[ICOM] Schematic and board layout for HM-14 needed

[D C (Mac) Macdonald]

Can anybody steer me to where I might be able
to find a schematic and circuit board layout
for the HM-14 DTMF microphone?  It was an
option for IC-28A/H and perhaps IC-228A/H
radios?

Thanks in advance for any guidance.

73  ---  Mac, K2GKK/5