Re: PlasmaSonic SSTC Boards - Mistake Found ! ! !

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

Original poster: "Steven Ward by way of Terry Fritz <teslalist-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>

Hi Dan,

i suspected that the control pin does indeed need to be tied to the 5v ref.
Actually, when i probed the control pin, there was 5v on it, though it was 
left unconnected.  Eventually though, the chip seemed to stop working quite 
right, so i had to ditch it.  Im not totally sure what exactly happened.
Next time i will be sure to tie it to the internal 5v supply on the chip.

Steve Ward


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: PlasmaSonic SSTC Boards - Mistake Found ! ! !
>Date: Mon, 21 Jul 2003 07:54:10 -0600
>
>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
> >
> >
> >
> >
> >