Synrad T100 tube and RF unit repair/replacemt

[Mike Lysov]

Hi guys,

It has been a long time since I posted on this forum. I was busy with relocation(done two in the last year), moving house and business from Melbourne to Brisbane first and then again moving both within Brisbane. Now it is all settled and I am glad to see you all again.

What is bad is that my LaserPro Spirit GX has stopped working. It was loosing power during long over 15-20 minutes jobs in the last 2-3 years but at least it was firing all the time. We measured output of the laser tube a year ago and it shows almost 99% of it is initial power. The laser was purchased brand new 7 years ago and I do not think I have used it from more than 20000-4000 hours.
I was thinking about some problem with overheating(even though the machine never shown any warnings about it with its inbuilt sensor for it). Then I made sure all cables are sitting tight. I found only one problem that could cause power weakness and it was a mirror for a red laser that somehow got in a path of the main beam and got cracked. I removed the mirror and hoped it would help but it did not. Actually it helped a bit making it possible to run jobs a bit longer with a higher speed as a start.
And just three days ago when I was doing a long job I noticed that my laser started skipping during cutting. I could see the beam on and off and on again during the cut. I tried to repeat the same job and it started doing the same but in slightly different places on a laser bed. I called a tech guy from a laser supplier and official distributor for CGI in Australia and he asked me to measure the laser output power before he could suggest something or even com to diagnose the problem. I could not finish checking it for two reasons. I have a huge gemtec power meter with a big probe head and I could not align the center of the probe with the beam but that was just a minor one. The major problem was that the laser was firing only for a few seconds(2-4 sec tops) and was switching off. When the tech guys came to check it the beam was not firing at all. The guy did some testing and advised that he is not sure what's wrong as LEDs on the machine and the RF unit were on as it would happen if the beam was firing. He has also tested the RF unit but he could not find anything wrong. His conclusion has been that it may be the tube, may be the RF unit or even both. He has explained how much it would cost me to repair it with Synrad and it made me cry. Especially when you do not know whether it is the tube or the RF unit.

Is there any way to isolate the problem and tell what is exactly out of order the tube or the RF unit? I do not believe they both have broken at the same time.
Even if I go with Photovac company sending them both parts for testing can cost me a few thousands in USD(in AUD it will be even 50% more) and not to mention shipping cost which will be $1200

I understand that if they are both broken there is nothing I can do apart from paying for fixing both. However it may happen that the tech guy couldn't isolate the problem.. he was in rush going to another client after me.. It may be just one of them that needs to be repaired and it even may be one of the cables used to connect the tube with the RF unit.

Any help and advise would be highly appreciated.

[Bill George]

I had a small milling machine with electronic speed control and reversing all on one board. More or less the same thing, work then not.
Removed the covers and the board, taking a couple pictures and marking wires as needed. Found one cold solder joint not even bonded to the trace, (using a magnifying glass and strong light) and with my 25 watt soldering iron and a little heat it was done. Never any problems since.

[Mike Lysov]

Thank you Bill. I wish it would be so easy with these laser parts but may be it is not a bad idea to open a RF unit and check for any component burnt.

[Rodne Gold]

"slotted" cutting is a symptom of a bad tube or a failing RF unit , there are 2 RF units , if one fails the tube generally only defaults to 1/2 power and then soon after fails completely
If the "slotted" cutting is not evident on engraving , ie it engraves at low power just fine and slots on high power , it's generally the tube...
Sorry I dont have better news for you

[Bill George]

Thank you Bill. I wish it would be so easy with these laser parts but may be it is not a bad idea to open a RF unit and check for any component burnt.

Aren't the power supply and control board external to the RF tube.

[Mike Lysov]

Aren't the power supply and control board external to the RF tube.

I do not know Bill but I can see two quite thick cables connected to my RF unit where it says "DC IN" and they are running from something that looks like a power supply to me. So I guess it is powered by external power supply.

I have also found that a blue SHT LED at the back of my tube is almost in OFF state all the time. It turns ON to Blue if I wiggle some cables on the RF unit, the tube or a bnc RF cable at the point where it connects to a laser machine main board. However it does not seem to be always depending on cables wiggling and moreover even when SHT is ON the laser still wont' fire and even LAZE LEDs on both the RF unit and at the back of the tube are not turning ON which should indicate that the tube is firing. A LED on a control panel of the machine is turning ON though when I try to fire the tube. But it looks to me that this LED is not ON on full strength of the LED. It is just not bright comparing how it was when my laser was working.

Is it possible that the power supply is dying slowly and not supplying enough power to excite the tube? Is there any way to check what is coming to the RF unit in terms of voltage in its idle state and when the tube supposed to fire and compare the results with what it should be? So basically I am asking how to measure it with a multi meter at this "DC IN" connections and what numbers I should compare the results are.

