current meter and Estop in DSP kit

[brian257]

I bought the K40 DSP conversion kit and it comes with a digital 100mA current meter and an E-stop switch. Looking at the Rev B conversion manual the meter and E-stop switch are not in the pictures or mentioned anywhere. Can someone tell me how the meter and E-stop connect into the system or if they are even necessary. I see a stop button on the DSP controller and the LCD might show laser current so I am wondering if they are even needed. I was just about to cut the front panel and now I am at a stopping point until I get an answer.

BTW, I am using a new PWM power supply if that makes a difference. I am wondering if possibly the meter is only used on the old analog supplies?

[NickWL]

First: The STOP button. Install it! put it across the entire machine - you can't believe how many times you'll see smoke or something even nastier coming out and you DO NOT WANT to be fiddling around with pump switches, light switches, exhaust switches and all kinds of other switches - you'll just want to HIT THE BIG RED BUTTON!!
As fast as possible!!
I promise.

Second: The ammeter
Without this you'll not know whether you're driving your K40 laser tube within its tolerances. If you don't keep it below 18ma at all times you can reduce the life of the tube from a thousand or so hours to about twenty minutes. (and keep it cool while you're thinking about lifetimes - around 22 degrees C seems to be good).
Install the ammeter in series at the earthy end of the laser tube, positive terminal to the tube, negative to the PSU (and yes, a PWM PSU is more or less essential - especially if you want to get the best out of the several hundred bucks you've just spent on the upgrade).
Feed the ammeter with an isolated 5v supply (that's why you have a little black lump with six (?) legs - this isolates and regulates the voltage that powers the ammeter's circuitry). Take the input from something like your 24v PSU, don't take it from the DSP unit. Why? 'cos Marco says so and MARCO KNOWS!!

Hope this helps - and believe me, I've learned this stuff the hard way - don't feel you have to too!