RE: [CAD_CAM_EDM_DRO] L297/L298 board concern

Thanks for the good information on the Vref, I'm definitely going to look
into it.

I'm not sure if that's my problem though. I was running the motor on the
bench using a clock generator and a power supply. The motor was turning
continuously, so I don't think the Vref circuit that lowers the current
after 100ms would even kick in there.

I'm going to try lowering it anyway and see what I get, anybody got any
other suggestions?

Thanks

Gary

> -----Original Message-----
> From: JJ [mailto:jj5412@...]
> Sent: Friday, November 15, 2002 7:41 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: RE: [CAD_CAM_EDM_DRO] L297/L298 board concern
>
>
> I think the suggestion that the Vref is to high is probably correct. I
> checked my L298s yesterday after a 4 hour run, and they were
> cool, close
> to ambient. I have multiwatt-15 heatsinks clipped on with thermal
> grease, and they're in an enclosure with a 100cfm fan blowing directly
> on them.
>
> Regards,
> JJ
>
> Be Kind, Be Careful, Be Yourself
>
>
>
> > -----Original Message-----
> > From: B Snowden [mailto:bsnowde@...]
> > Sent: Friday, November 15, 2002 12:46 AM
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > Subject: Re: [CAD_CAM_EDM_DRO] L297/L298 board concern
> >
> >
> > Gary,
> >
> > I let the smoke out of one of my L298 also awhile back. Mine
> > had a heat sink on it. What I have now done, cut angle
> > aluminum to 6.75 in long. I have three L298's in a row. I
> > connected the aluminum
> > to the heat sinks of all three L298's. So what I end up with
> > is a heat sink attached to the heat sink of the three L298's.
> > When I get the board installed into a case, I plan to use
> > a fan to draw
> > air over the L298's. By adding the extra heat sink, I
> > dropped the temp from about 230+ F to around 160 - 205 F. I
> > do not know what the temp was when one of them smoked. The
> > fan should cool it even
> > more. I think you can get by without the extra heat sink,
> > but it would need to be installed in a case where a fan would
> > draw air over the L298's in a proper way. The extra heat
> > sink allows me to run
> > outside a case, and when I do install it, it should allow me
> > more margin, provided I have proper air flow.
> >
> > Bruce
> >
> >
> >
> > stirlinguy wrote:
> >
> > > Guys,
> > >
> > > I have a L297/L298 board that seems to be getting REAL hot. It's
> > > basically just the circuit from the L297 datasheet. A
> > friend of mine
> > > had the board made up with another order. I built it a few months
> > > ago, got a motor spinning (I think I was only using about
> 12v supply
> > > then), then put in on the shelf. I was playing with it today.
> > >
> > > When I run it, the L298 gets really hot. In fact, I didn't have a
> > > heatsink on it and the smoke got let out. After
> replacing the L298
> > > (and adding a heatsink), it seems to work OK, but still gets very
> > > hot. I don't want to run it too much for fear more smoke
> > may ruin my
> > > day.
> > >
> > > I am using a 24V power supply, the motor is a size 23
> that is rated
> > > for 3A, but should work fine with 2. It is stone cold
> when running
> > > at low speed from the driver. The L298 on the other hand
> could cook
> > > dinner.
> > >
> > > Anybody else have this problem? I'm not sure if there's something
> > > else screwy with the board, but the amount of heat I'm
> getting makes
> > > me wonder.
> > >
> > > Thanks in advance
> > >
> > > Gary
> > >
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> http://groups.yahoo.com/group/jobshophomeshop I consider
> this to be a
> sister site to the CCED group, as many of the same members are there,
> for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
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> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
> aol://5863:126/rec.crafts.metalworking or go thru Google.com
> to reach it if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider
> this to be a sister site to the CCED group, as many of the
> same members are there, for OT subjects, that are not allowed
> on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO
> EXCEPTIONS........
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> List Mom
> List Owner
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