Pinout for SED9421

Tony Duell ard at
Thu Nov 24 14:45:22 CST 2005

> On 11/23/2005 at 8:01 PM ard at wrote:
> >Does anyone have the pinout (or a datasheet) for the SED9421 chip (18 pin 
> >DIL package). 
> I found this on a Japanese site:
> 1.XG
> 2.XD
> 3. ph1
> 4.NC
> 7.DATA
> 8.MFM/FM
> 10.VSS
> 13.LPF
> 14.WCLK
> 15.ph2
> 16.NC
> 17.NC
> 18.VDD

Thanks for that. It seems to make sense against the PCB I'm investigating...

> It appears to be a VFO for use with the SED9420C data separator (like you'd
> find in an Amstrad CPC).

I never thought to look in Amstrad service manuals (and I have quite a 
number of them). They sed the SED9420 quite a lot (in the CPC, PCW, etc), 
but never with an external VCO.

Are you sure the SED9421 is not a complete data seperator? The PCB I am 
looking at (from an Epson PF10 drive unit) doesn't seem to have much else 
around the 765 disk controller chip.


More information about the cctech mailing list