I know that the TRS-80 Model 4P uses a PLL to do the high res video mode,
and that a common cause of crappy quality display is the setting of the VCO
cap.
My 4P was unsable until I adjusted the cap, not it is beautiful.
regards
Doug Jackson
MSS Operations Manager
Citadel Securix
(02) 6290 9011 (Ph)
(02) 6262 6215 (Fax)
(0414) 986 878 (mobile)
> -----Original Message-----
> From: Curt Vendel [mailto:curt_at_atarimuseum.com]
> Sent: Wednesday, August 07, 2002 1:43 PM
> To: cctalk_at_classiccmp.org
> Subject: Re: TRS-80 Model III
>
>
> Sellam,
>
> Are the boot straps on eproms on the motherboards??? You
> may be facing
> possible bitrot, that's one possibility.
>
>
> Curt
>
> ----- Original Message -----
> From: "Sellam Ismail" <foo_at_siconic.com>
> To: "Classic Computers Mailing List" <cctalk_at_classiccmp.org>
> Sent: Tuesday, August 06, 2002 3:31 PM
> Subject: TRS-80 Model III
>
>
> >
> > I am trying to get a TRS-80 Model III working. When I turn
> it on the disk
> > drive spins for a while looking for a disk I presume. All
> I get on the
> > screen are wispish diagonal lines as if the horizontal hold is all
> > whacked.
> >
> > I managed to unstick one of the video adjustment knobs on the left
> > underside but all it does is affect the brightness level.
> The other one
> > requires a screwdriver to move at all (shimmying it up and
> down) and does
> > not seem to affect the display. I haven't opened it yet to see what
> > adjustments are inside. I'd rather not, but there don't
> seem to be any
> > adjustment pots accessible from outside the case.
> >
> > What's weird is that I have access to a bunch of TRS-80
> Model 3's here at
> > the ACCRC and pretty much all of the ones I have played
> with so far are
> > basically "dead" in this manner. The one I'm working on
> just came in
> > today and is in the same state. Also, the video knobs on the left
> > underside are all stuck on everyone I've tried to get
> working. What is
> > the deal with that? Do they get rusted over time or
> something? Very
> > annoying.
> >
> > The fact that the disk drive spins up when I turn it on is
> a good sign I
> > hope.
> >
> > Any help on this would be appreciated. I know next to zero
> about the
> > TRS-80 series.
> >
> > Sellam Ismail
> Vintage Computer
> Festival
> >
> --------------------------------------------------------------
> ------------
> ----
> > International Man of Intrigue and Danger
> http://www.vintage.org
> >
> > * Old computing resources for business and academia at
> www.VintageTech.com *
> >
>
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