# Microlux 7x14 Mini Lathe Motor Controller Problems



## Lilcharlie08 (Apr 3, 2016)

Hello all, I was wondering if anyone had a Mini Lathe similar to mine? I am having a problem with the motor controller as  I blew the fuse, replaced the fuse and blew it right away again this time tripping the breaker for my basement. After further inspection I found that I had 2 of what I think are blown Rectifier Diodes. I am not sure on this and would like some input on what they are and what size they need to be as I have found a million different ones on Google. Thank you in advanced for any help I may receive.


----------



## wrmiller (Apr 3, 2016)

If the lathe is still under warranty, call Microlux and report the problem. They should replace the controller board. If it's not under warranty, there used to be a guy that advertised repair work for mini lathe and mini mill controllers. Found him once, but cannot remember what I searched for.


----------



## wrmiller (Apr 3, 2016)

I found him. Did a search for mini lathe controller and he popped up. 

http://www.ebay.com/itm/Mini-Lathe-...hash=item2330934066:m:m20mDYWDYfmgyt3u7V7tAhg


----------



## Lilcharlie08 (Apr 3, 2016)

wrmiller said:


> If the lathe is still under warranty, call Microlux and report the problem. They should replace the controller board. If it's not under warranty, there used to be a guy that advertised repair work for mini lathe and mini mill controllers. Found him once, but cannot remember what I searched for.



The lathe is not under warranty, as I bought it Friday after work off of a Individual and then this problem happened no more than a hour after getting it all set up. I do not have a problem fixing it as I can solder with no worries of destroying the board. My problem is I am not 100% sure what all the little parts are called to buy and what voltages and amps they need to be. If I can not figure something out I will send it to the guy you suggested. Just kinda wanted to get it up and running and piddle after work.


----------



## higgite (Apr 4, 2016)

This might help. It's a troubleshooting guide from LMS. It covers variable speed controllers for a couple of models of the Microlux and some others. Hopefully yours is covered.
http://littlemachineshop.com/Reference/DriveTroubleshooting.pdf

Tom


----------



## silence dogood (Apr 4, 2016)

Not having a schematic, it makes it tough for me to troubleshoot.  However, I hope this helps.  Are there two or three leads coming out on the bottom of the componant  to the circuit board?   If two, most likely a diode.  If three, most likely a power transistor, probably a FET.   Can you read the numbers?  If it says 1N---- then it's a diode.  If it says 2N--- then it's a transistor.   If you have these numbers then you may be able to order the parts.  Unfortunately,  there may be something else that is wrong that could have blown those semiconductors.


----------



## Steve Shannon (Apr 4, 2016)

It looks like D14 gave its life. R4, the large green power resistor, looks like it may have gotten hot too. D13 really got hot (in fact I can't really see its number on the silk screen layer, but I'm extrapolating). The photo is unclear there; can you get a cleaner picture so I can see the PCB and how many legs it has, or wipe that component? The rules for troubleshooting from LMS should be helpful, but it's not quite the same board.


 Steve Shannon, P.E.


----------



## Billh50 (Apr 4, 2016)

I would just buy a new board. Only because I have no idea why those parts blew. Replacing the blown parts may not be a perfect fix as something caused them to blow.


----------



## Steve Shannon (Apr 4, 2016)

Billh50 said:


> I would just buy a new board. Only because I have no idea why those parts blew. Replacing the blown parts may not be a perfect fix as something caused them to blow.


If the short was outside of the board, then the new board could be damaged in the same way.
If there was a short that was fed by the board that short must be fixed before either a repaired or replaced board is connected. Trace the output of those burned components to determine what drew so much current.
Also, I think I recall the OP saying that first a fuse on the lathe blew, then it was replaced and the next time the house breaker tripped. Did he replace the original fuse with something larger? When fuses blow it's never because too small of a fuse was specified. Replacing a fuse with a larger fuse simply makes another component into a fuse.


----------



## wrmiller (Apr 4, 2016)

Billh50 said:


> I would just buy a new board. Only because I have no idea why those parts blew. Replacing the blown parts may not be a perfect fix as something caused them to blow.



I second this suggestion. 

I also agree with Steve, in that something external may have let the factory smoke out of the controller. Verifying no shorts into and out of the controller is something I would always do when replacing a control board. This would just be SOP for me, but then I've been troubleshooting electronics since the late 60s...


----------



## Billh50 (Apr 4, 2016)

I agree about checking for problems outside of the board. But if none are found it could then be a problem in the board that is not so easily detectable without proper instruments and knowledge.


----------



## Steve Shannon (Apr 4, 2016)

Billh50 said:


> I agree about checking for problems outside of the board. But if none are found it could then be a problem in the board that is not so easily detectable without proper instruments and knowledge.


Based on the damage done to the board in the scorched area I suspect that a board replacement is needed and you're exactly right about needing knowledge and proper instruments. I don't know how much of either the OP has.


----------



## silence dogood (Apr 4, 2016)

I agree with Bill and Steve on their remarks.  Replacing the board would be the best way to go, especially since you don't have a schematic and proper test equipment.  I've worked in electronic trouble shooting over 40 years.  You learn early that when ever you replace a component,  you check the surrounding circuitry especially with high power equipment such as amps and motor controllers.   Even so after the parts have been replaced, let it run first at low power and then at normal power with test  monitoring equipment.  I apologize for not making this clearer on my previous post.


----------

