GTO 52-4 vp

Hello all,
Our GTO is blowing the F7a Fuse. I know that this fuse feeds the entire safety system, and just before the fuse blows, most of the relays engage, then disengage when it blows.
Some history. I was setting up a job, and pushed the feeder stop button. The press fed the paper through and stopped as normal. Then, a couple clicks and the press went dead. The L3 fuse (to the left of the F7a fuse) was blown. I replaced the fuse, turned the press on, got a click, and every safety light on the press came on. Checking the fuses again, the F7a fuse was blown. I have disconnected the motor cable, and the brake control cable, and no difference.

Does any one know of some "common" thing that could be shorted ?
Or any other ideas ? Tomorrow, i get out the test meter and start chasing wires.
I am also learning to read German schematics...
Thanks in advance.
WR

 

Did you smell anything unusual? It's possible your front lay barrier magnet shorted out, but usually there's a distinct "electrical burn" odor. That magnet is energized by the same 110V secondary the control voltage runs off of. Hope it's that easy, you could be chasing wires for some time.

 

Thanks Junker. I didn't smell anything, but i will check it out. That magnet is under the operator side cover, correct ?

 

No, it's under the feed table, mounted on gear side of feeder. A sign that it failed would be that the press didn't leave a sheet on the feed table...but there are other possibilities regarding that statement.

 

Not to add another problem to this thread, but i have noticed that the press never leaves a sheet on the table. Doubles, missed sheets, late sheets, they all go past the front lays. I guess i need to look at this situation closer.
Thanks Junker.

 

You bet, WR, IM me if you need help.

 

On that note, by the way, disconnect the wires at the solenoid...or just one...with the power off, cap the wire(s), put in a new fuse and see if it remedies your electrical problem.

 

Spot on Junker. Thanks, you saved me hours of chasing wires.

 

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