A500 Won't Recognize 3.1 ROM

[mechy]

Howdy!

I'm running into a strange issue with my Rev 5 Amiga 500. I can't seem to get it to boot from a 3.1 ROM (black screen). The EPROM has been modified as required to work in a rev 5 motherboard.

The system will boot to it's stock 1.3 kickstart with no issues. Here is what I have tried:

*EPROM tested in another Amiga 500 and works.
*Reseated all socketed ICs.
*Replaced CPU with known good CPU.
*Tried a different 3.1 ROM that is also tested as good.

Here is the keyboard LED error code I see:
https://www.youtube.com/watch?v=gBcCypJiNSc

If both mouse buttons are clicked to enter the menu, it loads part of the menu and then freezes:



I am at a loss. Any ideas? I don't recognize the keyboard error either

If the continuity checks out you may check the eprom speed, i wouldn't think it would be the problem but if they are using slow eproms timing might be right on the edge.

[mechy]

I'm impressed that they have "local electronics junk stores" in Texas that have Amiga parts!!!

I've got tickets to a tech event down there in Austin in September, anyplace you can recommend?

...btw, ripping my A500 apart in a few weeks for some upgrades.  It's a 6A, if you can't find those values before then I might be able to get them for you.  Not anxious about removing my VXL*30 though, haha.  

Lol, i am jealous, i am in texas and our junk stores have nothing amiga ever ;/
 I am in a small town though

[mechy]

That is very helpful, thanks for that!

I'll get a hold of a logic probe and oscillator this weekend and start poking around the CPU.

It's certainly possible that one of these resistor packs could be faulty.

when you burned the eprom,did you fill it completely, i.e. concatenate it to double it them burn it to the full 4mbit eprom... hope that makes sense?

if not,then iirc it may address the empty half or some such and not work.