View Full Version : GCC Mercury - General questions about this model for possible restoration after fire

Christian Schink
07-03-2014, 7:23 PM
Hello everyone. This is my first post here, so let me introduce myself first. I have not found an appropriate sub-forum for this, so I guess here is as good as anywhere. Anything in italics is just about me, so you can skip that entirely. In other forums I am a member of it is regarded as a good netiquette to give a brief info as to who one is before barging in and ask questions, so I guess it should be appropriate here as well.

I am a 29 year old biomedical scientist from Germany, but I have always been interested in electronics and mechanics. I was initially planning to build a smaller CNC machine when I stumbled upon laser engravers more or less by accident. Interested in that, I started working with one of the cheapest laser engravers available on Ebay about two years ago, did a few major tweaks on that machine but ran into buffer overflow problems (Software: NewlyDraw) pretty quickly. I got very helpful information from the largest German forum for laser engraving and started to post a few HOWTOs and manuals and quickly worked my way up to be a moderator of said forum
As I was really getting into the endless possibilities of laser engraving I purchased a larger Chinese, noname-model, fully DSP-controlled laser with a 30x50cm bed (12”x20”), usually referred to as “Shenhui G350”. Very satisfied with the value for money I intended to keep this machine for quite a while but someone pointed out a pretty shabby 40W GCC Spirit to me, which I took a look at and bought almost immediately. Other than complete cleaning (taking the machine apart to the last screw, machine had apparently never been cleaned) everything was good to go and the Synrad tube luckily still outputs approximately 40W. That is the machine that I am using for about three months now, other than needing the X-roller replaced everything is now as good as new again.

A few days ago I came across a listing on Ebay with someone selling a 25W GCC Laserpro Mercury which had suffered some damage from a burn in the engraving chamber. The laser was to be sold as a set with a TBH 265 LN air filter unit, which actually was the main point I was interested in the listing. I ended up buying both the laser and the air filter after having already found a prospective buyer for the laser tube should I not be able or willing to do a restoration.

I have no problems in sourcing spare parts as the local distributor of GCC parts for Germany really seems to have similar prices as can be found on Jorlink, so that is not the issue here.
I guess either the mainboard and/or the controller/LCD-Board have suffered some damage as well, which would basically render this whole project financially sustainable. Hence a short description on how the laser is behaving at the moment and questions regarding normal operation.

When the laser is powered on there is a beep, the LCD-board lights up, but there is nothing displayed. After a brief moment the Table is lowered until reaching the bottom end switch. That is it. If I try to go to the Diagnostics menu there is only a beep after powering up but no motor movement.

With my GCC Spirit both X- and Y-axes are homed after power up, but not the Z-axis. That is only the case when the rotary unit is plugged in. There the table is lowered, but then X and Y are homed. Trying to exclude a problem with the connector for the rotary unit (shorted pins) I disconnected the connector cable from the mainboard, but still the table is lowered until the limit switch is triggered. I do not get any movement for the other two motors. Also I guess I can exclude the optical sensors for both axes as at least the recieveing sensor bits show variation in resitance upon their exposition to light or darkness. Still the board they sit upon might have suffered a bit from the fire, although it looks fine to me after cleaning.

Hence, here my questions:
1.) What is the normal startup procedure of the Mercury? (Homing of X, Y, Firmware code and logo in display...)
2.) Is there any reason you can come up with that would make the unit lower the Z-axis and then stop? I have read that depending on the setup of the machine the Z-axis is also included in the initialization.

I am thinking about getting a new LCD unit (should the local distributor accept a return in case it is the mainboard after all) to see if that is the only problem regarding electronics.

Any input from you would be greatly appreciated, thanks in advance.

Rodne Gold
07-04-2014, 2:26 AM
I would check the limit switch for the Z axis (table)
Other than that , check the ribbon cable from the motherboard to head PCB

George M. Perzel
07-04-2014, 7:05 AM
On turn on, the Mercury LCD says "Initializing", shows the firmware version and the table lowers about 150 mm to insure the head does not strike anything. The head then moves from the upper left hand corner to the far right, then continues down the Y axis until it hits the limit. It then traverses the table diagonally returning to the upper left hand corner. If you need a machine manual or drawings, email me at gmperzel@rochester.rr.com.
Best Regards,

Sotos Patistas
07-04-2014, 7:43 AM
My GCC LaserPro suffered a similar anomaly with the Z axis. Turned out to be the 2 leads that go to the autofocus plunger had bare spots and were shorting, making the unit "think" that the plunger was being depressed, and the table would lower until it reached the lower limit switch.
Just a thought.
Good luck.

Christian Schink
07-04-2014, 8:02 AM
I guess the bottom limit switch for the table is fine, but I have not thought about the upper one being constantly on, hence lowering the platform would make sense. About the same reasoning is valid for the Autofocus, so I will have a look at that.

Thank you for your suggestions. I will take a look at the unit this evening.

@George: I will send you a mail in a few minutes, thanks in advance.

Tomorrow I will be away from home for a week in which I cannot work on this but will keep you updated on the progress thereafter. Right now I still hope it is a combination of problems with a limit switch and a fault display board. Unfortunately I cannot really swap parts with my Spirit which would make finding the error(s) much more easy.

Thaks again,

Mike Null
07-04-2014, 9:04 AM

Welcome to Sawmill Creek. I can't be of much help but will say I've had the pleasure of visiting your fair city while spending time in Cologne where I drank a lot of Kolsch and visited family.

I'm sure you'll find some assistance here.

Rodne Gold
07-04-2014, 9:39 AM
I'm going for the AF cable or AF pin sticking or bent..forgot that...

Christian Schink
07-04-2014, 4:22 PM
@Rodney: I think I had the AF cable removed from the small board sitting at the right end of the X-Axis, as most of the cable and Laser head had molten away anyways.

@Mike: Nice to hear. Acually I live in Königswinter, about 10km south of Bonn, but i thought that naming a city close by someone might actually recognize makes more sense here.

Looks like I cannot get any work done on the laser today, so I'll have to report back after my holidays.