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Repairing an R172 OCP fire

MarkandCath

New Member
Joined
Oct 6, 2019
Messages
2
Location
Powys, UK
Car
2012 SLK R172
Like more than a few others my OCP board has gone pop and started to smoke. The component that fails is the common mode choke on the voltage input and although it look dramatic it is a very simple fix. Sadly this tiny choke is protected only by F18 a 7.5A fuse and when this choke fails (the windings short) it is always going to burnt before F18 finally blows.

The problem is identifying the component. The damaged one is far to far gone to read the markings off and the later revised boards have the coils covered in a conformal coating so again you can't read it. Does anyone know what the value of this coil is by any chance?

For those than haven't seen the fireworks the pictures are below. As you can see after the clean up we have mild surface damage to the PCB from the heat and a bit of damaged track but nothing to worry about.


OCP damage.jpg OCP before.jpg
 
Not sure if this board is common to other Mercs but, if not, then you may have a bigger audience over at SLKWorld...
Russ
 
Hi RussJ, I already posted over there and they are unsure. Just reaching out as wide as possible to find the answer.

When we have sorted this I will post a guide because the part is £10 at most and Mercedes want over £1,000 for a new board.
 
Can't you find someone with an original board where you could remove it and read the component details?
 

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