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

--- 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.