On Wed, Aug 16, 2017 at 6:28 PM, Al Kossow via cctalk <cctalk@classiccmp.org> wrote: > I was looking at this thread > https://forum.kryoflux.com/viewtopic.php?f=3&t=749 > > And they mention the data they were looking at has AGC applied. > > I didn't know any floppies used AGC in their read channel and in particular > I'm trying to find a block diagram or schematic of the logic in the Teac > FD-235 > > I can't find a detailed description of this drive anywhere (I'd be surprised > if > there was ever a maint manual for it). There are some nice pictures of the > guts > of the drive at > https://commons.wikimedia.org/wiki/File:TEAC_FD-235HF_-_controller-8879.jpg
There most certainly was/is a service manual for at least one version of the Teac FD235. I bought it new when the drives were current (as I added such a drive to my IBM5170) -- for serveral times the cost of the drive... But you know me and service manuals. I have just looked at it, and unfortunately it is of no help with this question (I assume that if manuals for other versions of the FD235 exist, they will be similar). Most of the manual is replacing mechanical parts, doing the head alignment, etc. There are schematics of the spindle motor and the logic PCB in the manual, but the latter is one big ASIC (containing all the digital circuitry, the read channel, etc) with a few passives hung off it. There is no theory-of-operation of that IC, or block diagrams in the manual, alas. -tony
