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Bridgrport CNC Power Supply Repair Success Story

fredhh47

Aluminum
Joined
Nov 11, 2009
Location
Upstate New York
I haven't participated on this forum in a while, usually asking for assistance, but I'm back with a different story. This is just an informational post about how I managed to get my late 70's Bridgeport BOSS 6 CNC running after a recent breakdown. It might be helpful to anyone who has or knows of Bridgeport BOSS 4-5-6 CNC that has a bad logic power supply or anyone who might be considering purchasing one to use.
By and large, you could say the logic power supply is the most important part of the machine,after the individual and combined assortment of circuit boards. But,without the logic power supply, the best boards in the world will not work. No power = Brain dead. I recently came into my shop to find that a series of brief power outages and surges had killed my machine's logic power supply as surely as a bullet to the brain. I worked at repairing it for almost 3 months, enlisting several former Bridgeport techs and other electronically inclined friends, but together, we could not solve whatever was wrong with it. Finally, in a fit of desperation, I decided to go more modern and took the advice of one of my techie friends. We looked at what the logic power supply actually supplies and came up with some important facts. That 50 pound box of components supplies 5 volts at up to 20 amps, and (+)12 and (-)12 volts at much lower amperages. All of those components drawing hundreds of watts of electricity for just 3 voltages. But they are the most important 3 voltages in the entire machine because they are closely regulated. The 5 volt supply has to hold within +/- 0.2 volts for the logic boards, the two 12's have to be almost as closely controlled for what they do. After beating my head on this project for 3 months, all it took was $75 worth of off-the-shelf power supplies and a little ingenuity with the setup and I have a functioning machine again. I plan to put together a project portfolio and an article to post shortly, but in the meantime, if anyone wants the particulars, they can ask questions here or e-mail me at [email protected]. Please put CNC Repair in the subject line.

More later, friends.

Fred
 
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