Lisa jittery screens

From: Jeffrey H. Ingber <jingber_at_ix.netcom.com>
Date: Mon Dec 30 20:14:01 2002

On Mon, 2002-12-30 at 21:04, John Lawson wrote:
> You have not siad what you mean by 'jitter', and I am not a Lisa owner..
> perhaps this is a symptom common to the breed. But I would ask: is it
> horizontal, vertical, is the raster fragmenting, is the brightness
> varying?

The "jitter" manifests itself as a very slight (distance-wise) and rapid
vertical bouncing. The brightness is very consistent.
 
> Is it a power supply problem that you are adjusting? If so, when it
> returns, is it time related? Temperature related? I see you have made the

I'm pretty sure it's a power-releated problem as adjusting the supply
temporarily fixes the problem. Heat may play a role in this, as the
jitter subsides to some degree when the system heats up. The
adjustments were made to a "warm" system.

> adjustment in Sept., but nothing since then? If it takes three months for
> the problem to return, I'd be tempted to adjust for the party, then fix it
> afterward....

I'll do this for now, but it shouldn't need to be adjusted so often.
It's a rather arduous process.

>
> Just my two cents, and worth every penny of it.
>
>
> Cheers and Happy New Year!
>
> John
>
Received on Mon Dec 30 2002 - 20:14:01 GMT