Question: AES revision 1 bootloop?

Hi,

I need some advice about an AES revision 1 w/o daughterboard which I grabbed locally.
I installed a unibios and right after that it booted on a plain white screen. Well it didn't last as there is now another screen going on and off. Looks like a boot loop.
I could check the traces between bios and 68k based on the pinout from JNX. Only pin 20 (OE) differs by connecting to a 74LS08 and itself coming from PRO-CO
Also tried tried booting with the diagnostic bios but same results.

As anyone here seen this kind of screen before?

I've not seen that one before but the bootloop is the watchdog circuit restarting the system over and over again because it doesn't work as it should. It probably is a bad trace so get your multimeter and datasheets out and measure continuity between the bios chip and the 68000.

You probably botched the UniBIOS install. Did you at least put in a socket? You'd have to remove the socket or the soldered UniBIOS chip and go over the through-holes with a careful eye and a multimeter, check for any broken traces or solder rings.

It's also possible the UniBIOS EPROM isn't burned correctly.

Pingu said:

I've not seen that one before but the bootloop is the watchdog circuit restarting the system over and over again because it doesn't work as it should. It probably is a bad trace so get your multimeter and datasheets out and measure continuity between the bios chip and the 68000.

Click to expand...

HeavyMachineGun said:

You probably botched the UniBIOS install. Did you at least put in a socket? You'd have to remove the socket or the soldered UniBIOS chip and go over the through-holes with a careful eye and a multimeter, check for any broken traces or solder rings.

It's also possible the UniBIOS EPROM isn't burned correctly.

Click to expand...

Thanks for the replies, I did put in a socket although I must admit there were couples of bad through-holes. It's all patched up now.
Bad links between bios to 68000, LSPC-A0 and work ram were fixed up. This old revision board does not have NEO E0, G0 but PRO C0, B0.
It still shows the same image with or without any bios. Screen color is different when booting with a cart inserted and got the clicking sound.
Yes I am stuck here...

Display w/o cart and w/ or w/o bios - No clicking sound


Display w/ cart inserted and w/ bios - W/ loop clicking sound

If you didn't destroy the old bios while removing it put that in (since you know it is good) put that in again and search for broken traces to patch. Also if you did burn the unibios yourself check that you got the endian correct.