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Subject: Re: [korgpolyex] my Hawk-800

From: Michael Hawkins <korgpolyex800@...>
Date: 2008-12-28

I knew I couldn't escape the critical eye of atom!

1) I don't think the kit is quite as hard as atom is making it out to be but, I am a littled biased. Yes, a professional desoldering station is probably the most important tool that I would recommend to do the job.

2) the supplied IC29 is a 40H138 or 74HC138. they are one and the same just different part number from different manufacturers.

3) the jumper on the back will not be required on board rev 1.4

4) if you don't pull the jumper wires taught so that they are flat then yes, the IC sockets can sit up slightly. But if you solder one end of each jumper and then feed the other end through the second hole and then use a pair of long nose pliers to strain the jumper wire, you can end up with a very flat jumper. Those sockets are high quality but they do require a firm push to ensure that the chips are fully seated.

5) yes, the diodes and battery holder will be completely eliminated from board rev 1.4

6) yes, the decoupling capacitors should be one per chip. I will have another look at that for board rev 1.4

7) if you got a cable with a red line on it, you just got lucky. You should not be using those red marks to mean anything. I make (and test) the cables by hand. I bought a 100 meter roll of 50 wide flat ribbon. I then splice off what is needed to assemble the ribbon cable units.

8) now if you had done a proper inventory of your parts you would have found the missing cap sooner. Perhaps I'll drop those two caps onto into a little baggie just to keep them from getting lost.

9) I guess I figured anyone alive today that owns a Poly ought to know how to get a syexe file into it. :-) But I didn't think that there would be ppl out there that don't have a computer of any kind or brand to use to do it.

10) Eventually I will start selling fully modified Poly's on ebay. But for now, I am still trying to finish the software. It's a long, lonely road.

Do let us know what you think of it all once you get past "FLASH" mode.

Mike.


From: Atom Smasher <atom@...>
To: korgpolyex@yahoogroups.com
Sent: Sunday, December 28, 2008 4:56:22 AM
Subject: [korgpolyex] my Hawk-800, progress report

this kit is totally NOT for people who don't have experience with
electronic kit building, or preferably electronic repair. i'm so glad that
i own a solder-sucker!

and now for a critical review of what i've done so far...

i decided to destructively remove IC29 (on my board it was a CMOS 40H138,
not a TTL 74138 as described in the docs) in order to minimize the risk of
damaging the PCB.

my Hawk PCB is labeled rev 1.3, and some of the jumpers are a bit closer
than i would have liked them, but i had no problem with the "small" solder
pads. i was also surprised that i needed a jumper on the back.

the docs show the chip socket for the header-cable being different than
the other chip sockets; all of my chip sockets look like the type used for
the header, and some of them hit the jumpers and don't sit flush against
the board, but they're close enough. some of the chips don't feel like
they're seated 100%, so i'll probably hit them with some hot-glue before i
call it finished.

i noticed that D2 is only used to keep a backwards battery from damaging
anything, so i left that out along with the battery holder. i might wind
up using the battery holder in something else.

C1 seems to be used to keep the power lines to the chips clean... but is
it really effective when there's only one of them, and at the opposite end
of the board from some of the chips it's protecting? i thought best
practice was one cap per chip, located as close as practical to each
chip...?

also the ribbon cables... i was expecting the red mark to be towards pin
1; the larger cable had it on the other side, the smaller cable didn't
have a red mark.

oh... when i got to soldering the two capacitors to the board i could only
find one. i searched and dug through the kit to no avail. i ran to jaycar
just before they closed for the day, got a pack of two, got back, put the
second capacitor on the board, and as soon as i looked up i saw the
missing cap, stuck to the tape on one of the IC tubes.

can i remove the battery from the EX800 main-board?

right now i've got it at the point where it powers up and says "FLASH".
since my computers and my synths don't talk to each other, getting the OS
loaded will be a non-trivial task for me. in the meantime i'll be looking
at 1U rack enclosures. i'll hold off on the AtomaHawk until i have a
better idea of the enclosure situation.

does anyone have any fresh leads for a 1U keypad?

all in all, it went smooth, and i probably spent 3-4 hours on the bench
(not including my jaycar trip). one of the things that cost me time was
not having a printout of the docs, so i had to keep getting up and looking
at the computer, going back and forth.

i would highly suggest that anyone without the experience to do this
either find a guitar/amp/electron ics repair shop that will quote a price
(or, if they insist on charging by the hour, at least get them to give you
a maximum charge), or work out with someone on the list to do the mod.
it's not for the inexperienced or the faint-hearted. another option for
having it done ~might~ be an electronics shop at a local vo-tech or trade
school... they might be able to assign it to a student as an extra-credit
project, or hook you up with a student who is ∗capable∗ of doing it as a
side project for a few bucks.

for those on the list who are comfortable with doing the kit, i'm curious
how lucrative it might be to sell completed kits on evil-bay...?

--
...atom

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