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Path: utzoo!utgpu!lharris
From: lharris@utgpu.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Help needed with Tallgrass hard disk
Message-ID: <1987Apr17.183535.21308@gpu.utcs.toronto.edu>
Date: Fri, 17-Apr-87 17:35:35 EST
Article-I.D.: gpu.1987Apr17.183535.21308
Posted: Fri Apr 17 17:35:35 1987
Date-Received: Sat, 18-Apr-87 04:39:14 EST
Organization: University of Toronto Computing Services
Lines: 23
Checksum: 06337

Hi.  I recently thought I got a good deal on a Tallgrass 3135 hard disk
system.  It has a 35 meg drive with 40 meg tape backup.  The problem:
It appears to function properly at first.  Directories get written, files
transfer but they get garbled .  Files under about 12K transfer fine.
Garbled files actually only have 1 byte missing from them.  On a file compare
one finds the data offset by one byte (like one just vanished). 
Tallgrass has no explanation for this - they want to sell a $100 service manual
that doesn't even contain schematics - just flowcharts for which board to replace.

The interface consists of 3 boards - a small data buffer board in the PC
- an analog board with the phase-locked-loops for disk and tape writing
- and a digital board with ram and lots of LS244's (it also calculates a CRC
for all data transfered).
I have replaced the memory with no luck, reset the PLL - no luck, and I am
considering replacing the IC's that make up the CRC generator.

Any ideas on what could cause 1 piece of data in a stream to get lost?
Any help or ideas would be very much welcomed.  Tallgrass's only solution
is to swap boards for over $300 - there isn't even $300 worth of components
on the thing.

Thanks in advance..
/leonard