Simon520
Newly Enlightened
Got a circuit board with a blown voltage regulator chip.
It's from a Pinewood Derby (Boy Scouts) digital timer that displays the order of finish and time.
It runs off 12 volts.
There is an accessory solenoid that drops the starting gate from another company that uses a 24 v power supply.
The 12 volt and 24 volt power supplies are very similar wall wart bricks. The power connector is identical.
See where I"m going here?
Looks like someone at some time plugged 24v into the 12v supply and released the smoke from Mount Fuji that makes all electrical components work. Keep the smoke in- it works. Let the smoke out- no workee. Maker of the board says it's operator error, seen it before, and a new board is $160.
The board will accept 12v of power, but the main voltage regulator quickly heats up to over 200 degrees in 3 or 4 seconds. It obviously overheated. This is the Fairchild MC78M in the middle. You can see that it got hot enough to melt the solder and delaminate the board. Digikey has those for around 60 cents.
There is another SMD component that appears to be damaged. I CAN'T IDENTIFY THIS ONE. It is an SOT-89 package with the markings F9 on one line, and 8* on the second. It is burned so that if there is another character after the 8, I can't see it.
I've checked all of the SMD device lists on the intarwebs, and nobody has an "F9" device. This appears to be a 5v voltage regulator used to supply power to the microprocessor on the board.
It's from a Pinewood Derby (Boy Scouts) digital timer that displays the order of finish and time.
It runs off 12 volts.
There is an accessory solenoid that drops the starting gate from another company that uses a 24 v power supply.
The 12 volt and 24 volt power supplies are very similar wall wart bricks. The power connector is identical.
See where I"m going here?
Looks like someone at some time plugged 24v into the 12v supply and released the smoke from Mount Fuji that makes all electrical components work. Keep the smoke in- it works. Let the smoke out- no workee. Maker of the board says it's operator error, seen it before, and a new board is $160.
The board will accept 12v of power, but the main voltage regulator quickly heats up to over 200 degrees in 3 or 4 seconds. It obviously overheated. This is the Fairchild MC78M in the middle. You can see that it got hot enough to melt the solder and delaminate the board. Digikey has those for around 60 cents.
There is another SMD component that appears to be damaged. I CAN'T IDENTIFY THIS ONE. It is an SOT-89 package with the markings F9 on one line, and 8* on the second. It is burned so that if there is another character after the 8, I can't see it.
I've checked all of the SMD device lists on the intarwebs, and nobody has an "F9" device. This appears to be a 5v voltage regulator used to supply power to the microprocessor on the board.
