Film-Tech Forum ARCHIVE: Mod 2C Blown Fuse

This is topic Mod 2C Blown Fuse in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Don Furr (Member # 1469) on 06-14-2008, 07:19 PM:

After powering up my sound rack I noticed no lights on the front of my Mod2C processor. I found the 4 amp slo-blow fuse (20 amp DC positive voltage) had opened up.
This is the first fuse the PS has ever lost in all these years. Should I be looking for another problem or was it just "it's time" to give up the ghost?

Posted by Gordon McLeod (Member # 33) on 06-14-2008, 08:02 PM:

See if it blows again and then try removing a card at a time
Sometimes one of the regulators on a specific board has failed

Posted by Louis Bornwasser (Member # 3063) on 06-14-2008, 08:17 PM:

"Sometimes a blown fuse is only just a blown fuse!" with apologies to Freud. Louis

Posted by Don Furr (Member # 1469) on 06-15-2008, 03:24 PM:

Well since my first post I've discovered that the "Format" card is causing the fuse to blow. The rest of the cards have no effect.
Any idea about the possible causes on the Format card?

Posted by Gordon McLeod (Member # 33) on 06-15-2008, 03:37 PM:

probably the positive voltage regulator or a shorted opamp

Posted by Don Furr (Member # 1469) on 06-19-2008, 05:23 PM:

As a follow up to this problem with the blown +20 vdc fuse....I discovered that the fuse was blowing with the PS removed from the main frame. I'm taking the PS up to Smart Devices to pick up a rebuilt PS tomorrow morning.
Case solved.....Bad Power Supply.

Posted by Mark Gulbrandsen (Member # 72) on 06-19-2008, 07:29 PM:

These supply failures are pretty common. I can almost guarantee they will find a shorted bridge rectifier. A local chain that fortunately I don't have to service has these processors all over and the local tech usually finds a shorted bridge.

Mark

Posted by Don Furr (Member # 1469) on 06-19-2008, 08:29 PM:

Yeah Mark I think you're correct and that's the same thing the tech at Smart indicated on the phone today. That supply is at least 12 year old and this is the first trouble I've had with it.