exxos's Atari, Amiga & retro forum

It looks like VIAs do not get CLK signal at all. So it looks like 7404 are faulty, or there is issue with traces.
I need to dig out schematics to exactly board which I have and check where clock disappears.

EDIT!!
It was ROM and JP5 was not soldered correctly!

Now it passes initial booting, next step test rest of the drive.

Excellent news! Which board is it BTW? I guess shortboard 250442 due to J5?

Yes it is.

But drive is still not working correctly.
Can't format floppies, or read anything (this is not a surprise as I don't have any known working floppies)

At this point it looks like faulty drive head, which woukd be game over...

Still it may be write protect or drive closed sensors or something like this

See page 18 of this PDF for how to check the read/write head resistances -> https://www.classic-computing.org/wp-co ... MANUAL.pdf

Also may be worth swapping the VIA's again, failed IC2 can cause this, as can failed UC1 (gate array), failed UE3 (LM311), UF3 (LM592), UF4 (LM592).

I have red to blue R/W coil end to end 15k ohms, should be 30ohms :|

Yeah that's not good, is it a newtronics mechanism?

Yes it is. Apparently very common fault.