[Fish4Fun]

Hey Tom,

Like Forest Gump's mother said..."Stupid is as stupid does"....So here is where I am:

I am working on a new build....I have X-Y-Z Installed and ready to test....Or so I thought...got interrupted while I was wiring the steppers and left the wires to the X-Axis "uncovered"....when I go back to setting things up to test, mentally I had "finished wiring" the steppers...obviously two of the wires on the X-Axis stepper were touching and when I powered everything up U17 lit up like the 4th of July....I removed the charred bits of the IC and then de-soldered the leads. A few of the traces are toast, so I understand Channel-0 is permanently out of commission on this board...certainly not anyone's fault but my own.

I want to make sure it is OK to continue with the board using Channel-1/Channel-2/Channel-3 to drive my X/Y/Z. Assuming it is, are there any power traces I should "cut" to further Isolate Channel-0 from disrupting the functionality of the rest of the board? Should I de-solder the mosfets? I realize this is not an ideal situation, and once testing is complete and I am happy with the machine itself I plan to order another K-Step and another K-Flop dedicated for this machine, but for the short-term I want to finish testing and I would prefer to do so with the K-Step as the driver....I have "other drivers", but they don't perform nearly as well as the K-Step and it is the performance I really want to test....

Hunter

[Fish4Fun]

Just for grins and giggles here's a picture of U17:



Fish

[TomKerekes]

Yikes! Sorry to see that.

Its impossible to tell if the other channels haven't been compromised in some way as they do share some common signals and supplies. If the MosFet's gates are not driven they may turn on and short out the supply (shoot through) so they should really be removed although I suspect they are already blown open.

Regards

[Fish4Fun]

Hey Tom,

Thanks for the quick reply! So I will remove the 4 mosfets in question and give it a try, lol. I either have a functional 3 channel driver or a conversation piece destined for the recycle bin :-) As you stated, it is pretty clear from the picture that at least two of the mosfets are toast....likely all four, but removing them won't hurt anything. If the other 3 channels still function then you should be very happy with the level of channel to channel isolation you achieved, lol. I will post back with the results....

I was going to order a new K-Step & K-Flop for this machine anyway, I was just planning on moving this K-Step to my Desktop machine and using the G540 on my desktop machine for my next project....(a small lathe) ...guess my plans have changed a little, lol...will likely see my order sometime next week....

It is really hard being such an idiot.

Fish

[Fish4Fun]

OK, it would appear I have a SEMI-FUNCTIONAL 3-Axis Driver, LOL! I need a bit of information......

The Channel 1/2/3 are operating pretty much as they should EXCEPT instead of being in 16uStep/Step mode they are in 2uStep/Step mode, As this is true for all three functional channels, I assume this means that one of the traces destroyed has either "shorted" MS2 of the other three A4989 drivers to ground, or that all four A4989 drivers use a common pull-up and one of the traces destroyed is preventing the other three drivers from getting a high voltage on MS2? Is there a convenient place I might attempt to attach a "pull up" to.....for instance it appears on U17, PIN.25 there is a via to V+, and PIN.29 has a via not too far from it...should I consider putting say a 10k ohm pull-up from the via @ PIN.25 to the via @ Pin.29 to see if that helps, or should I just accept that my 3 channel driver operates in 1/2 step mode?

Thanks in advance!

Fish

[Fish4Fun]

Here is a picture....



showing the "purposed" pull-up...

Fish

[Fish4Fun]

Update....

I "cut" the trace on the back side of the PCB just after the "via" from the top side that connects to U17 Pin 29, but there is still not a "proper" pull-up on the other three A4989 Pin 29's. Since resistor array R41 has pins 1-4 connected directly to the ISO Vcc, and pins 1,3,4 all show 1k ohm from ISO Vcc to their respective side then I must assume that either R41.2 is bad, OR that there is a short to ground in one or more of the A4989 Pin 29s....In any case If I "isolate" each A4989 Pin 29 from the "bus" and connect it to the corresponding A4989 Pin 25 with a 1k pull-up then I **should** at the very least retain the current functionality of 1/2 Step mode in all three channels....but hopefully I will return 1 or more channels to 1/16 step status....I am not going to wait for a response, lol, I am well aware of the boondoggle I am creating. My time would be much better spent simply ordering another K-Step and using the Gecko's I have on hand in the interim....but I am hard headed, lol.

Fish

[Fish4Fun]

And...Tired of messing with it....Ordered a new K-Step and went ahead and ordered a dedicated K-Flop for this machine....Once you have used a machine that runs on a K-Flop you really don't want to use anything else, and the K-Step is a fine Amplifier for stepper based machines....looking forward to them coming in so I can begin testing this machine in earnest....

Thanks in Advance Tom for quick shipping!

Fish