Hello everyone,
I've just bought my second F-1X preamp and it's the first version with the red buttons. The preamp is currently on 100 VAC and I'd like to switch it to 230V (Europe). Only, this version doesn't have the moving jumpers inside the unit. How can I change its voltage? Thanks to all
Best Regards

These are the posted "jumper" instructions being referred to...

http://www.alembicguitars.net/support/SVC_F1X_voltage.html

I've never opened my red-knob F-1X to see, (and wouldn't likely know what I was looking at if I did...) so no help, but the Wire Wizards will probably be able to sort this one out for you easily.

If one of you can post a picture of the transformer and surrounding area I might be able to get answer out this weekend.  Thanks

I can open mine up if necessary... it means I'd hafta' un-rack it... if the OP has easier access to theirs that'd be better. On the other hand, I always wondered if my serial number was inside or under the sheet metal...? It isn't stamped or printed where it says serial number, just blank. It is a Santa Rosa-made unit. (doesn't matter, I just gig with it) It does advise 117v on the back panel.

Finally, i've managed to change the voltage by changing 3 little wire which are supposed to be like the moving jumpers. It's only 4 solderings to move. So in conclusions, Old F-1X haven't moving jumpers but have an equivalent system with these 3 wires. Thanks for all guys

Congratulations, glad you found a solution.  Can you post a marked up labeled photo so others can see what you did?  Thanks!