AX2550 Case connected to battery -ve?

15 years 9 months ago #2426018 by Jim_MacArthur
AX2550 Case connected to battery -ve? was created by Jim_MacArthur
Hopefully this is a quick question, is it normal for the case of the AX2550 to be internally connected to battery negative?

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15 years 9 months ago #2430730 by cosma
Replied by cosma on topic Re:AX2550 Case connected to battery -ve?
Indirectly, yes.

The shell of the 15-pin connector is connected to ground and, by touching against the opening in the front bracket, will cause the case to connect to ground.

You should exercise care and never allow current to flow through the case's ground (i.e. never power the thick +batt wires without the thick ground wired connected as well). This will be changed in future revisions of the product.

Cosma

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15 years 9 months ago #2432445 by Jim_MacArthur
Replied by Jim_MacArthur on topic Re:AX2550 Case connected to battery -ve?
Thanks for your reply.

This is a bit of a problem for me, as despite my best efforts it's always possible that I could short battery positive to the chassis while connecting the batteries. Normally the chassis is isolated, so the only link to ground is through the AX2550. This would, I assume, destroy the AX2550 and potentially start a fire.

I don't think you'll recommend this course of action, but how difficult would it be to remove the connection from the 15-pin connector shell to the case? The alternative would be to mount the AX2550 onto the chassis via an isolator, but then it loses the heatsink benefits.

Thanks for any further advice you can offer.

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15 years 9 months ago #2432605 by cosma
Replied by cosma on topic Re:AX2550 Case connected to battery -ve?
The easiest would be to remove the front bracket and place a piece of plastic film slightly larger than the rectangle hole, with an opening shaped to let the 15-pin connector through. Then put the bracket back.

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Contact, when it occurs, is between the flat area of the connector and the edge of the bracket hole. An isolator shaped as described above will prevent such a connection.

Cosma

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