Quoted from Per_:
After a long pinball evening my Alien playfield LCD showed red interferences (which were gone the next day) - I had to think about the quoted post. A fan could not harm, but I am also reluctant to cut a hole in the bottom (front left would fit) of my machine.
I couldn't stop thinking about the "cooling" topic. After trying a fan (see quote) I bought a W1209 (amazon.com link »). This is a really cheap temperature control switch with a temperature display and configurable on/off-values. I used it to perform some temperature measurements inside the cabinet and experienced a temperature increase of about 8 degrees (celsius, sorry) after one hour (in a fairly cold cellar). There is a remarkable heat generation difference between "stand-by" and playing the pin.
Having all the parts available I had to finish the project: With a wood hole saw (90mm) I cut a hole in the left front corner of the cabinet bottom: I leveled the pin bottom and drilled slowly from below with a heavy duty drill mounted in a (reversed) drill stand. Oddly enough nothing went wrong.
On the W1209 I replaced the relay with a power FET and added a connector for the fan plug. The necessary 12 volt power connection is available nearby at the left side of the power supply bord. The temperature sensor should be placed below the playfield, I have to try out some options. I decided to let the fan blow fresh air inside the cabinet to support the natural convection of the warm air flowing up the slanted playfield to the upper rear holes. Maybe I will try the other direction also, I have to see.
Now I can sleep well again..
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