Puddin' Man wrote in message
...
On Thu, 13 Dec 2007 01:11:59 GMT, "Arfa Daily"
wrote:
"Puddin' Man" wrote in message
.. .
On Wed, 12 Dec 2007 15:42:10 -0600, jakdedert
wrote:
You need to find the main power supply board, and trace forward from
where there. That board (or portion of the main circuit board where
the
DC adapter connects) is where the excess voltage is regulated down to a
level that the actual circuits use.
Power supply board:
Takes input from batt. or converter
Connections:
Black wire - screws to alum. kb frame
"to HP" - 3 element, goes to speaker
"to DM" - 4 element, goes to 1684 PN1 (lg. board)
elements are labeled DG +5D AG +5A
+5D and +5A measure 5v DC to black wire
"to SW" - 8 element, goes to switch/volume board
elements are labeled E 5v B T M S E E
M measures 15v DC to black wire
The two large boards (2 x 12+ ") are labeled 1684 PN1 and 1684 PN2
with markings for the voicings, various effects.
Any help?
Thx,
P
"+5D" will be the 5v digital supply - ie the 5v supply for the digital
electronics, and "+5A" will be the 5v analogue supply. "DG" and "AG" are
the
corresponding digital and analogue ground returns for those two supplies,
so
will be the references to measure the supplies against.
That's a big help. I had no idea how they code such stuff.
You really need to
be able to measure the +5D supply with a reasonable amount of accuracy -
to
at least 0.05v.
To what extent will such an accurate measuring device empty my po' wallet?
Goes without saying that if I get 5v from +5D when it plays and 0v when
it freezes, I've likely found my problem?
Thanks,
P
For some odd reason it is often difficult to
find a 0 ground point on music keyboards.
Usually the battery negative is usable for that.
Unpowered of course
I would undo and remake any ribbon connections and closely inspect all
surface mount chips with a powerfull magnifying glass and bright light ,
followed by looking at all solder joints.
then powered
Use an empty plastic ball point pen barrel to push all chips, tap other
lumps ,waggle wires etc while powered up to see if anything changes , with a
note engaged by sticky tape.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/