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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