Re: Tempest Analog Vector-Generator Question

Ok,

I almost have it fixed. I think what happened is either a bad 15v voltage
regular really wreaked havoc on the AVG and took out a bunch of parts or
someone may have put in a wrong part (maybe a -15v regulator by accident).
That's the only theory I can come up with for so many bad IC's. I didn't
see any physical damage though.

I bridged pins 2 and 3 on both Analog switches (without pulling them out
first). I got the signal all the way to the final amps, and found those to
be bad too. I replaced those and finally got a picture on my scope. So
the two analog switches and the final two amps were all bad. The X and Y
Size pots also broke off so I had to replace those.

So, I guess I just need to wait a few days for the analog switches. Thanks
for the tip!

Matt

On Sun, 2 Dec 2007 21:51:32 -0500 (EST), "Christopher X. Candreva"
<chris@westnet.com> wrote:
> On Sun, 2 Dec 2007, Matt Rossiter wrote:
>
>> I'm trying to figure out a weird issue on a tempest board in the AVG
>> Section. The game is running blind and I traced the fault down to
>> the outputs (pin 2 and 15) of both LF13201 analog switches.
>>
>> I've put the schematic here and dotted where the good/bad signals
>> are. http://games.rossiters.com/images/Tempest.jpg
>
>> Does anyone have any idea why the output on pins 2 and 15 of both
>> analog switches would not work when they are getting proper inputs?
>
> The chip is busted ? :-)
>
> All the analog switch does is determine if the output is inverted or not
> (for cocktail mode). If you are replacing it anyway and don't want to
> wait
> for the new ones to arrive -- pull the chip, put in a socket, jump the
> pins for one of the signals (inverted or not invereted) with a piece of
> wire and see if it works.
>
> If it's not in a cocktail table and you don't plan moving the board to a
> cocktail table you could just leave the correct ouput directly
> connected and not use the switch at all, and have one less thing to
break.
>
>
> ==========================================================
> Chris Candreva -- chris@westnet.com -- (914) 948-3162
> WestNet Internet Services of Westchester
> http://www.westnet.com/
>
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Received on Mon Dec 3 02:35:38 2007