PLAN B analog blog

All,

We have discovered an error in the programming of the Model 28 Tapper.
 There's a fix - please read on.

There are two input pins on the microprocessor which determine which
of the three SERIAL output states (quarter note/eight/triplet) are
passed through.  These are fed by two external window comparators. One
input gives indication that the voltage at the SELECT INPUT is over
2.5 volts, one if it's between 2.5 and 5.5 volts.

Well, there was a mis-communication and it seems either I told my
programmer the pins in the wrong order, or he reversed it - that
doesn't matter - the issue is they are reversed in the first 15 units
shipped.  Everything does it's thing - but because the info the micro
receives is not coded correctly, the voltage levels required to do
that decoding are not as outloined in our spec sheet.

I do not have a database of who purchases our products from our
dealers.  What I am asking you to do is test this function and if it
is determined that they do NOT behave as outlined in the M28 product
page on our site, that you return U1 -- the 20 pin dip IC labeled
either ATMEL AT89C2051-12 or -24 to us and we will reprogram it and
send it back immediately.  There are letters after the -12 and -24 -
those don't matter, U1 is the bugger that need to be reprogrammed.

The part can easily be removed from it's socket through the use of
either a chip-puller or a small flat-blade screwdriver.

The address to send that is:

Electro-Acoustic Research
10870 Camarillo St.
Toluca Lake, CA
91602

Please pardon this error, we wil do everything required to get you
back on the road as quickly as possible.

- P