Hey Zoltan,

I also purchased two 50 watt Synrad lasers off ebay awhile ago, both were non-working. Fortunately these lasers are not that hard to repair and I was able to fix both of them (one had a blown MRF-150 RF mosfet and the other had several fried chips on the driver board I had to replace). They now do around 62 watts each, which is pretty good. I have a spare 30V 30 amp power supply and UC-1000 controller if you happen to live near Seattle, WA

The controller is very simple..either you can do what other suggested and use two 555 timers (which is almost exactly what is in the UC-1000 btw...imagine that, two $0.99 parts from radio shack, a few resistors and knobs and it sells used on ebay for over $500!) or you can program up any 8-bit microcontroller to generate the tickle pulse for you. For example, I programmed an atmel AVR microcontroller to generate the tickle pulse and also to listen in on a z axis signal from the parallel port. If the direction bit were positive it would turn the laser on and if it was negative it would turn it off. Also, I used the counter input to register step pulses to set a power level. ie, if you sent 50 pulses with the direction bit positive it would set the laser power level to 50%. This made it very easy to interface to Mach2, although I am guessing now there is some laser support in Mach3 so this would now be a silly way of doing things?

Anyway, good luck getting it up and running, and let me know if you have any problems. There are quite a few tricks you can do if things don't seem to be working right. For one thing, the 48-5 is comprised of two identical 25 watt tubes with separate RF drivers. Thus if you have a tube that is only outputting 20 to 30 watts, it is entirely possible that one of the two tubes is not working. Since the problem is more likely in the electronics than the tube (these tubes seem to last ages), you can do some creative swapping of RF drivers to see if the other tube also outputs 20-30 watts. Then it is just a matter of fixing the bad electronics and you are good to go. Also, while testing you can BRIEFLY run the laser without water cooling, as there is a large amount of aluminum that heatsinks the tubes. What I mean is you can turn on the laser for 30 sec or so to see if you are getting output and then turn it off and let it sit for several minutes to cool down. This is not something you would want to do with a glass tube high voltage laser btw.

There is so much more I could write about these lasers, but maybe yours just works straight out of the ebay box and you don't need to know all this.

good luck!