GCC Synrad Laser Heat Failure and Fix

[Martin Reynolds]

Hot day, heavy laser work going on (1/4" acrylic which is hefty for a 30W laser).

Rapid beeps - "laser thermal error". Machine does not want to cut, so I recycled it.

Laser now cuts at half power for 2 mins, then drops back to marking only.

So I decided to take it apart and see what was up.

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A coil had overheated and fallen out of its PCB location. I soldered it back in, and touched up the ugly-looking solder on its twin. Laser is now, at least, back to full power. This repair does require a really good soldering iron as the PCB is thick copper and the coil is hefty. And remember, these things are dangerous. I have more photos of the RF board if anyone wants to see them. BTW, that transistor is $65.

[Rodne Gold]

Thats great , would have probably cost you $1500 if you had to send the source in.....

[Scott Challoner]

You might want to shoot that picture over to Synrad. I doubt they do their own PCB manufacturing, but they may want to know they have solder joints failing in the field. It's difficult to solder large components like that that are essentially just big heatsinks.

[Martin Reynolds]

You might want to shoot that picture over to Synrad. I doubt they do their own PCB manufacturing, but they may want to know they have solder joints failing in the field. It's difficult to solder large components like that that are essentially just big heatsinks.

I asked them, they said that they have never seen such a failure and said that I might still have problems, because there could be some other problem causing the laser to overheat. Once I finish the realignment - the first mirror, mounted to the laser output - was not really screwed tight to the mounting plate - it will be back to full time work and we'll see how my fix survives.

Also, I have to go through GCC for service - no terrible thing, because GCC has them available for recycling through the field. My local rep is really good, I can usually drive down and get pretty much anything for the machine.

These are fascinating devices - that's basically a super high power RF amplifier pushing 300W or thereabouts. Compare that to a glass laser, where the energy comes from a high voltage discharge, more like a neon tube.

[George Carlson]

You can tell by the color of the varnish on the coil that it has been operating fairly hot. If solder joints are held at high temperatures for long times, the solder crystalized and turned gray. It eventually crumbles. In your case, it was probably in that condition for quite some time, the high use caused the poor solder connection to get hot enough to melt and let the coil fall out. This was quite a problem in the power supplies on the old TV sets. The power resistors had long leads to prevent it, but eventually the solder joint would fail. It this happens again, get some good solder flux and reflow all the solder joints you can. If one joint is failing, chances are there will be others.

[Martin Reynolds]

You can tell by the color of the varnish on the coil that it has been operating fairly hot. If solder joints are held at high temperatures for long times, the solder crystalized and turned gray. It eventually crumbles. In your case, it was probably in that condition for quite some time, the high use caused the poor solder connection to get hot enough to melt and let the coil fall out. This was quite a problem in the power supplies on the old TV sets. The power resistors had long leads to prevent it, but eventually the solder joint would fail. It this happens again, get some good solder flux and reflow all the solder joints you can. If one joint is failing, chances are there will be others.There were a few other dodgy looking joints, so I refreshed those as well (after sucking out the old solder).The laser is now working much, much better. It is clear now that it has been deteriorating over the last 6 months.

[Scott Challoner]

Look on the board for silkscreen that says "RoHS" or "Lead Free". If it's there, then was manufactured using lead free solder and you should use lead free solder when you touch up the joints. It will require a little more heat.

[Martin Reynolds]

Look on the board for silkscreen that says "RoHS" or "Lead Free". If it's there, then was manufactured using lead free solder and you should use lead free solder when you touch up the joints. It will require a little more heat.

It is a lead free assembly. Just the coil itself, and the big pads on the PCB, were a challenge. It took a lot of heat to do this soldering, on top of the lead free. I have a higher-end Metcal and used a big bit, and it was challenged. Without enough power, you end up heating large areas of the board.

(BTW for those of you into soldering, you really have to get a Metcal or JBC. My favorite is the JBC with the small handpiece).

[Scott Challoner]

You're a better man then I Martin. I would probably have lifted pads all over the place. Then I would have to sneak back into the last CEM I worked for and begged one of the repair people to fix it.:D
I was with Plexus for many years here in Neenah, and I know they had a plant in Fremont. Did you happen to spend any time there?

