Light Engraving....

[sunil jain]

hi to every one...
Today I faced following problem with my GCC 25 watt-
First few lines are engraved dark and then suddenly engraving lightens.
optics are clean.
Any one help me on this problem.
regards.

[Viktor Voroncov]

1) Put picture of problem here
2) On which material you are engraving
3) Is this problem on different materials? Does it happened in the same place in file? on table?

[sunil jain]

1) Put picture of problem here
2) On which material you are engraving
3) Is this problem on different materials? Does it happened in the same place in file? on table?

Hi...Viktor...

1. i usually engrave on steam beech. the engraving with dark band and light band are marked.
2. the same problem is observed with acrylic and other material
3. the result varys day to day and moment to moment.
4. the engraving is darker at one moment, but at other moment engraving lightens suddenly.

regards

[Rodne Gold]

Looks like the tube is losing power - probably one of the 2 RF boards going bad , this will reduce power to 1/2 leading to the lighter engraving.
Does it get darker after going lighter or just start off dark and get lighter after a while?
Does the cutting also have issues?

I suggest opening your machine and cleaning all dust off both the laser source , fans etc and doing the same to the motherboard. A soft brush and canned air will work.

[Viktor Voroncov]

What is type of your laser tube and how long you work with this tube?

[Dee Gallo]

Have you checked whether your table is level? Could be bad focus too.

[Dan Hintz]

Try posting a pic that isn't so heavily degraded by JPEG compression... it's difficult to tell if you're getting no output on certain strips or if it's actually just a lighter engraving.

[JAIME PUJOL]

I had a similar problem lens went bad had to replace. You can tell with a eye loop if the lens has flak out.

[Viktor Voroncov]

If tube is Synrad 48 and worked at least 2 years - 99% problem in tube but easy to fix (30 minutes and $2)

[Rodne Gold]

Whats the fix Viktor?
Synrad sent me a circuit diagram of their RF board and the components needed to repair it , was quite cheap , but they also sent the instructions of how to tune the boards and that didnt look at all simple, you needed an occiliscope (sP?) and an offboard controller...

[Viktor Voroncov]

Usual problem of Synrad 48 is broken capacitors on boards inside tube. If tube is out of warranty, open it, check capacitors (marked RED CIRCLES on picture), buy from local electronic shop replacement and work.

[Rodne Gold]

Ta Viktor - looks like something else blew up on that tube judging by the scorch mark further down the cover ?

[Viktor Voroncov]

Yes, but it was another story :) Picture is just for demonstration when capacitors are.

[sunil jain]

Thanks for all of you.

1. Rodne Gold:-
it get darker few lines and lightens till last. machine cuts 3mm cast acrylic ay 2.8s/100p in enhance mode.
sometime it is light from starting and remains as it is till last point.

2. Dan Hintz:-
picture posted earlier may appear freaky because the engraved plaque is scanned.
I am again sending engraving sample 100p/12s. Earlier the same result was achieved at 100p/30s.

3. Dee Gallo:-
The level & focus of machine is perfect.

4. Viktor Voroncov:- "If tube is Synrad 48 and worked at least 2 years - 99% problem in tube but easy to fix (30 minutes and $2)"
My GCC 25W 3 year old and tube is synrad J48-2S-SGC. What is the way to fix the tube. Can it be done locally.

regards

[Rodne Gold]

I definately looks like either Viktors fix would work (worth a try) or one of the RF boards is going west. Typically , when one goes , the power drops to 1/2
Problem is , if it is a RF board and you continue to run it like that , both boards will fail.
Mail Synrad and ask em what can be wrong , they will send you repair instructions - the parts for the RF boards are cheap and can be found almost anywhere. As I said before , the tuning of the RF boards could be an issue , however I'm sure that there was a poster here that did repair their own and left em untuned and had no issues.
Call GCC as well , or mail em , they can offer you a refurbed swap out tube , you send em your old one and they send you a "new" one - its not cheap tho.

[Viktor Voroncov]

Sunil - look on my post with picture above. And do not forget post progress and results here - SHARE YOUR EXPERIENCE :)

[sunil jain]

Sunil - look on my post with picture above. And do not forget post progress and results here - SHARE YOUR EXPERIENCE :)

What is the red circled marked board called which is the RF board. We have expert electronic engineer, but is it safe to open the tube? Kindly elebrote in detail about fixing of tube.

regards

[Viktor Voroncov]

1) Detach laser tube from laser (BE SURE THAT LASER EQUIPMENT IS SWITCH OFF FROM ELECTRICITY)
2) Open upper cover on laser tube
3) USUALLY you will see broken/damaged capacitor. If you do not see - check capacitors with multimeter. Capacitors are marked with red circles on my picture.
4) Replace broken capacitor with new one (NEW CAPACITOR SCHOULD BE WITH SAME CHARACTERISTICS AS BROKEN)
5) Assemble tube and put it back to laser

If I advice you it means I did this job in past and this is not dangerous for you and tube.

[Dan Hintz]

THE NEW CAPACITOR SCHOULD HAVE THE SAME CHARACTERISTICS AS THE BROKEN ONE
I'm highlighting this one as it is very important... installing one with the wrong specs can lead to you opening up the cover again in a short period of time.

[Richard Rumancik]

. . .My GCC 25W 3 year old and tube is synrad J48-2S-SGC. . . .

If it says SGC at the end of the part number, it means that it was a special for GCC and had "heavy duty" caps installed, because GCC seemed to be having a lot of failures of the regular caps (mine included.)

The Synrad designers thought that the new component would solve the failure problem; however, some of the original problem was caused by mismatch with the supply voltage. The GCC tubes were supposed to be operated at 30VDC but many systems were shipped from GCC with the voltage at 32V which apparently stresses the caps.

