Opto-isolator problem?

[Me2]

Hello all,
I have 3 Gecko 201’s driving the 3 axis’s of my machine. After running for a couple of hours the Gecko on the Y-axis starts to growl and loose steps until it will no longer drive the stepper. I applied the magical freeze juice to the drives components to see if it was a heat related problem. When applied to the opto-isolator the stepper jumps into life and runs as sweet as a pea. I have also swapped the opto-isolators from the Y-axis drive to the Z-axis drive and the problem follows. Is this just a matter of replacing the opto (I can purchase through my local RS outlet) or is there a possible more deep seeded problem? The steppers are 2 amp 4 volt Nema 23’s, the power supply puts out 58 volts DC. The Gecko’s are mounted on a large heat sink. The opto-isolators code number appears to be A 2531, can anyone confirm this? Has anyone else experienced this problem?
Any direction or help is greatly appreciated.

Cam

[Greolt]

Cam I have a spare here if you need to keep going while getting this sorted.


Greg

[Me2]

Thanks for the offer Greg, I should be ok for the time being. Today was hot so I don't think that helped matters. I've had the same code running tonight (much cooler) without any problems. Hopefully I can just get a replacement opto and all will be well.
I need to catch up with you regarding the program from the BBQ. Ring me on my mobile to arrange a time and I'll pop over.

Cam