Re: PlasmaSonic SSTC Boards - Mistake Found ! ! !

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>


Steve,

Yes, (as with my board), the IC will not work if that pin is tied to +V.
Although it will work unconnected, it should be connected to the chip's
internal Vref which is
5.0V  Try to connect it to the IC's Vref.

Dan



 > Hey Dan,
 >
 > i also made that mistake with my audio SSTC board.  I found that with my
 > 494, the chip worked in push pull by leaving the controll pin NOT
 > CONNECTED!  for some reason, i could not get it to work with it on the
 > supply +.  Its very simple to leave the pin off to the side, or to cut it
 > off.  But, with a different model of the 494, it may not work like mine
did.
 >
 > and as you already stated, its an easy fix ;)
 >
 > Steve Ward
 >
 >
 > >From: "Tesla list" <tesla-at-pupman-dot-com>
 > >To: tesla-at-pupman-dot-com
 > >Subject: PlasmaSonic SSTC Boards - Mistake Found ! ! !
 > >Date: Sun, 20 Jul 2003 18:00:56 -0600
 > >
 > >Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 > ><dhmccauley-at-spacecatlighting-dot-com>
 > >
 > >I knew my luck would run out someday . . .
 > >
 > >Anyways, an minor error has been identified on the PlasmaSonic SSTC
boards.
 > >The Output Control select pin on the TL494 was incorrectly tied to Vcc
 > >instead of Vref on the board.
 > >
 > >To correct this problem:
 > >
 > >1.  Use an razor blade, knife, or similar to cut the trace going from Vcc
to
 > >Pin 13 of U21 (TL494).
 > >2.  Attach a short jumper wire from the now isolated Pin 13 to Pin 14 of
 > >U21.
 > >
 > >This should correct the problem.
 > >Luckily, this is a very simple fix which can be done underneath the board
 > >and maintain the pleasingly aesthetic looks of the PlasmaSonic SSTC ! !
 > >
 > >The Captain
 >
 >
 >
 >
 >