Printer and Photocopier Troubleshooting and Repair Collection : Dead Cannon, Compaq, HP, and similar pow..  
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Dead Cannon, Compaq, HP, and similar power supplies

Apparently, these power supplies may blow their internal fuse either as a result of an overload, or possibly for no reason at all. In this case, a new fuse will be all that is needed. Of course, it's also possible that there is a fault in the power supply or in the printer which will cause the new fuse to blow but it's worth trying a new fuse before more complex troubleshooting.

(From: Jim Steel (procomputer@telisphere.com).)

Repair instructions.

The power supply is encased in a bonded 2-piece ABS plastic housing. There is a fuse inside but no way to access the fuse without splitting the case.

Splitting the case:

Unplug the power supply and secure the power supply in a utility vice. Use a short-blade utility knife or linoleum knife to slowly and carefully and cut along the seam where the 2 halves of the power supply are joined. Don't try to cut the seam all at once. Work a little at a time until the case halves can be separated.

Replacing the fuse:

On a power supply with an unsoldered fuse socket, simply replace the fuse and test the power supply. Alternately, a leaded fuse may be soldered in.

On a power supply with the fuse soldered into the fuse socket, leave the fuse in the socket and solder in a leaded fuse. (A leaded fuse has lead wires extending from each end of the fuse.)

On a power supply with a leaded fuse, unsolder the old fuse solder in a new leaded fuse.

Testing the power supply:

Ensure that the power supply and printer work before bothering to close the case.

Closing the case:

ABS plastic cement may be used to bond the power supply case halves. Alternately, electrical tape may be used to hold the case halves together.

Note: also see the chapter on Photocopiers as the operation and problems of the two types of equipment are very similar.

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