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Re: I could use a hand locating hardware bits and pieces and/or technical documentation for repair.

Newsgroups	comp.sys.3b1
Date	2015-12-22 21:18 -0800
References	(1 earlier) <54468d59-7b83-4211-8f4c-5d8dd4be215b@googlegroups.com> <f6403a08-7703-4361-be99-91ffe9aa5de0@googlegroups.com> <slrnn7hgfe.lon.BPdnicholsBP@Katana.d-and-d.com> <aaa27f8d-040f-457e-8110-820a7668ff44@googlegroups.com> <slrnn7k4au.4ih.BPdnicholsBP@Katana.d-and-d.com>
Message-ID	<4311a190-425f-4b34-aadd-caa11257d7a4@googlegroups.com> (permalink)
Subject	Re: I could use a hand locating hardware bits and pieces and/or technical documentation for repair.
From	Chris Smith <protheus@byteorder.net>

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On Tuesday, December 22, 2015 at 9:13:53 PM UTC-6, DoN. Nichols wrote:
> On 2015-12-22, Chris Smith <protheus@byteorder.net> wrote:
> > I'd be tempted to try it myself, depending on the surface mount parts.
> > I'm not terrible at hand-soldering surface mount parts.  Best I've done
> > so far is 28 pins at .65mm pitch... on the soldering station at home,
> > which has a not-too-small wedge tip.  I'll probably buy something a bit
> > higher precision for it at some point.
> 
> 	O.K.  One benefit of the stereo zoom microscope would be the
> ability to examine for solder bridges between adjacent pins.

Yeah, it sounds like something I may want to put on the list of things to get eventually, now that you mention it.  

> 	The first thing to check would be the chip in the socket for the
> WD-1010.  If it is a WD-2010, then the board has at least been modified
> to allow more than 1024 cylinders (a limitation on the WD-1010 chip).
> If there are also extra wires in the area near where the data and
> control cables plug in from the hard drive, then it is likely that it
> was also modified to allow more than 8 heads, and a second drive.  (Look
> for the ICUS modification data in the download sources to find out how,
> but details can vary from system to system.  I avoided using a board
> with extra parts, and instead located a spare 20-pin socket layout on
> the board (different locations with different versions of the board),
> and with a bit of trace surgery was able to use the existing
> differential driver and receiver chips for data to/from the second
> drive.  (I also did a bit of other tricky work to get both data paths
> through a single ribbon cable, and put both drives in an external
> housing (originally for a 3B2 computer, so the color scheme matched).
> Also a little tricky bit to use the 5V for the internal drive to turn on
> the power supply in the external housing, so I did not have to switch it
> separately.  Obviously, for systems modified the way I did it, the
> location of the spare 20-pin socket lead layout would be somewhat
> different for different versions of the motherboard.

I don't believe there's any extra cabling around the drive, but I'll need to check on the controller chip next time I have it open.

> 	Different versions of the machine (at least different between
> the 7300 and the 3B1 (half-height vs full-height hard drive) have
> different fan setups.  IIRC, the 7300 came with two fans, and the 3B1
> had one fan replaced with a block of foam rubber.

Ours are both 7300s technically.  Two fans, but I remember the fans in mine being significantly different-looking than the ones in hers, and they've got some connector splices that look aftermarket.

> 	That makes life easier.  Of course, the existing date(1)
> program would not allow setting the date to beyond the last day of 1999.
> My work-around when I had to deal with it for a while after that period
> (helping recover data from someone else's failing disk drives) was to
> write two simple programs -- one on a Sun workstation which printed the
> date in the numeric format (the 32-bit number which keeps the number of
> seconds since the first moment of 1970 GMT), and the other on the 3B1
> which sets the time by force-feeding it that same number.

That's not a bad idea.  Simple enough and it does get the clock up to the right time.  I'm not absolutely sure my battery is dead yet, on the other hand.  Guess we'll find out when I get the drive replaced. :)  Keyboard is basically dry, so I may leave it on the heater register again overnight and throw it back on tomorrow.  We'll see if that helps.

Chris

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