[sdiy] New sounds for TR-707, readable schematics?

[Metrophage]

Since I've had it, my TR-707 has been begging for new samples. I think
the toms have a nice "boinginess" to them, but the sounds are mostly
crap. Gets tiresome, which is really too bad as I think that the 707 is
really a joy to program!

I had done a wee bit of resrearch on the scarce 61256 SRAMs which the
stock six-bit samples are stored. The ICs appear to had been quickly
supplanted by the slightly faster 62256. Slammin news is that I just
bought my first EPROM programmer! Willem-type, decent support and quite
cheep. I've wanted to burn EPROMs since I was like 10 years old. I
found some cheep 62256 SRAMs, so of course I am thinking about
desoldering the built-in SRAMs and trying to read the contents.

Why I hesitate? I am in the process of doing a few other mods to the
unit. More so, I was reading on Colin Fraser's site that in the
(indentically implemented) 909 cymbals, that Roland had decided to
completely redo which data and address lines were which- also swapping
the "write enable" pin (?). So, for not really knowing exactly what I
am doing in reading, writing, interpreting, etc the data- I am a little
hesitant. I might even make new sockets so I can use 27256 EPROMs
instead. 

What would make all of this much easier is the TR-707 schematic. I have
a 1 MB archive of TIF scanned pages... the same zip as on Dave
Magnuson's site, and the Yahoo TR-707 group. The problem is that the
scans are so small that the type is unreadable. Sure, they've been good
for getting "the big picture" of how the 707 works, but now I need to
be able to read which compents are which, and which pins are which.

I am sure I can grind my way through this, but if somebody can point me
out to a legible copy of the 707 schemo, I'd be ultra-psyched and
extremely grateful! 

Other mods I am doing in the meanwhile are a 100k pot for coarse tempo
control (done), and a board of VCOs for individual sample-rate control.
Whew... back to the garage!
CJ


	
		
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