Light Engraving....

[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.)