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Post by msciej on Oct 13, 2013 15:08:08 GMT -5
Guys, I was about to mod my sega mega drive PAL model 2.
I was examining the motherboard and touched the heatsink by an accident - OUCH! it was extremely hot! Is that normal? I can hold it for one, three seconds but after that its just too hot and burns. I disassembled the unit for the first time in my life so i have no idea whether this temperature is something normal or not.
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Post by msciej on Oct 15, 2013 16:49:35 GMT -5
In other words, what is the highest acceptable temperature of the voltage regulator? The heatsink burns... I am using an original powerbrick, the unit is a PAL one, MD2 VA1.
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Post by blabla on Oct 15, 2013 21:21:54 GMT -5
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Post by msciej on Oct 20, 2013 7:25:51 GMT -5
Well, it turned out that that my ORIGINAL power brick feeds my console with 15v instead of 9. Thats around 66% higher than expected, I am not sure if thats the reason for such a high temperature of the heatsink tho. I'm gonna give it a try and replace the power brick, we'll see. Of course, I could always check the voltage regulators datasheet, but it seems to be filled with too many rubbish stuff, quite unuesefull at this point. Hopefully thats the powerbrick not the regulator.
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Post by Tom Maneiro on Oct 27, 2013 17:01:55 GMT -5
Better replace the brick. 15V output for a 9V-rated brick means that it is operating way beyond spec, and it can be even a fire hazard.
The brick feeds a 7805 IC, which is a linear regulator that outputs 5V from whatever voltage you feed into it, and converts the excess voltage into heat (which is perfectly normal for those). Of course, more input voltage == more heat == BAD. 78xx regulators rarely (if ever) die, so better go and change that brick for your safety.
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Post by GiGaBiTe on Oct 28, 2013 4:52:09 GMT -5
Well, it turned out that that my ORIGINAL power brick feeds my console with 15v instead of 9. Thats around 66% higher than expected, I am not sure if thats the reason for such a high temperature of the heatsink tho. I'm gonna give it a try and replace the power brick, we'll see. Of course, I could always check the voltage regulators datasheet, but it seems to be filled with too many rubbish stuff, quite unuesefull at this point. Hopefully thats the powerbrick not the regulator. If you have a wall wart (or linear power supply to be proper) that is more than 5 years old, you should always check the voltage output before you use it. Wall warts don't have an indefinite lifetime and will eventually fall out of spec, even just sitting in a drawer. The reason they get voltage drift is because windings inside the transformer start shorting together. The more shorts there are, the more variance in voltage will be. Generally the voltage will continually rise, but in rare cases, the voltage will fall off or drop to nothing. The reason the windings short is because the output side of the transformer has extremely thin copper coils that are tightly wrapped and have an incredibly thin amount of insulation on the wire. While the transformer is active, the electromagnetic field causes the coils to vibrate and wear on the thin insulation. While the transformer is off, the pressure of the coils still causes damage to the insulation. |
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