Benbox Laser Machines/CO2 Lasers/3D Printers

I decided to wait on some ferules and a crimper before reassembling my printer. Also bit the bullet and ordered another card and an arduino. Today, I reassembled the thing.

• the polyfuses are OK. I checked across both legs of each fuse to ground and got 14v.
• the bed works now with the external MOSFET. I looked at the wiring diagram that I was using and realized that it didn't show 12v going into the ramps card on the bed side. So no way to tell the MOSFET on the board to open up and send voltage through to signal the external one to actuate. Ran 12v back from the external to RAMPS and the bed fired right up.
• Still no joy on the tip. Just to make sure its not the thermistor, I'm going to bypass it in the software. If that doesn't work, I'll just chalk it up to a bad board and replace it with the new one.

Best,
Jerry

Oops... Should have sent this one before the last...

OK, so...  No power out to the tip or the bed (d8 and d10) but the fan (d9) switches on when I run the preheat for either.  I have 12v from the PS into the 5A. Right now I have the other 12v into an external MOSFET and the signal for that into d8. The tip goes directly to d10 and the fan to d9. I reflashed the printer but no dice. 

(Which begs the question: do I still need power into the 11A, even with the external MOSFET.) Note that I tried this with the power and bed directly to the RAMPS and it's still acting the same way.

What about LEDs on the RAMPS board? I've got a single red, and an intemittant green.

Thanks, George. I took it apart and put it back together again and the motors are turning now. I also replaced my multimeter, so I'll check the current limit later.  I need to wait for it to warm up a bit out in the garage to see if the tip and the bed are working as they toss mintemp errors right now.  Quick question: can I put 12v from the PS directly to the bed long enough to ensure that it goes on? If I'm still having issues, I'm going to re-flash the arduino and see if that helps.

Jerry

Some time ago, the MOSFET controlling the bed on my printer stick open.  As I've been printing PLA, I didn't really need the bed, so I disconnected it and continued on my merry way. At some point, I ordered a couple of MOSFETs and another ramps board.  Fast forward to yesterday.  I'm working on a prototype touchscreen to replace the audio head in my car, and I want to print it in ABS.  So now I'm replacing the ramps card. I swapped out the card, plug by plug and have checked my wiring but there's weirdness...

Steppers on manual control from the LCD are intermittent. Sometimes they work and sometimes they don't.
Neither the bed nor the top will heat.
The LCD seems to be getting power from ramps. BUT... It's also getting power from the USB, if I connect it.

I'm getting power to the ramps card from the PS. (And my multimeter just crapped out.)

So tomorrow, I'm off to pick up a new multimeter. Any ideas what to check next? I can go back to the old card for a bit, but I am going to need the hotbed eventually.

Any suggestions greatfully accepted.

Best,
Jerry

That picture helps a lot., thanks. That's a teeny-tiny MOSFET. The ones on my printer are much bigger but, then again, I guess they handle more power.  Thanks Zax.

PWM is supported by the Nano, but older controllers that were setup for Grbl 0.8 or earlier used D12 for the laser control which means on and off only. The newer controllers use D11 so you can modulate the output but of course the laser driver must be compatible. The latest machines have a TTL output on the controller and a corresponding TTL input on the laser driver, these produce the best power control. T2Laser offers velocity mode and dithered, both of which simulate the grey scale output you can achieve with a TTL system.

If your controller and laser have 3-pin connectors (power, ground and signal) then you have TTL control. T2Laser supports TTL/PWM or non-PWM systems.

Thanks Zax!  OK, questions: 

• When you talk about the "controller," are you talking about the card on the laser as opposed to the card with the Nano on it?
• A photo of the card that I have is attached. I think that you're telling me that I have the old type, as the laser connector is two-pin?
• So, if the laser is set up for this card (two-pin), enabling PWM is not possible, and if I really want to go that route, the answer is to replace both.
• If I have to replace, I needn't go with the 5500MW.

Thanks,
Jerry

I know, right?  Of course, given my income right now, this is more-or-less what I could afford.

Thanks Zax. That helped a bit. How do I change the resolution for the circles.  Or is that too an Inkscape issue?  I'm getting lots of g-code when I thought I should get a much simpler version...  Oh, wait. I wonder if I created the paths correctly.  This would be easier in CAD, but I'm trying to use in Inkscape because of the graphic content.

Jerry