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Old 02 May 2018, 19:44   #35

glenn's Avatar
Join Date: Nov 2015
Location: stockholm Sweden
Posts: 89
Originally Posted by Daedalus View Post
Yep, it's a very strange one alright. The A20 line will be driven by the CPU for RAM access, though it doesn't drive the RAM directly. I don't know the A4000 all that well, so maybe someone with more experience like Chucky would be better placed to go into the finer details. To me though it looks like Alice and Gary are both involved, working together via U212 to generate the RAS and CAS signals from the address bus. If neither Alice nor Gary are getting an A20 signal, there has to be something more fundamental wrong.
Yes, it is strange, it is like it never even try to set it high. ..Hmm, maybe if something is holding the A20 down, shorting it to ground or something.. IƤll take a look and see if I can find anything. ..On the other hand, then the fastmem shouldnt work either ?

Originally Posted by Kin Hell View Post
The underlying problem will probably be poor tacks/damaged components in/on the mobo, as a result of prior battery leakage.
Yes, thats the most common fault, that and damages from leaking capacitors.. however, nothing near the chipram seem to be damaged here, and I measured everything.

Depending on the extent of the original leakage & how severe it was, it's normal for Amiga 4000's to suffer Clock, memory & sound issues at some point of their life-span. Pretty much every component on the Battery side of the Mobo is at risk from acid leakage,
Ys, RTC and sound is very common, even fastram, but not chipmem usally.

You'll probably need to send the board away for a competent repair guy to fix.
Will not happen, especially not after a friend sent a board to a well known amigacompany and got it back a year later in worse condition, more broken and they wanted money for it too..

I'm fully capable of doing this kind of repairs myself, I just never had any problem exactly like this before, but i learned a lot about both DRAM and how chipmem is detected now

Originally Posted by cpiac64 View Post
use diagnostic from "Logica", you can find in "Amiga forever"
I dont think the logica ROM is better than Chuckys DiagROM at any point nowadays ?
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