[Mike Lysov]

I will post some extra details below hopping that someone can help. I have also sent them to Synrad guys. Here is what I get:

When my laser machine starts and is initialized I can see the following LED statuses:

At the back of the tube:
RDY is ON and yellow,
SHT is usually OFF but it may turn ON(blue) eventually and either stays ON for a long time or just constantly switching ON/OFF.
If I try to fire a laser when SHT is ON on the tube it still does not want to fire and both LASE LED on the tube and the RF unit are OFF when it is supposed to fire. The machine control panel laser LED though says that the laser is firing at the same time.




At the RF unit:
INT is ON and green,
TMP is ON and green,
RDY is on and yellow.
However SHT is OFF all the time. Even when it is ON at the back of the tube it is always OFF at the RF unit.
All other LEDs are OFF at the RF unit


Synrad manual says it is a shutter fault as it it thinks it is closed. I am not sure if Synrad refers to the SHT LED at the back of the tube or at the RF unit because they are not in the same state sometimes.


No voltage fault blinking, the only thing that blinks is SHT LED on the tube when it is turning ON/OFF. Sometimes wiggling some cables can get SHT LED switch to blue or start blinking ON/OFF but I could not find that wiggling is always related to this indicator changing states.


I hope that can help to diagnose it.
The RF unit I have is FST100SAD-GCC.

[Kev Williams]

I didn't know GCC's had a shutter...

My LS900 has one, and it's quite noisy. It's a plate or disc (forget exactly at the moment) that's operated by a solenoid. When open it's parallel to the tunnel(?) and lets the beam pass. When closed, it swivels 45° and closes the tunnel. Glued to the plate/disc is a mirror, which is for the LED pointer. So the red pointer can only work when the laser can't. Whenever the laser stops or is paused or otherwise idle, the shutter closes. When the laser's ready to go, the shutter opens with a loud CLACK. It closes with a clack too, just not as loud... The whole setup is a multi-failsafe- The position of the solenoid determines if the machine will start, if it's not 'home', the machine stays paused. But if for some reason the machine thinks the shutter is open when it's not, and it runs and fires the laser, the shutter prevents the beam from entering the cabinet. One time the LED mirror came off the shutter, and it wouldn't close. Display said "shutter error" and the machine was stone cold dead. I had to take the shutter assembly apart and glue the mirror back on, it's stayed put too.. :) Every once in awhile the shutter won't open fully and I get the 'shutter error'. I've never had a shutter problem in mid-job so I'm not sure if it would shut down the machine or just stop the laser from firing.

But the LS900 was built in France, the GCC was built in Taiwan, so they're not likely much alike! However, a shutter makes sense, and for all I know mine has one. But it doesn't make a sound when it starts or stops.

But supposing your machine IS having an intermittent shutter error, like whenever the blue light blinks, the laser will likely not fire during the error- could be because blue-light-on switches the laser off, or depending on the shutter itself, it could be simply blocking the beam...

Lots of conjecture, how to proceed from this theory, not a clue I'm afraid...

Now's when we need Sheldrake! :)

[Mike Lysov]

Hi Kev,

It is not GCC that comes with a shutter it is SYNRAD Firestar RF tube installed in Spirit GX comes with it. I do not know how it flows from one component to another but it looks like the RF unit(it seems SYNRAD calling it RF power supply) either not getting a tube shutter status or just ignores it. I could get my tube starting firing and its SHT LED status now blue from a start and not blinking. However the RF power supply has its SHT LED status always OFF even when the tube is firing. The only thing that changes on the RF unit is its LASE LED is red when tube is firing. That's how it should be. The same LED on the tube is also has its LASE turn red.
However the tube does not fire all the time. In a test mode I have to press Start/Stop many times to get it firing even though sometimes it can fire from the first press. In a normal mode I could get it cutting from the first go but then it stopped firing again. Back to test mode and it can fire straight away or it can take 10-20 times pressing the Start/Stop button to get it fired.

All times before and since it broke almost a week ago it was not firing at all and SHT status on the tube was very unstable.
What I have been changed today is

1) set Tickle pulse to 5Mhz(it was set to 7 before)
2) removed a T bnc connector and connected a bnc cable directly to a BNC DB15 adapter. Not sure why they had the T connector part in a train there as it seems very pointless in a normal operation mode. It looks like you may need one for diagnostics and in case of connecting another device while all components needed to be connected in a normal way.

I do not believe that changing its tickle settings made it work in some way but may be there is a fault in a way that connects a laser main board with the RF power supply USER I/O port(that where this DB15 to BNC adapter is installed and further it uses a BNC to RCA cable to connect with a main board.

I have ordered a new BNC to RCA cable for a local electronic store today and I am going to use it instead of the original one. Something not right with the RF unit receiving commands and states of the tube and I guess this cable is responsible for getting these commands to the RF unit. The tech guy has said that it is just a regular BNC-RCA cable so it won't hurt to try to fix my laser for its cost($7).

[Mike Lysov]

We have tried to check it again with different cables and adapters. We have even tried to fire it with bypassing the laser main board. It does not work.
We have checked the voltage and it is 30V

I have taken both parts from my laser and they are ready to be packed and send to Synrad.
I hope Synrad will fix it for a reasonable price.

P.S. I have not expected them to be so heavy. The tube with an aluminium sink around is about 10 kg and the RF is about 15 kg.