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>

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