I think this photo says more than enough.
Obviously, she's not lasing yet, but here's a little rundown of what we've done so far:
First of all we wired it up and gave it a general inspection, I was quite surprised about the state the head was in when I took the cover off. Quite clean for a tube that's been stored in a barn shed for 13 years.
The only 'problems' we ran into were quite trivial, but time-consuming. The 3-phase connection was quite straightforward, the transformer is working perfectly and we got the 'LINE' lamps to light up even before the plumbing was done.
The hosework was kind of a mess. Seems the plumbing fittings have been cut with the same tenderness as the power cable, the water lines seem to feature quick-connect and release fittings in a year long gone, but there was nothing left on some couplings but some ground brass and a 3/4" thread as the couplings were just slaughtered with an angle grinder.
After a few attempts at a make-shift hose coupling with the inlet hose, we decided to get a standard 3/4" hose barb fitting and be done with it. By 6PM the system was up for it, and able to hold the pressure. Hence the huge puddle on the floor and the reason the power supply was on a little stool, to prevent damage from any leaks or and to prevent accidental contact with leakage water.
Quick overview of the setup. The 400V-220V transformer in the back of the shot (connected to the red 16A three-phase socket), with the 265 exciter in front of it, and the 168 head to the right on the X-shaped frame.
Throwing the circuit breaker for the first time, we didn't get any power to the PSU because the PSU's breaker kept tripping. My initial suspect was the hour-counter, which was obviously installed as an 'aftermarket' add-on and might have been faulty, but the breaker kept tripping even after disconnecting the suspected culprit.
Then I found out the main power light didn't react to any change in the MASTER CONTROL switch. Either on or off, the light stayed on, sp I suspect the previous owners had bypassed the master switch for some reason. Laserwinkel didn't have any keys to the PSU, so we installed a standard ON/OFF switch which would serve the same function, but it just doesn't work and the unit is always on when the breaker's on!
I tested the switch as well as the keyswitch it replaced, and both show an open circuit in the 'OFF' position. So somewhere there's a relay that's stuck on.
Back to the problem at hand: It turned out the breakers were continuously tripping, because everything started up right at the instant the breakers were thrown, resulting in a huge inrush current on the 208V. Once the cathode filament warmed up, the breakers happily stayed on, and about 40 seconds later we got a nice illuminated 'READY' light
A quick check with the compass to be sure the magnet was working (I would't want to reduce this thing to a heap of melting stuff anytime soon!), and we both decided to go for it. And presto -- the tube lit up on the first hit of the button.
Double-checking the cooling flow, the tube itself runs fine and we now clocked about an hour of run-time at 20-30 amps on it, after a pause of about 13 years of down-time. Somehow it's quite hard to believe that the exhaust water from the main line was only lukewarm (~30C) at 30A of tube current, effectively dumping 8kW of power straight on the street. We were probably fortunate to have a cold day and almost-freezing tap water.
The WATER ON light isn't on, but I can ensure you there's water flowing through the head. Either the bulb is burnt or the water bypass valve has been bypassed just like the master switch. There was actually an air bubble locked in the cathode bell, which eventually disappeared when the tube warmed up some more.
Looking down the cathode end at the discharge. The actual plasma looks white, but there's only blue light left once it reaches the anode -- maybe there's something wrong with the krypton fill?
And here's the anode end. We decided to call it a night at about 7:30PM, and so I haven't got the chance yet to take a look at the mirrors or Brewster stems and windows. They might be squeaky clean, or they could be completely covered in dust and crud. We'll save the optics part for another episode of this installment.
Nearing the end, I did take a double-check at the tube voltage. When it's running, it's a nice and pristine 234V (at 20A IIRC), but for some reason it was only 304 Volts when the tube's off. Could it be that the capacitor in the doubling circuit is nearing the end of its life? Either that, or I somehow mis-read the 5 on my DVM for a 3. But in any case, we got a nice collection of highly excited argon and krypton ions, ready to throw some photons at the front and back mirrors for some nice laser light in the next episode!
Your local Doc Emmet Brown, signing off.
Reply With Quote
Originally Posted by Laserman532
