From: sometomtom@tomtom.com
Hey Jim,
Do you have a website with photos to help show what you did? Maybe some
component references. Trying to follow your instructions is a little
difficult without some additional clues to the specific locations you're
referring to.
Thanks,
Glenn
"Jim DeClercq" wrote in message
news:gelg6o$i7t$1@reader1.panix.com...
> Having had a lot of trouble getting hard drives bigger than 4 gig
> to work on a TT030, I thought I would try a Compact Flash card,
> which does not draw much current, and to my surprise, I still had
> bus problems.
>
> This problem has been getting worse, and having worked as a
> failure analysis engineer, I thought I knew what the problem was,
> and I was right, one more time. I went into great detail the
> first time through, but the process is easy and quick.
>
> Five lengths of number 26 stranded wire, or metric equivalent, in
> two colors, about 18 inches, or metric equivalent. Strip one end
> of each, for a half inch (12 mm) twist together, and tin. One
> color gets laid across the bottom end of pins 1 to 3 of the bottom
> of the power connector, and soldered to them. The other color
> gets laid across the bottom ends of pins 5 to 8. Avoid pin 4,
> which is -5 v.
>
> Pins 1-3 are +5, pins 5-8 are ground. The empty pin is at the
> other end.
>
> The free ends of one color, mine was green, and leaving one
> spare, were connected to the plus ends of bypass caps
> geographically closest to the SCSI chip, the TT memory socket,
> the back ST memory socket, and the front ST memory socket.
>
> The free ends of the other color, mine was black, were connected
> to the ground ends of those bypass caps.
>
> When I did this, for the first time, I measured resistance
> between caps and socket pins, and found that the closest had the
> least resistance.
>
> The cap ends, after measuring, using a DVM with a semiconductor
> setting, to see which end was closer to power or ground, were
> marked with two different colors of paint pen, although anything
> that does not interfere with soldering can be used. After that,
> the solution went fast.
>
> This is all done on the bottom side of the board. Having done
> this, everything seems to work fine, and I have a DVD writer and
> one ZIP drive on the external bus, and they both work. There is
> no sign of anything wrong now, and if the printer port fouls up,
> I have a set of spare wires for connecting to a bypass cap in
> that area.
>
> If you look at a TT030 motherboard, you will see wide power
> traces disappearing down very small plated through holes. If they
> were not heavily plated, a little bit of corrosion, and a lot of
> power is lost, and things that drive the bus do not get enough to
> drive it to full voltage. If I had designed that board, the holes
> would have been much bigger, and the plating thicker.
>
> I have not loaded this machine to its historical full, which was
> a DVD writer, two ZIP drives, one tape backup, and a scanner, but
> will get to that, and if on the slight chance that does not work,
> I will find how to fix that. And I will report on how to do that.
>
> I use a windoze machine at work, and do get work done, but for
> personal purposes, a TTM 195 monitor on a TT030 is the perfect
> tool.
>
> This done in pico from MiNT 1.15.12.
>
> Jim DeClercq
>
>
> --
> --
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