26 Jul
2004
26 Jul
'04
9:33 a.m.
Subject: Re: Anyone have/know of Persci drives, parts
1. There are no microcontrollers on the 270/277 series drives (I believe
that there were on the later 299 drive)
OK< I've only seen on Persci drive, that on my CASU Super C S100 system,
and I can't remember what model it is. I do remember a 40 pin EPROM
microcontorller (with a quartz window), which iIRC was an 8748.
2. The board has a huge amount of analog circuitry on it, both for the r/w
head and the very complex servo system, and is not easy to troubleshoot.
I really can't believe it's impossible, or indeed any worse than many of
the things I've worked on. From waht I remmeber, the servo circuitry is
similar in concept to that in, say, an RK05 drive, and I've worked on
those.
3. None of the components on the board, including the 50 or so ICs, are
socketed.
None of the 1000+ ICs in my PDP 11/45 CPU (including the MMU and FPU) are
socketed. This has not stopped me repairing it. Actually, I am not sure
what benefits socketed ICs provide for troubleshooting/repair --
desoldering and replacing the faulty IC is not a major job, and you
shouldn't need to remvoe ICs other than the faulty one (in other words
troubleshooting should not consist of replacing ICs until the thing
starts working).
No argument that the boards ultimately could be repaired, but it's not
nearly as easy as your post suggests. Plus there are 4 other major but
I will admit I've not worked on this model of drive. But I have worked on
things of greater complexity -- without service information -- and got
them going. I am darn sure this board can be repaired.
smaller boards on the drive in addition to the large
main board.
-tony