If you have failed caps you are supposed to tune the RF board as Rodne indicated. But I think some people have decided to take a risk and replace caps without tuning. Sending it back to Synrad in NA costs something more than $700 to replace a board. If it is not tuned, the caps may blow again. If you can do it yourself perhaps it is a reasonable compromise (money, downtime, inconvenience).

If you go to the Synrad site you can request a schematic for the RF board. I would get current info from them as to required modification and cap specifications/part number. They have generally been good about supplying this info. (Since you should have the "improved" cap, they may simply recommend replacing with the same part number. ) Personally, I would drop the supply voltage down to 30 VDC unless the tube is marked "tuned at 32V" on it. There is a potentiometer on the power supply. Ask Synrad about this if you wish.

It is not particularly dangerous to open the metal cover to expose the RF boards. Use normal troubleshooting precautions.


. . . 4) Replace broken capacitor with new one (NEW CAPACITOR SCHOULD BE WITH SAME CHARACTERISTICS AS BROKEN) . . .

. . . unless Synrad tells you to replace it with something better. They released the cap change in about 2003 or so. Not sure if anything changed since then. I think they eventually put it into all production, not just the GCC tubes, because other OEMS were also having issues.

[sunil jain]

1) Detach laser tube from laser (BE SURE THAT LASER EQUIPMENT IS SWITCH OFF FROM ELECTRICITY)
2) Open upper cover on laser tube
3) USUALLY you will see broken/damaged capacitor. If you do not see - check capacitors with multimeter. Capacitors are marked with red circles on my picture.
4) Replace broken capacitor with new one (NEW CAPACITOR SCHOULD BE WITH SAME CHARACTERISTICS AS BROKEN)
5) Assemble tube and put it back to laser

If I advice you it means I did this job in past and this is not dangerous for you and tube.

I have not found any capacitor or circuit broken inside.
what else the problem nay be due to.

[Viktor Voroncov]

Did you test MARKED CAPACITORS WITH MULTIMETER?

[sunil jain]

Did you test MARKED CAPACITORS WITH MULTIMETER?

No, my engg. has not checked with multimeter. he suggests to replace the capacitor if it's blown off by observing.
The capacitor fitted pcb is not easy to remove, because the transistors on pcb seems to be fixed with walls of the tubes.
kindly give any suggestions for testing the capacitor
regards

[Dan Hintz]

The FETS are attached to the sides of the tube for heatsinking purposes. Search for older threads I've posted in about tube repair... films caps that have been stressed will have significant punchthrough of their film from arcing. This will reduce the capacitance significantly but until it has a complete meltdown will look normal from the outside.

[Viktor Voroncov]

Sunil, please post FULL VIEW OF YOUR TUBE WITHOUT COVER.

[sunil jain]

Sunil, please post FULL VIEW OF YOUR TUBE WITHOUT COVER.
full view of tube...

[Viktor Voroncov]

Looks like your tube is much older than 3 years :)

Do you have same detachable cover from opposite side of tube?

[sunil jain]

Looks like your tube is much older than 3 years :)

Do you have same detachable cover from opposite side of tube?

mfg date of my tube is may 07 2006 (printed on sticker)
where as i received the machine in dec. 2007.

yes, same detachable cover on opposite side.

[Viktor Voroncov]

Remove cover from opposite side and send me picture of opposite side

[Richard Rumancik]

No, my engg. has not checked with multimeter. he suggests to replace the capacitor if it's blown off by observing.
The capacitor fitted pcb is not easy to remove, because the transistors on pcb seems to be fixed with walls of the tubes.
kindly give any suggestions for testing the capacitor
regards

Sunil, the RF boards are easy to remove, are they not? But you should be able to test the caps without removing the boards. The caps we have been talking about are not electrolytic caps. Have you identified the device in question? I don't have my schematic in front of me. When they blow, yes, they usually show some kind of evidence (smoke & char) , but you might as well test them and rule it out (or not). It would be a mistake to use visual evidence alone to say they are okay.

The board with the 4 devices heatsinked to the wall is the control board. You can get a schematic for this from the Synrad manual. But you need a technician who knows what he is looking for to troubleshoot this. I don't know if Synrad will give you the actual troubleshooting procedures for the control board but it's worth a try. Look at the Series 48 manual first. You could also send them your picture. They are usually good about supporting end-users of equipment that has a Synrad tube.

I am wondering if it would be okay to disconnect input power to one RF board, and run the laser? And observe the result. (Then disconnect the other, and re-test). This might tell you something, especially if the laser goes to zero output with one of the tests. But ask Synrad first if this test is acceptable. (The 10 watt laser has one RF board; the 25 watt uses 2 boards.)

[sunil jain]

Thanks
Viktor Voroncov
Richard Rumancik

now I have assembeled the tube and will work next day.
its night here
so good night... to every one
regards

[Richard Rumancik]

So - did you draw any conclusions from your observations and measurements?

If you want to run the laser you need to do at least a crude alignment. I would not be too fussy as you can't really do productive work when it is operating like this, and I am assuming you are still in troubleshooting mode.

Further to the power supply - if your label looks like the one below ("Tested at: 32 volts") then don't change the power supply down to 30. It must be run at the voltage that it was tuned ("tested").

[sunil jain]

Thank you every one for support.
due to increase in workload i assembeld the tube. after cleaning the dust thoroughly. repairing the fans (one was jammed), doing optics alignment... the machine started consistent engraving.
Though i have to operate at low speed engraving is dark and consistent.
after couple of days completing the job, i will again put mind in tube.
regards