E's on mA meter

[AndyKunz]

When operating my laser (60W) I notice that the mA meter shows E's as the value instead of a number.

http://www.lightobject.com/3-digit-Mini ... -P457.aspx

When I use the meter standalone on a bench supply the mA reads properly (and pretty accurately, too).

I have tried reversing the input leads, but I still see E's, even with the power dialed way down.

I suppose this could be due to the PWM, because the current will be instantaneously high (full power, low duty) and there is no filter to smooth it out for the meter to use as an average.

Any other ideas? Solutions in use?

Thanks.

Andy

[Tech_Marco]

Make sure to leave the meter away from the HV cable. When it show 'EE', it means over current. High electromagnetic field is strong enogh to cause overload

Marco

[itsmillertime]

Hi Andy I have the same problem. What did you find your solution was please?

Marco, do you really think it's just a case of screening the meter from the HV cable?

Thanks Marco and Andy

[AndyKunz]

I changed to an analog meter. Marco sells them too.

Andy

[itsmillertime]

I changed to an analog meter. Marco sells them too.

Andy

Hi Andy,

Really appreciate the reply especially since your post was so long ago! Did you find that it was simply HV interference? i.e as soon as you put an analogue meter in it read correctly?

I guess I'm just worried that right now my tube is passing more current than it should rather than perhaps just 'noise' from the HV power supply and line. But it does seem to be operating fine whilst engraving.

Thanks so much again.

Andy

[AndyKunz]

I didn't have a totally isolated supply. When I ran it off a battery (fully isolated) it worked fine.

Andy

[itsmillertime]

Thanks again for your reply andy it's saved me a lot of heartache. Cheers Andy