[Coco] DriveWire issues with Coco 1 F/285 Board

[Gene Heskett]

On Tuesday 02 July 2013 14:27:12 Luis Antoniosi (CoCoDemus) did opine:

> unfortunately the 741C is one of the few soldered IC's in my board :(
> 
Its not worth salvaging Luis, nip it off at the chip body and then you can 
unsolder it one pin at a time.  And put the next one in a gold flashed 
socket.

> On Mon, Jul 1, 2013 at 7:43 AM, Torsten Dittel <OS-9 at trs-80.cc> wrote:
> > Gene Heskett <gheskett at ...> writes:
> > > The 741C is a very slow op-amp, incapable of doing more than a low
> > > amplitude, slew rate limited triangular wave at 31.25 kikobaud.  Its
> > > full gain bandwidth is only 10Hz!
> > 
> > ...just enough for the max. 9.6 kBaud (POKE 150,1) the CoCo was
> > designed for... ;-)

Not really.  If you ever saw it on a scope, you would cringe in horror that 
it even worked.

> > > Even if you have to re-arrenge the basing,
> > > one of the op-amps in the LM35X family would be many many times more
> > > capable a device.  The LM358, in an 8 pin minidip, actually contains
> > > 2 fully compensated devices with .1 megacycle plus abilities at
> > > greatly reduced power consumption.
> > 
> > I would have to open this particular CoCo to figure out which
> > replacement IC made it in, but it was pin-compatible (and didn't
> > require further HW- changes), I guess one of these proposals here:
> > 
> > 
> > http://www.petervis.com/Education/741_Pin_Compatible_Equivalent_Op_Amp
> > s/741_ Pin_Compatible_Equivalent_Op_Amps.html
> > 
> > Regards,
> > Torsten
> > 
> > 
> > 
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > http://five.pairlist.net/mailman/listinfo/coco


Cheers, Gene
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