Need help modifying my RayFine

[Walt Langhans]

Well the adventure continues...

So after having to completely re-do the optics to get the Rayfine aligned properly (thanks again for the advice on that Rich), and trying to wrap my head around why my 90 watt laser cuts slower than my 80 watt, I finally had the laser running for about a day, and now... the power supply for the tube is (insert your favorite expletive here) dead.

After looking around in the guts of the Rayfine, I was shocked to learn that the only fuse is a breaker switch.
316993

So from the wall it goes into the breaker and then from the breaker the power goes into this
316996
And I'm not quite sure what this is, so if anyone knows please tell me. Then from that, it goes to the electronics and the power supply for the tube.

My Shenhui has separate fuses (and power for that matter) for the electronics and the power supply for the tube, so I'm thinking I should install a fuse in-line between the power supply for the tube (well the new one that I need) and what ever that thing is in the above picture. I'm ASSUMING that's the correct place to put it and that a fuse similar to what I have in the Shenhui will do what I need, but I would like to here from someone who has actual electronic / electrical knowledge VS my 'this sounds like a good plan' approach.

Also the Rayfine does not have an ammeter like my Shenhui does and I would like to install one but I'm not sure where / what to wire it into so it monitors the performance of the tube.

Thanks

[Glen Monaghan]

Looks like that little box is a generic power line filter, meant to smooth out noise in the input power and, to some extent, attenuate power spikes.

As for a fuse, you should know that fuses don't really protect the electronics. Fuses are designed to stop excessive current flow before it can heat up the wiring and cause a fire. With electronics, a large current flow typically means that something (such as a power surge) has already done significant damage to the electronics resulting in a short circuit, and that damage (short circuit) is what's causing the excessive current. If you are "lucky", the circuit will fail open and no current will flown at all, thereby protecting your fuse... Your breaker switch ostensibly performs the same function as a fuse would, except that you can reset it after it trips (once you've corrected the over-current problem). Having multiple fuses or breakers to cover different parts of the machine (such as electronics and tube) may help isolate a problem to just one part of the machine.

[Rich Harman]

The ammeter is wired in series on the negative end of the tube - where the beam exits. In electronics, current is equal everywhere in a series circuit. Voltage however is 'used up' as it goes along. So that 30KV that goes into the tube is used up in the tube, the negative end is close to zero volts - that's why you put the ammeter there instead of on the positive side.

[Walt Langhans]

@ Glen - I didn't know that about fuses. I always assume there were there to fail before any damaged happened to the component. My Shenhui has 2 separate circuits, one for the electronics and one for the power supply for the tube, and this just struck me as a smart design. So when I saw the the Rayfine has only one fail point for everything (ie the breaker) I thought it would be a good idea to add a fuse before the power supply. So do you think that's not a good idea, or not really needed or what?

@ Rich - As always thanks! I assume I'm going to need a 0 - 50 mA Panel, and I've also read that I might need a shunt do you know anything them?

[Glen Monaghan]

Your call. As I mentioned, having multiple fuses or breakers to cover different parts of the machine (such as electronics and tube) may help isolate a problem to just one part of the machine, but it isn't required to have multiples and won't really provide significantly greater protection, although it does have the advantage of allowing you to use lower current-trip devices. For example, rather than relying on a single 15 amp fuse that covers all the parts and needs a large-ish current to trip, you might be able to use three 5 amp fuses or two 7 amp fuses on different parts of the circuitry and trip at a lower threshold. Limiting current to lower levels reduces chances of fire or spreading mayhem through the power connections.

[Walt Langhans]

Thanks for the advice Glen!

[Rich Harman]

I assume I'm going to need a 0 - 50 mA Panel, and I've also read that I might need a shunt do you know anything them?

A shunt is an integral part of an ammeter, it is a very low, specific, known resistance. If you get a 0-50mA ammeter then you are good to go. Sometimes people will add shunts (resistors) to meters in order to change the scale that they read.

[Walt Langhans]

If you get a 0-50mA ammeter then you are good to go.

So I won't need a shunt then?