Failed (overheated?) X2 Mini Mill

It looks like they also glazed over the surface mount chips for some reason. I can't imagine it would be one of those deals where they don't want you to see what they are, but maybe something in the masking stage just blasted over everything.

hello @Jidis, it is commonly called "conformal coating" and is typically used like a weather-proofing layer, although it is NOT that good.
It does help in staving off moisture indused corrosion for a few years.
-brino
 
hello @Jidis, it is commonly called "conformal coating" and is typically used like a weather-proofing layer, although it is NOT that good.
It does help in staving off moisture indused corrosion for a few years.
-brino
Yeah, it just seems like those procedures usually spare certain areas. This thing looks like it randomly hit stuff. In addition to the IC labels, the whole top of one of the caps is coated, but not the others.

An additional question if anybody knows- I was checking the two MOSFETs as described in LMS' "drive troubleshooting" pdf. Everything checks OK, other than the last check which reads infinity across pins 2&3 regardless of how the leads are oriented. Is a normal multimeter supposed to care about that when it's in resistance mode?

Thanks!
 
On that last check, do the two mosfets give the same result? If so then they are probably ok.
I'm not real familiar with the mosfet style controllers and would recommend sending it to olduhfguy.com for repair
I don't see anything obvious in the pictures
sorry
there is a fairly detailed troubleshooting section on his website, take a look
 
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Mark,

That board is back in now, but I believe it was the same (no continuity) on both of the MOSFETs, where there was supposed to be some in the reverse direction between 2&3 if that's correct. One of the last things I did when it was back together, coincidentally, were a couple of the checks from that olduhfguy site. I think there was no DC happening on the speed pot lines. The motor ran about as well as I guess it's supposed to on an external 12V supply, so that seems OK.

Unfortunately, the torque trimmer had no effect either, and it's one of those multi-turn things, which I rotated enough to have no idea where it once was. I think Jose Rodriguez had info on setting the lathe one, so I guess I can cross that bridge if the machine ever gets brought back to life.

This all sucks as I was finally quite happy with the adjustment of the mechanical parts and was enjoying the nice smooth belt drive mod I just finished.

Take Care
 
No voltage at the speed pot means there's a low voltage supply problem, unfortunately without a schematic diagram it would be hard
to know what to do
I think spending 50$ plus shipping would be reasonable to get it fixed
 
Mark,

Actually there was voltage at the P1,2,3 points. I'm having trouble getting good contact on this thing with a meter when it's installed, and I was in a bit of a hurry. I've got the MOSFETs, optocouplers, the original version of rectifier, and the two +/- 12V regulators on the way. I'll very carefully swap all that and check whatever else I can with a multimeter, then see what it does. Last resort, I'll see if the UHF guy will still mess with it. FWIW, this isn't a cheapness thing, but more for the experience and trying to get the machine back up as quickly as possible. I'm fortunate to have rework equipment here and understand the risks, so I'd feel kind of guilty if I didn't at least try.

Take Care

PS- That coating is a real mess. I saw other mentions of it when I looked up info on the power board. They slopped some sort of varnish all over a bunch of the parts, which makes things a bit difficult to probe (and probably remove for the surface mount stuff). I had to desolder a bunch on something one time that were actually glued down, but at least that wasn't covering all the leads.
 
OK understood, just be careful not to damage the pc board traces- those chinese boards are notorious for coming apart at the slightest touch if you
don't have the proper rework tools and a sure hand
good luck
 
GRRRRR!!! Still waiting on parts from Mouser, I figured I'd double check a couple things, and just noticed one leg of that big coil is no longer going down into the board. It's possible it popped loose while I was desoldering or messing with it, but I remember another guy online mentioning the same issue and having to unroll a bit more to get back into contact, so it's possible that heat gets them sometimes. I'll still put nice new parts on there when they get here. If all goes well and it works, I guess I'll have spares. * looking at the picture, it's got some scorching around the old joint
just be careful not to damage the pc board traces- those chinese boards are notorious for coming apart at the slightest touch if you don't have the proper rework tools and a sure hand
Yeah, this was not the most friendly thing to work on for anybody that considers it. A bunch of the leads were such a snug fit that the desoldering iron couldn't free them effectively and I still ended up with a desoldering braid for a bunch of it. Then there's the wonderful lacquer or whatever. The board has that cheap, glossy look that reminds me of Asian motherboards and PCI cards I used to get from all those "PCChips" companies. It's a shame that they've made it non-cost effective to replace at >$100. It should be in the neighborhood of twenty-five or thirty tops.

<edit> The Fonz thing makes sense now too. I probably bumped it back into contact temporarily, then it worked itself open again after a few cuts.

busted leg.JPG
 
So was that the problem after all? That's a main power filter choke
 
I replace the with better one try Amazon or eBay.
Even fix the broad you have it still a week

Dave
Hi all,

I screwed this thing up the other day and thought I fixed it, but evidently haven't. It's the Harbor Freight version (44991) with the regular cylindrical black motor.

I tried to hog too much steel a couple days ago, which caused what I thought was some sort of overheating protection. The machine was dead, but still getting power (good fuse, power light and exhaust fan active). I tried to let it cool a while, which didn't help, so I pulled the PCB from the rear box to check it (not quite as easy as it sounds). Nothing showed any obvious failure or signs of heat, and the solder joints looked OK. There was a forum post where someone had the main bridge rectifier fail, so I checked that and was getting no continuity (in circuit) on diode checks. I put in a beefier heatsinked one, but somehow the original read OK after I got it out (possibly poor probe contact when I checked it -my fault).

Anyway, all was well. It powered back up and I figured maybe that was it. I did a couple light tasks on it afterward, and went back to my steel dovetails tonight. After a couple decent cuts, it dies again. I wait a while and it still won't start. I give it a light Fonzarelli bump on the side of the control box and it starts, so I'm figuring maybe there's a bad connection I can look for later. I now think that brief rebirth was just coincidence, as it died again during the next couple cuts. No tapping in, or outside the two boxes changed anything, and the connections look solid. Unfortunately, I even pushed the new rectifier's heatsink into the nearby inductor and popped some sparks, so I'm hoping I didn't break anything new.

Any idea what this might be? The stalls and shutoff are clearly happening on strain, and seems likely to have started after that initial overload cut. It also has reached a point where nothing is even warm anymore, and I've popped the top off the motor and looked around, and don't see signs or smells of burning. During the brief times that it was running again, it seemed fine.

Sorry for all the text and any help is appreciated.

Thanks!

PS- I'm guessing that small red LED on the power board is supposed to be lit?
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