PAK issues

pakman · Post by **pakman** » 08 Feb 2019 21:36

Next: Remove the U5 jumper wire, and assemble U5 instead. Try to boot.

Post by **PhilC** » 08 Feb 2019 21:43

with U5 inserted and the wire removed from U1 also it does boot to desktop

pakman · Post by **pakman** » 08 Feb 2019 21:47

Ok, add GAL U4 and try to boot

Post by **PhilC** » 08 Feb 2019 21:51

It gets to desktop with U4 inserted as well but wont boot the floppy image I had on Gotek but one step at a time :)

pakman · Post by **pakman** » 08 Feb 2019 22:02

That's weird. Check the voltage at U4 pin13, should be high. Then all outputs of U4 should be tri-stated, essentially the same as if there were no U4 at all.

Post by **PhilC** » 08 Feb 2019 22:05

I have 4.48v on U4 pin 13

Post by **PhilC** » 08 Feb 2019 22:06

I've also put u2 back in and it boots if that helps

Edit:

In fact it ill boot with all 5 Gals inserted

pakman · Post by **pakman** » 08 Feb 2019 22:10

Let's fix U4 first. Get another GAL (not the U4 you are using right now), program the P4 JEDEC, and try again to boot.

Post by **PhilC** » 08 Feb 2019 22:16

Ok, just U3, U$ and U5 inserted and it now doesn't boot

pakman · Post by **pakman** » 08 Feb 2019 22:19

The very same U4 as before? Or a new U4?

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