thingie.

This in turn shorted the output of a semi conductor (Triac??) on the programmer PCB and fried it. New Programmers are over =A3200.00!!

So I was going to send it off to a little man Graeme Davidson) who says he can fix lots of PCBs assumming he can get the components and the central proprietry brains haven't been fried.

But he's not answering my emails.

So I wonderered about attempting a board level repair myself (D-I-Y you see) with some help from you good folk.

However, there are some limiting factors..........

I've never worked with SMT components, though the one I suspect is a triac and the others in the immediate area have quite large connectors.

I've only got an ancient 25A Smouldering Iron.

My electronics theory is close to Zero (I can understand how an old fashioned PSU worksish), but it gets a bit squiffy beyond those complexities, I can spot a fried component when I see it, but i'd need a lot of help in determining what else may be a gonner. Having decided it was dead, i'm not sure how i'd determine what spec or values were required, and if I get through those hurdles, I don't have ready access to compnents (unless Maplins sell them) I could place small orders with CPC or Electrotech, but that gets expensive.

Should say the board appears to be completely dead (no LEDs) I have checked it's getting it's required 240V A/C, I suppose the inbuilt PSU could be fried, or could be being held down by what is wrong in the burnt-out area, or else the Microprocessor could have curled it's toes up.

Any suggestions please as to how to move forward with this (I don't want to start prodding it with my iron if it's not likely to be sucessful (and I might render the board irrepairable for someone with better knowledge / skills / equipment)), but if it's likely to be an easy fix, I will give it a go.

TIA

Chris

[Dave Plowman (News)]

To solder surface mount stuff you either need a proper workstation or a decent soldering iron with a fine tip and good skills.

If you can identify the components needed - they often have numbers on them which only mean anything to the machine supplier - Ebay is a good source for one offs. Most of the big suppliers have a minimum order charge.

[Graham.]

Will your 6kW iron be hot enough?

[Chris Holmes]

[John Rumm]

Well its not impossible...

Depending on the components in question, you can do a fair amount with a "normal" soldering iron. You may need some extra tips for it. For SMT work you will also need some desolder wick, and a tube of flux.

Have a look through this fledgling article:

has some info on surface mount work, and links to some videos that will give you a flavour.

For desoldering more complex things without much equipment, the ChipQwik alloy may be the best bet (this is basically a non-eutectic solder alloy that you apply liberally all over the connections of the thing you are removing. It mixes with the solder and then stays molten long enough to let you remove the whole device.

If you batch a CPC order for a bunch of things it ought not be too bad.

First option would be search ebay for a compatible working board!

[Dave Plowman (News)]

I usually just snip off the old component carefully using sharp small cutters and nibble at it, leaving just the end caps or legs in place. Then remove those in turn with a fine tipped iron. Of course it takes skill to just wreck the component without damaging the PCB. ;-) If a resistor or cap, I use a bit which does both at once and simply push it off with a probe once the solder has melted.

[Brian Gaff]

Not really enough info there to tell. Without the circuit and spare bets its going to be hard to tell. Now how the heck can it be a justifiable price of £200 for a board whenI'd suggest the whole machine did not cost that to start with!

Sounds like they want you to buy a new washer to me.

Brian

[Dave Plowman (News)]

It's a Miele.

[meow2222]

A 25w iron should do the job if you get a new 3mm tip for it. 2 irons are g= ood for smd removal, one is just about usable.

But you'll need to understand whats going on on the circuit and fault find,= and it doesn't sound like you have that skill. Best ask in sci.electronics= .repair.

NT

[Chris Holmes]

good for smd removal, one is just about usable.

d, and it doesn't sound like you have that skill. Best ask in sci.electroni= cs.repair.

Why two? I have enough trouble driving one these days these days between my dodgy eyes and slightly impaired fine motor control. Are you suggesting using two simultaneously?

I think the triac (if that's what it is) has the greatest number of pins, so it's not as if i'd have to unsolder a multi-multi pin device (if that's shot, i'm sure Miele wont be selling them as a separate part.

C

[Dave Plowman (News)]

As I keep on saying, don't even attempt to unsolder a multi pin device without the correct surface mount re-work station. You'll just wreck the PCB. Cut all the legs individually, remove the device then remove the pins one by one.

However, if you don't know what the suspect component is and can't identify it by the number on it, there's no point in going any further.

[meow2222]

re good for smd removal, one is just about usable.

yes, it makes removing smd parts much easier and quicker.

You need to use a multimeter to find out what's going on. Without that the = odds of a repair are small

NT

[Dave Plowman (News)]

You also need to know how to use it and have the basics of fault finding in electronics. The second bit isn't that easy or quick to learn.

[tony sayer]

You might be advised to post a couple of close up pix here where some who do know what each bit does might be able to offer some advice....

[cpvh]

I have resorted to snail mailing the guy who differs PCB repair to check he= 's still in business and interested in the job, but if I get a chafe over t= he weekend I will do a little more fault finding and also take a piccie or = two for your(Tous) further delictation.

[John Rumm]

Normally I would agree, however there is this option:

[Chris Holmes]

An update (as I know you all hang on my every word !:=3D))

Grame Davidson never got back to (I did see on Google that A Graeme Davidson has recently checked into one of Her Majesty's Holiday Camps, so perhaps that explains the lack of responce)

I decided that as I'd not found time to look at it, I'd probably never manage to find time to fix it. So I sent it off to Electroversal. Who tell me they have fixed it and it should be dispatched today or tomorrow. Hopefully i'll be back to Automatic Dishwashing by Sunday !:=3D))

Chris