Re: Lisa not powering up

Hi Tom,

thanks for your feedback. I'm 100% shure: the error has to be located in the motherboard.

Have you ever switched the motherboard for testing? Not the whole rack with all boards, only the motherboard itself? If everything would work, then you could be 100% shure, that the motherboard will be the cause of the problem.

The most likely and the most common error is a bended (or corroded) pin of the connector array, in which the boards are plugged in. I would recommend to check all of them with a low-ohm-multimeter. It's plenty of work, because you have to measure every pin, when the board is plugged in. There's not much space for measuring, so you have to remove all boards and test the connections one after another. But you wrote: "The connection seems to be fine". Well, "seems" is perhaps not shure enough :-)

As there are no active parts on the motherboard, so it must be an error in the connections of this board or corroded tracks themselves. The two parts near the ports which might look like an integrated circuit are resistor-arrays. I had repaired a Lisa 2 where these arrays were heavy corroded, but the Lisa started. I'm not shure what will happen if these arrays are shortcut, but the Lisa should start anyway.

As you wrote "badly corroded motherboard", you will have to do some measurement-work. First the connections, then the tracks on the board itself.

keep me informed and have a nice weekend

greetings TOM from Bavaria, the center of Europe, the country of the Alps, the marvellous castles of Koenig Ludwig and last but not least: The original Octoberfest

Am 10.01.2014 um 04:32 schrieb Tom Frikker:

> 4. The connection seems to be fine between the boards (and yes, I
> am talking about the horizontal board with the plugs)
> 5. These connections are also fine.
> 6. Also fine.
> 7. The shutdown switches are functioning normally with another card
> rack.

-- 
-- 
-----
You received this message because you are a member of the LisaList group.
The group FAQ is at http://lowendmac.com/lists/lisa.html
To post to this group, send email to lisalist_at_email.domain.hidden
To leave this group, send email to lisalist+unsubscribe_at_email.domain.hidden
For more options, visit this group at http://groups.google.com/group/lisalist
--- 
You received this message because you are subscribed to the Google Groups "LisaList" group.
To unsubscribe from this group and stop receiving emails from it, send an email to lisalist+unsubscribe_at_googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.