MegaST 4 will not boot, but looks fine with diagnostics

[exxos]

Have replaced the sockets, now two quality sockets with round contacts are in.
Still with these it doesn't work either.

However it was a very good idea.

Doesn't make much sense.

I would check the CE and OE pins on the ROM and make sure they are switching.. maybe broken trace/bad glue socket, from GLUE to ROM for chip enables, you changed the LS11 already.. but I think you should check the ROM select lines from GLUE to ROM sockets.

If TOS206 worked on another board, then onboard TOS104 isn't working, GLUE does decoding for that...

[guus.assmann]

Finally, I found some courage and inpiration.
And solved the problem.
Jumper W2 had a bad contact.
But it was hidden below the body of the part.
So there was no or a bad connection from the decoding chip to the Eprom.
The board works fine again.

BR/
Guus