EII Diagnostics

[midipuppies]

In the diagnostics adendum, it refers to the 'SIO'.
(http://www.emulatorarchive.com/assets/PDF/EII%20Diagnostics%20Manual.pdf)
Anyone know where/what this is?

Can't seem to boot up from either drive. Got new scanner and main EPROMS in. Drive voltages check out, but the 12V reads about 15V.
Drive tries to spin up (sometimes) and the dispaly either shows boot in progress and then the software rev, or garbage characters. Drive sometimes clicks as if trying to load. Tried changing out drives with three others- same result.
Tried cleaning power terminals at the solder points (mine has no connector, just silicone on top).
Tried removing and cleaning IC's 1&2 and the entire memory expansion board.
Tried disconnecting lower drive and this results in the display saying insert diskette.

Anyone?

[Escobar]

The Emulator II 'architecture' is built around the Zilog processor Z80A. Zilog also made several peripheral circuits to handle In and Out communication to release the main Z80A processor from those time consuming tasks. SIO stands for Serial Input Output -circuit that takes care of the serial communication with diskdrive, harddrive etc. Another circuit is PIO which stands for Parallel Input Output. It might be problem with that circuit (SIO) though very rarely. If so lucky for you, the processor is commonly availible and still in production!

[midipuppies]

Any idea what I can check next Esco?

[dr.c]

Its written : Z80 A SIO/2

Follow the calbe from the floppy till the connector on the PCB, then you will find it.