Re: The Resurection

----- Original Message -----
From: Paul Corner <Paul.Corner@...>
To: <CAD_CAM_EDM_DRO@onelist.com>
Sent: 30 December 1999 00:07
Subject: Re: [CAD_CAM_EDM_DRO] The Resurection


> From: Paul Corner <Paul.Corner@...>

>> From Peter Smith
Dan
why do the 0R1 ohmite resistors have to be non inductive, I have tried
to get some over here, but as yet cannot find a supply, I may have to get
some off you when I order another board.

Tim
what size motors are you using on your machine, what volts/amps are they,
mine are 2.5volt 4.5amp

Best Wishes
Peter Smith


> Hi Tim & Peter.
>
> > The 5 amp board is resurected.
> > in the morning, A steaming pot of hot coffee was pushed in my hand,
(much
> appreciated after the drive) and much mulling over of the board took
place,
> over the next six hours it was duly scoped prodded parts replaced,and
brought
> back to full working order, (miracles do happen)
>
> The component that was causing most of the trouble was the 0R1 Ohmite
resistors.
> Two of the FETs on each bridge were getting much hotter than expected. The
> stepper motors also showed some rather eratic behavior, i.e. when the step
> frequency was altered, the motors would step in the reverse direction.
> When looking at the gate pulses on the IRFZ34's at the start of each train
of HF
> pulses, there was one steched pulse. Oh how much easier it would be with a
> picture. After replacing the resistors with some vitreous enamel parts -
those
> little green ones made be Welwyn and others, the problem disapeared.
> I am at a loss to explain it - I don't usually play around with high
current
> chopper drives and big inductors.
>
> > may look for a better quality Mill to CNC retrofit, but nothing to
huge,
> There might be a small VMC a little larger than my machine coming in soon,
I'll
> keep my eyes open. ;-)
>
> Regards, Paul
>
> > Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the
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