Re: L298 goes boom ( It's Fixed!- Yeah! )

Hey Afogassa,
Man sounds like your really having trouble keeping them cool. I would
like to see a pic of your homemade heat sink when you get the time. I
have ran files (say 30 to 1 hour long) can checked the heat coming
from the homemade heatsinks I have. There hot but not untouchable.
The main ones that get REALLY hot is when I step the voltage down
from 38v using a 7812 to 7805. I guess I am at the peak of the 7812
as it says max voltage 35V but my VOM says my transformer in puting
out 38V (after the brigde and cap).

I connected the "Dreaded" switch that got me into this mess and its
working! I now have AWO feature on the 3 axis board and a switch for
it on my box :)

later
tauseef

--- In CAD_CAM_EDM_DRO@y..., "afogassa" <afogassa@y...> wrote:
> --- In CAD_CAM_EDM_DRO@y..., "tauscnc" <tauscnc@h...> wrote:
> > Hey guys,
> > well the day is almost over and I finally got my mill working!
> well,
> > 3 out of the 4 axis :) I got the stuff from mouser today and
> quickly
> > went to work. I put in the L298 and L297 into all axis and
started
> > checking the voltage switch and stuff on the camtronic board. As
I
> > was checking pin 1 on the L298, I slipped and the lead from the
VOM
> > touched pin 3 also. A little "Tick and a spark" and it was
history
> > for the Z axis L298 :( I did a quick check by plugging in the
> stepper
> > (No Power) and it was very gritty :(
> >
> > I then de-soldered the L298 from the single 4th axis, man what a
> > project. Put that into the Z axis and checked everything. Held my
> > breath and plugged it in, and a little "zap" at that L298 or so
it
> > seemed! O man! I quickly unplugged it and plugged in the stepper
to
> > see if it was gritty but to my surprise it wasn't...a good sign.
> >
> > I thought, I wondered and I asked what I got myself into :) I
> plugged
> > it in again (not knowing what to check) and nothing worked other
> then
> > the fan and the power and check LED did not come on!! After some
> > thinking I found the 7812 burned out. Back to radio shack, and I
> got
> > a new 7812 and 7805 plus 2 of there beefier heatsinks to add to
> mine
> > homemade ones. Put everything back togeher and to make this very
> long
> > story short...IT WORKS!!!!!
> >
> > Since I only bought 4 L298, I have just removed the 4th axis as I
> > really don't use it. I don't think having 4 drivers is of any use
> to
> > a hobbiest as we don't have/ can't afford 4D converting programs,
> as
> > I learn more.
> >
> > I plan to get another single unit from Dan, get one L298 from him
> to
> > fix the "4th axis" and use those 2 on the lathe. Not much for cnc
> but
> > more so I don't have to crank the handles so much :)
> >
> > It's still working, keep your fingers crossed!
> >
> > thanks for the help everyone
> > tauseef
>
> I know how you feel, after replacing my l298 i have added a digital
> termometer to the chip it self and I'm monitoring the temp on them,
> it goes as high as 120f, with 1.3amps/fase. Ihave a custom made
heat
> sink with a aluminum plate and about 90 aluminum pins about 1" long
> press fit at the aluminum plate and a big fan blowing across it.
> I think I 'll need a better heat sink with about two small fans
> direct bolted to the heat sink to keep it from over heating.
> The problem is to get a big heat sink to fit in the board, if the
> l298 were at the edge of the board it would be easyer.