Re: Lisa I/O board troubleshooting, and schematic weirdness

• On Mon, 3/26/12, James MacPhail <gg__at_email.domain.hidden> wrote:

> The 2/5 and 2/10 use the same CPU board and ROMs. Although
> there are a couple of revisions, they are essentially
> interchangeable (with the exception of the 3A screen
> modification kit ROMs which need a different CPU board video
> PROM).
Ah. I was under the impression that the CPU's ROM had to be the same rev as the one on the I/O board. But.. now that I think about it, those are two separate ROMs - hence the "H/88" revision on the screen - the first is the CPU, then the I/O. This CPU is rev F, and I was thinking that it had to be compatible with the I/O board ROM.  

> The I/O board for the 2/10 is different from the 2/5, so
> their schematics differ...

That's just it... they don't. I have both in front of me. *Both* schematics show that chip. And looking more closely at them this morning, I think they're both exactly the same - at least this page is. They're marked appropriately (Lisa 1 and Lisa 2/10), but I think this page is the same. Now, there are differences elsewhere in other pages of these schematics, but I'm wondering if this one page is incorrectly marked as being for the Lisa 1.  

Lisa 1 - http://lisaem.sunder.net/LisaSchem/Lisa1SysIO3.gif Lisa 2/10 - http://lisaem.sunder.net/LisaSchem/Lisa210SysIO3.gif

> Once you've dealt with the battery corrosion issue, a
> bad/dirty backplane/motherboard connection is often the
> cause of an I/O board self-test error, but I'd suspect the
> corrosion issue first.

Yeah, I do need to further investigate this - I cleaned up the corrosion in that corner, and cleaned up the edge connector, but I haven't actually sat down and checked all the vias at the bottom of the board - I would not be surprised if one of those is making poor contact due to the corrosion. I'll work on it some more tonight and see what I can find. I'm testing in a known good/clean Lisa 2/10 backplane, as I haven't finished getting this 2/5 one fixed. I really wish I had a schematic of the backplane - has anyone ever seen one?

-Ian

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