Miscellaneous Discussions Off Topic (OT) items that really don't fit into any other Category |
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#1
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Today's random project...
I haven't been working on the 911 a lot recently, so not a ton to contribute to the Porsche-iness of the board. However, it seems like at least twice a week there's another repair/restoration/build project I have to tackle in a sisyphean effort to keep all the shit I own in working order.
Today's project was the treadmill. Believe it or not, I do actually use the damn thing. This particular machine does seem to have a design flaw, though - it blows the motor control MOSFET every 200-250 miles of use. This is a shot of the motor control board with the red arrow pointing to the problem MOSFET in question: It's become such a common issue that I actually buy the damn things in bulk: I've tried plugging the treadmill into a surge protector, unplugging it when not in use, etc. Still blows the damn MOSFET every 1-2 years. Now, replacing the MOSFET is simple enough - I have the tools and experience after all - but its a pain in the ass. To get the PCB out you have to unbolt all 6 transistors from the heat sink, clean up the thermal paste, desolder the old MOSFET, install the new, rebolt everything, and hope that your repeated soldering/desoldering doesn't lift any traces on the PCB. All this when I really just want to go for a 2-3 mile jog. Last time this happened I swore I'd modify the treadmill to make MOSFET replacement a quick-change operation if it ever happened again. Last night I did just that. I had my son make me a mounting bracket for a TO-247 socket that I got just for this project and attached it to the frame of the treadmill: I then wired the socket to the original holes in the PCB and installed the new MOSFET. Close up: Now if (when) it blows again, I remove the mounting screw, slide the old one out, new one in, reinsert the screw and the treadmill is back and running again in 2 mins. I was a tad worried during the conversion that the wire lengths would be too long and cause some weirdness, but it doesn't seem like the transistor switches fast enough for this to be an issue. I figured the frame of the treadmill would be a good enough heat sink, but did monitor temps during a test run and everything was good.
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Chris M 1985 911 Carrera with a couple cosmetic only mods 2006 E90 330i 1999 E46 328i |
#2
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I love projects like this but never seem to find the time to do them! You may also find that changing the thermal environment will have solved the issue.
Stephen Quote:
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SJK '09 Cayman S '06 C2 Cab '02 Boxster S (gone to a good home) |
#3
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Next step: water cooling...
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1986.5 928 |
#4
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Jazz is an air-cooled kinda guy...
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David D. '87 Targa - 2021 quickly disappearing... |
#5
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ed 2016 GT4 2005 Lotus Elise 1994 RX-7 R2 |
#6
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Add lightness, oh that’s how this mess started
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Karl Lucky owner of a couple of 911’s and another Porsche or two |
#7
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Brush or brushless motor?
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http://vimeo.com/29896988 “Those that can make you believe in absurdities can make you commit atrocities.” Voltaire. "There is grandeur in this view of life...." Darwin. The mountains are calling and I must go. “The earth has music for those who listen” Shakespeare. You Matter. (Until you multiply yourself times the speed of light squared. Then you Energy) “We’ve got lots of theories, we just don’t have the evidence’. |
#8
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I guess the designers never thought someone would use their products more than 6-9 months. ha! Good job, Chris and I like that your boy helped.
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We will now use the power of the Continuum Transfunctioner to banish you to Hoboken, New Jersey. BMW Spec E46 #609 |
#9
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x2
Most of this stuff seems designed for months of use only. Good work Jazz.
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78 SC, the 'Red Car' |
#10
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Quote:
Ed
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ed 2016 GT4 2005 Lotus Elise 1994 RX-7 R2 |
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