40w Synrad power loss

[Kev Williams]

My BIL has a Gravograph LS800. Other than the work area is 12 x 24 to my 24 x 24, and that his is connected via USB while mine uses a parallel cable, the machines are essentially identical 40 watt machines.

Mine is going on 11 years old, his 8 or 9 years old.

Mine still works like new (knock on my head)- in fact, after changing the mirror over the lens a few months ago, I've had to dial back the power settings on jobs I've had saved for 8 years.

About 2 months ago my BIL informs me his laser just up and started working at about half power. 90% of the work his machine does is cedar boxes. He said it was like someone flipped a switch, and half his power went away...

So I tell him it sounds like his tube may be going. Our NH rep went out to his place with his power tester, and sure enough, it's putting out 20 watts max.

The machine passed a mirror alignment test. The power supply also showed proper output at all connections at all times. No error lights on the tube or circuit boards (to the best of my knowledge).

He's been running every night since then, and nothing has changed, whatsoever. It hasn't gotten better, but it's no worse either. Other than the half output power it does everything as it should. All engraving he does- wood, Rowmark, leather- looks perfectly normal, just takes longer to do it.

Just seem funny to me that exactly half the power goes away between a power off and the next power on, and works exactly the same from then on.

Dave, Dan, Steve, any other laser guru's-- would something other than 'the tube is going out' cause this?

I'm asking because he's willing to give the $850 Ebay refill guys a chance, and we're fixing to do this pretty soon. I don't know anyone here who's gone that route, so he's going to be the guinea pig. FWIW they have a 1 year warrantee and 100% feedback, I see no reason not to try it. But if there may be some wire or connection to check, OR, some other issue not related to a 'refill' I should know and inquire about, that info would be very much appreciated!

Thanks in advance!

[Mike Null]

Kev

That is pretty much the same experience I had with both my ULS and Trotec tubes. The ULS (Synrad) deteriorated rather quickly after it hit 50% power. The ULS was in warranty and they replaced the tube in a day. The Trotec took longer (Coherent) but the result was the same. I paid a pretty hefty amount to Photovac for re-manufacturing my tube but my machine is working better than ever.

[Rodne Gold]

One of the 2 RF circuits is gonners.. the tube will fail completely shortly after that .

[Richard Rumancik]

Rodne is correct, a loss of 50% power with the Synrad points to one of the RF boards failing. But some people have successfully repaired the RF board. If someone wants to tinker, the repair can be done without sending it in. But ideally the tube is supposed to be "tuned" to the components used (which takes some special equipment and know-how). What he does depends on budget and expectations. There are some old threads on this subject and Synrad supplies the schematics involved. At one point they changed the capacitors in the RF boards to a heavier-duty type. If the cover of the Synrad tube is opened up the RF boards are immediately visible and you might see the blown capacitor right away. It is worth a look. The old threads will be helpful if he wants to try the repair himself.

[Dave Sheldrake]

Nothing I can add Kev, yup one side of the RF as Rod and Rich are saying

cheers

Dave

[Kev Williams]

Great! That's definitely a logical explanation for what it's doing! Now if only his machine wasn't 40 miles from me...

I'll run this by my BIL and our Gravo rep- He'll love tearing into it (and he's good that stuff too)

MANY thanks for the info guys! I owe ya some beer & pizza!

I'll let you know what happens---

[Chuck Stone]

It could be the RF board, but it could also be one of the capacitors on one of the RF boards, as
Richard mentioned. I went through this a couple of years ago and people here advised me to check the caps. Sure
enough, one was toasted and the other was getting there. I replaced both and got back full power.

[Kev Williams]

Update- our Gravo rep, using this thread as reference, spent some time talking to Synrad about this.

Some facts direct from Synrad:

Yes, the RF board(s) are the most likely reason for this problem.

Yes, it's likely a capacitor(s), which can be repaired on site. Otherwise, it's a send-n-wait deal.

No, running the laser in this condition will not shorten the life or harm the laser tube in any way. It will run normally, indefinitely, but at half power. The reason the tubes may seem to fail shortly after an RF board failure is simply because by the time a board fails, the tube is typically near the end of its life anyway.

So we're hoping for the easy fix. Hopefully our rep will make it out to the BIL's place this weekend...