Amiga 500 multiplexer doesn't multiplex!

[mongo]

Check that R404 is 120 Ohms and if that is fine, replace U33 (74F04).

[mongo]

The signal involved is named _CCK and comes from Agnus. So you could try swapping that out also.. In case another chip is shorting it out, it also goes to Paula and the external expansion slot.

CCK comes from Agnus. _CCK comes from the 74F04 inverter at U33.

If the problem was the CCK clock from Agnus, it's likely there would be other problems besides the mouse/joystick as CCK is used by Paula, Denise, and Gary.

[mongo]

I cannot find the R404. Do you know where it's located?

I can find all others in the range R402-R406 however.

What revision is your motherboard?

[mongo]

Still can't find the thing :/
I might be blind, however... :confused:

Not blind. Revision 6A boards don't seem to have R404. That might have something to do with it.

Check if the connection between pin 4 on U33 and pin 1 on the 74HC157 is Ok and make sure that pin 3 on U33 isn't shorted to ground.