Stepper motor problem on my x-axis power feed.

[raynerd]

Hi guys, I`ve been meaning to post this for a while. I made this x-axis power feed a while back, posted about it on here and I have to say that it is possibly the best modification I have done to any of my machines.
http://madmodder.net/index.php?topic=2417.0

It has been working perfectly for some time and then I had a session where it seemed to lose all power and just generate a groaning noise. I turned it off and next time I came to the workshop it was working fine and forgotten about. Anyway, for the last week it has been doing it permanently. It is a low pitch groaning noise where the motor seems to be stalling. But the strange thing is, if you look at my motor it is fitted to the other end of the table than the handle so when you place your hand on the wheel and give it a light touch to help it around it goes around effortlessly! Just the lightest of lightest touch on the handle cures the problem, remove the helping hand and the motor groans. Even when taking a decent cut, just a light touch on the hand wheel stops the motor from stalling!

I`ve not got the money to just go and replace the drive and motor without being sure it isn`t something that can be fixed. I`ve tried two power supplies and the issue is not cured. Although I`ve played with stepper motors a few times the truth is I`m not that savvy on how they work so have no idea how to diagnose the problem.

Has anyone got any advice or suggestions? To me, it is just this bizarre behaviour of how a helping hand, literally a finger push on the hand wheel cures the problem, yet it can`t even traverse the table taking no cut without stalling on its own!

Chris

[kwackers]

Is there any chance that a chip has flung itself over and bounced in through an air vent or some such...?

You've no idea how funny that is! 

[raynerd]

Sod off Kwackers     Ken, I basically had a driver blown on me a year or so ago, I gave it to kwackers for inspection and "apparently" it was full of swarf - of course your suggestion that the issue could be the same, has made his day!     Ken, I`m just off out now to a wedding for the day but I`ll try you suggestions tomorrow and let you know how I get on. The driver is enclosed after my previous run-ins with swarf so I can`t see it being that. You said don`t blow the board, is the best way to brush it or just a close inspection and obviously carefully remove anything visable?
 Chris

[kwackers]

I'm not saying there was a lot of swarf in there, but on first inspection I thought the heatsink had melted. 

[j45on]

Would it be safe to put in a ultrasonic cleaner with distilled water ? I seem to remember you had one Chris  ( could be someone else )

[kwackers]

Removing the swarf wasn't an issue on the last one (although storing it was).

It used a A3977 driver which are fine unless you short motor outputs between opposite windings.
I've a collection of these boards and replacement chips here waiting for me to practice my surface mount chip replacement skills (which tbh are pretty poor, perhaps I should start another thread for hints and tips).