[Martin Reynolds]

Never been there, but I do drive past the plant occasionally. It is right close to Solyndra, famous solar bankruptcy company. And a bit further down the road is Tesla, living in the old GM-Toyota plant.

On this laser I was lucky. The parts did not need to be pulled, and I didn't even have to remove the board. I'd say, if your laser fails, it deserves a look inside. I've attached a larger pic of what a Firestar looks like.

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[Kim Vellore]

Martin, Thanks for posting the pictures and your experience. Now I would open up the laser next time I have a fault to look for anything obvious. I was under the impression there is a sticker seal which voids swap option if customer opens the laser head. Might even be worth replacing the 4 transistors if the power goes down and no obvious faults can be detected. Thanks Kim

[AL Ursich]

Worth a mention since others down the line might search this thread. Electrolytic Capacitors are something that you want to watch for too... Any bulging of the end caps.... If you search out "Bad Caps" for a story of a stolen capacitor formula that they did not get correct. Caused Bulging and exploding Caps for YEARS.... This all happened almost 10 years ago and provided me with tons of overtime working at a Sony Service Center pulling and replacing known bad caps in 17 and 19 inch CRT Monitors.... I am showing my age.... But Caps have been pointed out in MANY of the Laser Troubleshooting Post of the past.

Good Job !!!!

AL

[Rodne Gold]

When one of my synrads 48 series blew a RF board , synrad actually sent me comprehensive instructions on repairing it , I did the repair but it failed quite regularily every 3-6 months after that , the issue was that I did not have the equipment to "tune" the RF boards after repairing (needed a offboard laser power controller and an oscilliscope)..was still a better bet spending a few $ and an hour re doing the repair than sending it from South Africa to Taiwan (GCC "own" the tube , not you) and possibly from there to the US.

I doubt that would be an issue with just resoldering the coil , but I do agree , if you have an oldish machine or tube , it's worth having a look and attempting a fix before the uber expensive "send it in to the agents for reconditioning" , if your fix doesn't work , well then it's time to do so...

[Martin Reynolds]

Worth a mention since others down the line might search this thread. Electrolytic Capacitors are something that you want to watch for too... Any bulging of the end caps.... If you search out "Bad Caps" for a story of a stolen capacitor formula that they did not get correct. Caused Bulging and exploding Caps for YEARS.... This all happened almost 10 years ago and provided me with tons of overtime working at a Sony Service Center pulling and replacing known bad caps in 17 and 19 inch CRT Monitors.... I am showing my age.... But Caps have been pointed out in MANY of the Laser Troubleshooting Post of the past.

Good Job !!!!

AL

Good point, Al. I did inspect my caps and was pleased (and maybe a bit surprised, because of the hot environment) to find no bulging whatsoever.

For those not familiar with the issue, over time electrolytic capacitors (the tubular ones in a plastic sleeve) build excess pressure and slowly vent their contents. If they overheat, they actually pop a dome shape into the top of the can, which has a cross carved into it to make the expansion easy. Caps with domes have to be replaced.

[Martin Reynolds]

When one of my synrads 48 series blew a RF board , synrad actually sent me comprehensive instructions on repairing it , I did the repair but it failed quite regularily every 3-6 months after that , the issue was that I did not have the equipment to "tune" the RF boards after repairing (needed a offboard laser power controller and an oscilliscope)..was still a better bet spending a few $ and an hour re doing the repair than sending it from South Africa to Taiwan (GCC "own" the tube , not you) and possibly from there to the US.

I doubt that would be an issue with just resoldering the coil , but I do agree , if you have an oldish machine or tube , it's worth having a look and attempting a fix before the uber expensive "send it in to the agents for reconditioning" , if your fix doesn't work , well then it's time to do so...

Rodne, for something like that I would be inclined to fire up the laser without the covers (extreme caution required, the RF will cook your eyeballs if the laser does not get you) and monitor the power with one of those plug in power things. When the thing is in tune, I would expect a dip in line power and a max on the laser output. Not as precise as the scope, but probably good enough.