BFG9060 black screen on my Amiga 4000D motherboards, how to fix?

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Here is my test setup: Acill A4000D motherboard with ReA3630 and two BFG9060 cards including Firestorm PCI daughterboard, Multifix-AGA and a replica A4000D case

I had two summer projects this year that I recently finished. One was an Acill A4000D replica motherboard and the other was a Hese made A4000+ Alice A4000D CR motherboard replica. You could say two brothas from different mothas or something…

Both motherboards worked fine when doing basic test runs, however they both failed to run with a BFG9060. All I got when running them with a BFG9060 060 CPU card was a black screen.

amiga-4000d-motherboard
Amiga 4000D motherboard in shiny red

Anyway, as usual building them up was pure pleasure from start to finish. I even enjoyed desoldering the Acill A4000D motherboard from a few passives and pin headers someone else had a false start with. I mean, off course you want a full set of pin headers soldered to your 400+ small parts PCB (not really).

The A4000D motherboard fully built with a BFG9060

The motherboard was all built up and looking good in shiny red matching a BFG9060 with a mystery (rev. 1) 060 I built last year.

As good as it was looking it failed to run with the BFG9060. It was working fine with the A3630 CPU board I built earlier this year, but not with the 060 card. That reminded me that I had the same problem with my Alice A4000D motherboard a couple of weeks ago.

A4000+ Alice motherboard during assembly phase

The Alice A4000D has an 030 CPU on the motherboard so it does not need a CPU card. It was working fine with the on board 030.

Here is the A4000+ Alice motherboard during the testing phase inside the A4000D case

I got the suggestion to try a new delay line as that could be the problem the CPU card failed to run. As the A3630 has exactly the same CPU as the one mounted on the motherboard, it is difficult to say if the A3630 was running or not.

Testing the A4000D motherboard + BFG9060 with a PicoPSU

If you are in this hobby you have to grow a passion for trying all hardware combinations to find the solution. In this case, the reason for the Amiga 4000 getting a black screen when running a BFG9060 was the PSU as everything seemed to run fine with another PSU than the SFX one I had in the A4000D case.

I changed the SFX PSU that previously was working fine with the EXACT hardware setup I am running here (but different Amiga 4000 motherboard) with a small ITX PSU and suddenly DiagROM worked fine and detected the 060 CPU.

This lead me to believe that maybe the PSU was not pushed too hard as some ATX PSUs fail to run if there is a tiny load on them (or something like that). So I decided to do a final test by adding some cards to my A4000D and try the SFX PSU again.

Unfortunately it did not start with the SFX PSU and 060 card even if I loaded the machine with all Zorro slots filled, including adding an old 3.5″ harddrive.

So next step is to get a new SFX PSU. But at least I know I have to working motherboards!