Re: Miele Microwave on A55 not working


Clive Chapman
 

Sorry if this sounds a bit ‘nanny state’ and I’m teaching you to such eggs, but as an ex Merchant Navy trained Radio Officer I can confirm there are some SERIOUS life threatening voltages and systems inside even a domestic microwave oven. Please treat it with real caution. As Brent has mentioned, ensure all the capacitors are discharged before working on it.

ABSOLUTELY ensure you remove any jewellery and rings before starting. It is also good practice to do everything ‘one handed’ so if you do get a shock it doesn’t go ‘hand to hand’ across your heart. High voltages are bad news. High voltage microwaves are very bad news!

Other than that, they are remarkably simple. Working backwards there is the magnetron which generates the microwaves, a high voltage rectifier and capacitor fed by a HV transformer, some form of timer circuit that feeds the ‘low’ voltage side of the transformer (LV in this context can still be 110/240vac so even treat that side with respect), control/display circuit that tells the timer circuit what to do, and interlocks to ensure it only operates with the door closed. The remainder is ancillaries to power the turntable motor, interior lamp, etc.

If it is absolutely dead, I’d start at the mains feed input and just work logically following the circuit board and check the progress of volts, at some point early on there’ll be a break somewhere. It could be corrosion as Bill R has suggested, or possibly a blown component. One simple initial check is to have a really good look at each soldered joint on the PCB (with the power completely disconnected). It is possible a critical component has developed a dry joint - look for a slight dulling of the solder compared with other joints. Sometimes you get lucky and there’s even marked corrosion around the joint. Depending on the complexity of the PCB, number of components and your soldering skill, it can be even be worth rewhetting the joints on the main power circuit to see if that solves the problem. 

Good luck! 



Regards 
Clive
07721 894 383


From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> on behalf of CW Bill Rouse <brouse@...>
Sent: Tuesday, June 29, 2021 1:43:50 PM
To: main@AmelYachtOwners.groups.io Notification <main@amelyachtowners.groups.io>
Subject: Re: [AmelYachtOwners] Miele Microwave on A55 not working
 
It is likely something serious, but I had the same issue with my Amel installed microwave.

I opened it up getting the non-tamper screws out and discovered that when some of the internal spade connections were touched it came to life. I disconnected all of the connections, brushed-on some CorrosionX, reassembled it, and it lasted for years until we replaced it with one with more features.

I know this sounds like a commercial for CorrosionX, but it's a true life example of micro-corrosion and solutions while living aboard with salt air, and CorrosionX.

Best,

CW Bill Rouse 
Amel Owners Yacht School
+1 832-380-4970 | brouse@...
720 Winnie, Galveston Island, Texas 77550 
www.AmelOwnersYachtSchool.com 
Yacht School Calendar: www.preparetocastoff.blogspot.com/p/calendar.html


   

On Tue, Jun 29, 2021, 2:05 AM Joerg Esdorn via groups.io <jhe1313=yahoo.com@groups.io> wrote:

Our microwave went black yesterday in the middle of warming up some frozen food.  It was quite warm inside and now doesn’t show any sign of life.  Any suggestions?  


joerg esdorn
A55 #53 Kincsem
on passage to Cadiz

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