Help on HP 82901 drive

I have now found my HP dual 5.25" drive, and it's a 82901. I have, of course removed the cover and extracted the controller board. I;ve not looked at it properly yet, but the pinout of that chip appears at a glance to be _very_ close to that of the WD1793 (closer to that than the WD1771, for example). More data when I've done a little tracing. [...] That one suprised me last night, becuase I couldn't understand why there'd be a DTL chip on this board. Am I correct it's a type for 1810-0325? That appears on my board _and on the board of one of the disk drives _ and is a 150 Ohm resistor array (terminator for the floppy drive cable). I am pretty sure the read clock VSO (and part of the PLL circuit?) is the sea of discrete transsitors at the front edge of the board. There's a twiddlepot which presumably sets the read clock frequency, but I'd not turn it yet. HP used a lot of strange circuitry in this sort of thing. Current mirrors and the like. But let's at least prove your drive has problems in that area befroe worrying. -tony