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Unread 23-09-2006, 09:13
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Al Skierkiewicz Al Skierkiewicz is offline
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AKA: Big Al WFFA 2005
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Re: victor 885 parts

Cirrus,
I believe there is only one voltage regulator, the other things you see are drive transistors for the FETs. You are correct on the the H bridge design, this is very common in motor controls. If you look closely you will also see the equalizing resistors in series with each FET. These help to equalize the current each shares with the other two in it's string. There are very low resistance so measuring them with a normal DVM won't tell you if they are shorted. The values of these resistors are about the same as the resistance of the leads on the DVM.
Remember that depending on the intial failure of the FET, other devices connected to it may also have been damaged. For instance, a short from gate to drain may have attempted to draw full motor current through the drive transistor until it failed. Power supply traces on the circuit board may also have been damaged by the excessive currents. Use a bright light and a magnifying lens when checking for damage. Post pictures and questions if you have them. I love to see stuff that is blown up.
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Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
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Storming the Tower since 1996.