Messages

5761

General Mach Discussion / Re: cnc for milling out a circuit board

« on: May 04, 2011, 02:17:22 AM »

Good work, I am pleased you got it sorted.
Thank you for sharing the links to other useful information.

Tweakie.

5762

General Mach Discussion / Re: halfmoon instead of circle

« on: May 03, 2011, 12:32:26 PM »

It is obviously not just a matter of replacing the cables, as you have just found.
Do you understand what I said in my earlier post about wiring loops and have you checked for and eliminated them ?
Have you tried bypassing the breakout board as suggested by Chris ?
Have you tried another PC to eliminate possible pp problems ?

Your earlier statement may perhaps be true "It's now left me with 2 possablities, it's either the bob or mach3". I think we all know it is not Mach3 so junk your BoB and replace it with a known good one, perhaps from CNC4PC http://www.cnc4pc.com/Store/osc/advanced_search_result.php?keywords=breakout+board&x=21&y=9
This is the direction I would take.

Tweakie.

5763

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: May 03, 2011, 11:58:24 AM »

Just a thought but there should be two 7 Amp fuses (F1 & F2) on the main board - these relate to each RF board supply.

Tweakie.

5764

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: May 03, 2011, 11:38:30 AM »

No problem using this thread - this forum is all about sharing knowledge (it is slightly Mach related so I think we can get away with it  )

As far as I can see, there are two issues regarding setting up.

1) Matching, where the power output of each board is the same and adjusted with R3 (see earlier posting).
2) Tuning, where the RF frequency of each board is the same and adjusted with C5.

An oscilloscope, preferably dual trace, would be ideal when adjusting the frequency to match both boards. I don't think Synrad specify the exact frequency although it is probably around 30Mhz so you will have to measure the good board and adjust the repaired board to match it.
Take care when making any adjustments (use non ferrous, insulated tools) as high power RF is dangerous stuff to mess with.

Tweakie.

5765

General Mach Discussion / Re: problem with the X ais

« on: May 03, 2011, 11:05:20 AM »

Hi Ennech,

Choose a value for microsteps that your machine runs smoothly with then, within motor tuning, set the steps per unit accordingly and adjust the velocity and acceleration to suit. Once this has been done there is no need to adjust microsteps again unless you think that you can improve machine performance over your earlier setting up.
Check all your wiring for poor connection, especially the axis you are having trouble with and also check the mechanicals such as loose coupler between stepper and leadscrew (check all grubscrews for tightness) etc. etc.
I know you have probably already done all this but most problems turn out to be something real simple that has just been overlooked.

Hope this helps,

Tweakie.

5766

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: May 03, 2011, 10:44:38 AM »

Do you have a problem with both RF boards ?

I am no expert here but I understand that it is quite common for one RF board to fail and the laser to continue to operate on reduced power. So far I have seen two Type 48's which have had just one RF board replaced at some time or another during their lifetime.
The MRF151 is a slightly higher gain than the MRF150 but they are essentially the same component. The mica caps will be the same value on both boards.
I am uncertain about the setting up / matching but if it is adjusted at the threshold then lasing will begin at a pulse width of 3uS +/- 0.5uS at 5kHz PRF.

Tweakie.

5767

General Mach Discussion / Re: halfmoon instead of circle

« on: May 03, 2011, 08:31:47 AM »

You have to be cunning when it comes to avoiding electrical noise problems and probably the single most common source comes from wiring loops. Loops act as antennas and pick up anything, especially if it is not required (Murphy's Law).
Avoid Earth Loops and avoid GND Loops.
Treat Earth and GND as two separate circuits.
Only terminate the shield of cables at the controller end and preferably to one single point.
The list goes on....

Tweakie.

5768

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: May 03, 2011, 08:03:21 AM »

The same here, regulated 30 Volt, 14 Amp (made in China).

Tweakie.

(Observe caution with the riser from the tube, this is in a gas seal and has to be treated with respect when un-soldering / re-soldering the cap. Also all the conductive carbon / metal deposit (from the arcing) has to be removed from all the insulated areas of the circuit board if repairing).

5769

General Mach Discussion / Re: halfmoon instead of circle

« on: May 03, 2011, 07:51:42 AM »

Where would I be getting the noise from?  The plasma's breaker is still shut off.

Electrical noise is everywhere, PC, strip lights, fan, even from your neighbours on your incoming mains supply. 

Seriously though, good routing of wires and shielded cables really pays off in the long run.

Tweakie.

5770

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: May 03, 2011, 07:30:53 AM »

Ohh dear. 

With a bit of luck it is just the 1000pF silver mica which has expired.

Here is the RF board schematic (assuming you have the version with just one single RF output transistor).

Tweakie.