[Ayyub2007]

Hello all,

I recently picked up a G0704 for cheap (mfg: 5/2010) and I cannot get it to turn faster than 1500rpm in high gear even if I let it warm up. If I grab the spindle while in high gear, I can virtually stop it and it blows the fuse. I can feel the controller (I think) compensating for the torque load but it still blows the fuse. I cannot stop the spindle at any speed in low range and it does not blow the fuse. The quill will get to 140-150 degrees after running for 4-5 minutes. I researched this problem and even called grizzly and the initial fix was to replace the spindle bearings. If I put the spindle back in without installing bearings (just holding it in place) I can still bind the motor in high gear so i am thinking it's not the spindle bearings. If I run the machine without the spindle in place, just turning the speed selector gears and the gear-set that would turn the spindle I can just break 1600rpm and if I shut the machine down, it will go from 1600-0rpm in less than 1 second. Is it normal for it to brake so quickly? I disassembled the motor and it looked good. The commutator was a bit dirty to I shined that up, checked the bearings and put it back together with no improvements. I checked the driver and it is outputting 96v at full throttle on low gear and 108v at full throttle on high gear. The mill has the original version motor, not the v2. When I called Grizzly back a second time to see what troubleshooting steps I could take, the answer was to just use low gear and run it until something completely fails and then I will know what part was the problem. Though I understand the logic, it would be great to service this unit before something catastrophic occurs, not to mention I lose out on some milling options due to speed reduction.

Any suggestions on where to start or what to look at would be much appreciated. Thanks for taking the time to read this post.

[coherent]

I would think it has to be either the motor itself or the controller card. I'm not an electronics engineer nor seen a schematic, but I do have one and have become pretty familiar with it. I'm sure you can test the motor, as it a fairly standard Dc motor. Both the motor and speed controller board are each $130-$140 to replace, and the only other board is about $38. Turn everything off and put it in neutral and turn the spindle by hand... it should turn freely. No tightness or rough spots. If there is it's likely spindle/bearing issues. Do the same in both high and low gear. If there is any tightness or binding, there are gear issues. If everything spins freely remove the motor. The shaft should spin freely. Run it without being connected to anything (just laying aside not connected to the plastic gear). If you have a way to check RPM it should be about 5000. Maybe less depending on the year/motor. You can try rubbing a piece of wood against the shaft to see of the motor torque slows really easily. If the motor seems fine, then my best guess is the speed controller board.
The only other possibility I can think of would be a bad connection between one these components connection wires resulting in a loss of voltage/ground somewhere.

[AVRnj]

Hello all,

I recently picked up a G0704 for cheap (mfg: 5/2010) and I cannot get it to turn faster than 1500rpm in high gear even if I let it warm up. If I grab the spindle while in high gear, I can virtually stop it and it blows the fuse. I can feel the controller (I think) compensating for the torque load but it still blows the fuse. I cannot stop the spindle at any speed in low range and it does not blow the fuse. The quill will get to 140-150 degrees after running for 4-5 minutes. I researched this problem and even called grizzly and the initial fix was to replace the spindle bearings. If I put the spindle back in without installing bearings (just holding it in place) I can still bind the motor in high gear so i am thinking it's not the spindle bearings. If I run the machine without the spindle in place, just turning the speed selector gears and the gear-set that would turn the spindle I can just break 1600rpm and if I shut the machine down, it will go from 1600-0rpm in less than 1 second. Is it normal for it to brake so quickly? I disassembled the motor and it looked good. The commutator was a bit dirty to I shined that up, checked the bearings and put it back together with no improvements. I checked the driver and it is outputting 96v at full throttle on low gear and 108v at full throttle on high gear. The mill has the original version motor, not the v2. When I called Grizzly back a second time to see what troubleshooting steps I could take, the answer was to just use low gear and run it until something completely fails and then I will know what part was the problem. Though I understand the logic, it would be great to service this unit before something catastrophic occurs, not to mention I lose out on some milling options due to speed reduction.

Any suggestions on where to start or what to look at would be much appreciated. Thanks for taking the time to read this post.

Its possible that someone messed with the pots that control speed and torque on the control board. When I tried doing this, I was having problems with the power output and was blowing fuses way too easily too. Somewhere there is a manual for a KBIC (I think) board that specifies the defaults for the pots. I put my pots back to the default, and made very slight adjustments to them one at a time until I was able to get it where I wanted. I also changed out the 10 amp fuse with a 15 amp one from radio shack. Not saying this is the problem, because the controller could be bad, or the motor too, but this is something you can certainly look into