The return of the dead flatbed scanner

Step 2 Inside the case

Just a reminder first: 100/220 ac mains can be very dangerous! Oh, I think I already told so.

First thing I did was to disembowel the scanner, after all what I needed was the case with glass and cover. No electrical parts where reused. Of course you may want to save the motors, belts, screws, head parts...You know, almost everything.

Then I opted for 3 tubes (around 8 Euro each), with ballasts and starters (6/7 Euro for each set). The switch, fuse holder and mains socket I scavenged from somewhere.
For the bottom plane I used a tin sheet. This acts as a sort of mirror/diffuser for UVs.
I used also some scrap aluminum bars from kitchen furnitures, their colour in the pictures tell it. Spacers and screws as required.

Now, the pictures show the electric diagram and the interior of the UV bed.
The circuit is based on three TL5 8W wood light tubes. Each tube is powered by its own ballast and starter . The number of tubes can be increased at will. The circuit is provided with a safety fuse and a power switch. A power socket (taken from a PC power supply) complements the circuit.

All metallic parts inside that have an external metallic counterpart electrically connect to it, must be earthed i.e. connected to the ground line. This is an important safety measure: if something goes wrong and the metal inside becomes 'live' the safety switch or fuse you have in your home trips off and no one is injured. Otherwise the external metallic part may become live without anyone noticing until touched. In my case, since I used a metallic bottom and metallic spacers and screws to hold it to the case, I bolted the metallic bottom to the ground.

As I am writing I think that I should have bolted to ground the back panel which is metallic and can be reached externally as well. I'll do so.

Comments

[mrgibby]

good diagram, although where i come from green tends to mean ground, so i might've chosen a diff. color for circuit wiring. Otherwise though nice layout. Yes by all means ground every metal part that's not part of the conducting circuit.

[5Volt]

Yes, absolutely true. I actually remember seeing in South Africa a wired panel with green ground wires....I made an unfortunate choice of colour indeed ! Thanks for pointing that out. Ciao 5Volt

[spylock]

Are these the same lights that will kill algee in fish ponds?

[Foxtrot70]

Hi 5Volt, the all green wires remind me of a past employer of mine. In an attempt to "Spend a Penny to save a Pound" one of the geniuses in engineering sold the idea of changing color coded wire loom to all white with (you won't believe it) the connection info printed on both ends of the wire. One needed a magnifying glass to read this stuff 24 ga. wire makes for a very small type point regardless of font! The result of the 3 year exercise was "A Pound was spent including the Penny"! ARGH, management what would we do without them.

[jimwig]

in the usa

green is ground
white or gray is neutral
black is hot leg or #1 in multiphase
red is " " #2 " " "
blue is #3 in 120?208 multiphase
orange is # in multiphase or a high leg in a Delta
brown is # in

hey its been so long that my brain is in the wrong phase. sorry look it up and be careful.

remember that if you are not grounded shock potential is minimized or eliminated BUT trickle currents can still shock the doggy doo out of you.

stand on a dry insulator if you MUST work on a live mains situation

try not to do work without another person close by

try to learn to give CPR as coronary arrest usually occurs in electrocution

And generally if in doubt DON'T $#% with live circuits.

BE CAREFUL and BE RESPECTFUL and be SAFE