Re: lisa 2 startup problems

If you are only missing one voltage, repairing the PSU should be a simple task. Likely the filter cap has expired.

Bill.
:-)(((

On Dec 20, 2012, at 6:12 AM, Alex wrote:

Hello Tom,

   You are right, somehow the +12V is missing, I only get +3,4V instead, I only measured +5V and -5V which are ok. I will first try to replace the PSU (a working Lisa should arrive today and I will try swapping the PSU from that one) and than repair it later.     Do you know what the difference might be between a Sun Remarketing 30 MB hard drive and the original LISA hard drive? Can I simply swap them?

    Sometimes, I think we might as well speak German on lisalist :)

Greetings from Kronstadt (Brasov), located in Transilvania, at 15 minutes drive to Draculas castle :)  

Alex

miercuri, 19 decembrie 2012, 08:32:05 UTC+2, tommoni a scris: Hello Alex,

perhaps this could also be a problem with the power supply. If the output voltages are not correct, the psu automatically shuts off. I had the same problem a few years ago, when I received a psu from a collector in England to get it repaired again. So have you ever measured the 5 output voltages: permanent +5V standby, +5V, +12V and -5V, -12V. ? They're (with small tolerances) very important to get a Lisa fired up.

The second error could be a permanet triggered ON/OFF safety interlock. In this case Lisa would not fire up or would only get power for less than a half second and only make a sound like "blip", when you push the power button.

greetings TOM from Bavaria, the center of Europe, with the capital Munich and the origin "Octoberfest"

Am 18.12.2012 um 21:47 schrieb Alex:

> Hi everybody,
>
> long time no post.
> I have done some more tests and come to the conclusion the card edge connector for the IO board has to be changed. I waited 3 weeks for 3 connectors to arrive from Korea and today they finally arrived. I have changed the one from the IO Board and all the sockets and capacitors on the IO board but with little success.
>
> No when I press the power button, LISA turns on but only as long I keep the button pressed, as I release it it will go off again.
>
> Any suggestions?
> Thanks!
>
> joi, 15 noiembrie 2012, 01:17:32 UTC+2, PSchaefer a scris:
> Am Mittwoch, 14. November 2012 20:25:07 UTC+1 schrieb Alex:
>
> On the card edge connector I measure also 0V on the /RESET pin. this means the system is kept in reset state on the motherboard.
>
> There is an electrolytic capacitor (C8) next to the 68000 CPU. Usually it gets leaky, then /Reset is stuck low.
>
> In case you don't have a replacement available, just cut it away. Then you'll have to press the Reset button once to start the CPU (after power-up)
>
>
> Patrick
>
>
>
>
>
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