Re: Lisa repair questions

Many thanks to the replies so far!

I could fix problem #2: The #52 error had nothing to do with the COPS 421 chip on the I/O board; I changed the CPU board again and the error has gone. The CPU board works fine in another Lisa, so strange problem with strange solution - but it helped.

The problem with the power supply still exists. I wonder why in the manual there is a temperature sensor mentioned but experts here say there isn't one.. I have now 3 power supplies that suffer from that problem; the capacitors look fine - optically there are no signs that they might be the problem. Should all capacitors be replaced or are there some usual supects?

Another thing: I'm looking for a good working Lisa 1/2 motherboard (that one with the parallel port on the back). Does anyone have a spare board? I'd buy it or trade it against other Lisa stuff (CPU board, I/O board, ... whatever).

Thanks
Rudi

• Original-Nachricht --------
  > Datum: Fri, 12 Aug 2011 09:33:33 +0200
  > Von: tommoni <tommoni_at_email.domain.hidden>
  > An: lisalist_at_email.domain.hidden
  > Betreff: Re: Lisa repair questions
  

> Hi guys!
>
> > the cops chip is in the keyboard.
>
> no, definitively not!
>
> The Lisa keyboard does not have a COPS inside, but perhaps you think
> of something what we call a PRAM chip nowadays. This isn't exactly
> what the engineers built in to store the data inside, telling the
> system software what kind of keyboard is plugged in, when you fire up
> your Lisa and the selftest was done.
> It's a kind of... let's say: E-Prom containing data about the
> "nationality" of the keyboard e.g. whether you have a standard
> "qwerty" also known as u.s. layout or e.g. a german "qwertz" keyboard.
>
> Some of you guys here in the LisaList know that I'm resident in
> germany/europe. That's why I own several different types of keyboards
> for the Lisa and know the differences.
>
> But, if you think that the whole keyboard-layout is stored in that
> device inside the keyboard, you're wrong. As far as I know it's only
> a 4 bit code, which is transfered to the Lisa short after booting.
> After that, the Lisa even changes the language in the menue-bar due
> to that keyboard-code.
>
> So Rudi, use a "german keyboard" and after that boot with an "english
> keyboard" and you will see some different system menues, although
> using the same Lisa OS
> I think you asked me that some years ago, when you picked up the Lisa
> spareparts and the power supplies here in southern Bavaria.
>
> The second problem (in fact it's your problem #1) with the automatic
> shut-down is caused by the little board inside the psu, which watches
> the correct voltage. It's a safety unit to prevent damage due to
> overvolt or overcurrent, but also to inhibit start, if there's an
> undervolt situation. These parameters are all monitored analogue in
> the secondary part. As far as you know, there's not monitoring in the
> primary voltage section... do you remember ;-)
> But what causes such an overvolt or undervolt situation after a few
> minutes?
> Replace the electrlyt-caps in secondary voltage unit, located near
> the output pins of the psu-board; they must be bad due to their
> age... they're dry for shure.
>
> All this has been reported several times in the LisaList a few years
> ago, but I think it's hard to find if you don't search for several
> keywords or for a longer time than 5 minutes :-)
>
> ...and the psu doesn't have a specific temperature sensor.
>
> greetings: TOM from Bavaria, the center of europe, the country with
> the marvellous castles of Koenig Ludwig, the alps and the original
> Octoberfest in Munich
>
>
> Am 11.08.2011 um 04:16 schrieb barana:
>
> > the cops chip is in the keyboard.
> >
> > Rudolf Brandstötter wrote:
> >> Hello Lisa fellowers,
> >>
> >> I have some repair questions I nowhere found in the well known
> >> Lisa documentation... it may be also helpful for others.
> >>
> >> 1.) I have 2 1.8AMP power supplies that shut down after 5-10
> >> minutes when they are warmed up. When they are warm the Lisa shuts
> >> down immediately; if you wait 1h or so it runs again for some
> >> minutes.
> >> I read in the owners guide that the PS has a temperature sensor
> >> that shuts down the PS if the temperature is over 90°centigrade.
> >> My question: where the hell can I find that sensor on the PS? Can
> >> you tell me the location? Any experiences with that part?
> >>
> >> 2.) One Lisa always shows error #52 when starting. The problem is
> >> that the COPS chip is not the problem (changed i/o, MB, CPU
> >> boards.. and everything with another working Lisa where this
> >> problem does not exist). I can only imagine that the cabels inside
> >> or the power on/off switch causes this problem. Any experiences
> >> with that sympthom?
> >>
> >> many thanks for any answers
> >>
> >> Rudi
> >
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