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Re: EDP Repairs

sorry you didnt see this before


your repair facility (if its not Gibson) would probably like this info

Good luck


and here is another quote of Kim for some other thermal problem the
plexis can have (didnt make the mod yet....)

Kim Flint wrote

If you are comfortable with a soldering iron and a bit of tinkering, I
a good suggestion that should fix the problem. Oberheim has been doing
on all new units for the past year or so, and it really is a nice

The basic problem is heat in that part where we cut the pin (U12, the
ADC0804). When it gets too hot it causes this odd error with reading the
Undo switch. That particular pin was connected wrong in the original
and caused the part to get hot much faster and cause this error, so
the pin usually fixes the problem. However, it's still possible for the
part to screw up if it gets hot enough. Older units had some parts which
ran very hot, and tended to overheat the whole unit if the ventilation
wasn't good or it was a particularly hot day. (since it's summer, this
could be your trouble.) The worst offenders are the two linear +5V
regulators for the digital circuitry, U28 and U40, which you will find
the back, screwed to a heat sink and the chassis. It turns out there are
replacements for these parts which generate practically no heat at all,
making the whole situation much better. So we can swap these in and you
should be a happy looper with a room temperature echoplex!

These parts were considered too costly for use in the original
echoplexes, but are not really all that expensive. Later, they decided
was worth it to use them so customers wouldn't have these problems, a

We can change the two +5V linear regulators to switching regulators. In
Digikey there is a great part for this, the Power Trends
(http://www.powertrends.com/)  PT5101N 5V switching regulator. You can
actually use one of these to replace both of the linear regulators, and
works just fine. (I've had a unit using one of these for years.)

You need to take the PCB out of the chassis to do it. What you want to
is unscrew the regulators from the chassis and the heatsink. Desolder
remove both U28 and U40, the linear regs. Take the heat sink out
since it will be in the way, and you won't need it anymore.

Solder the PT5101 into one of the regulator spots (the left one is a
choice). The PT5101 is pin compatible with the linear regs, so there
be no trouble with that. Now solder a wire from it's output pin (pin 3,
the right when looking at the front of the part) to the output hole (pin
again) for the other regulator location. This way the PT5101 will be
supplying power for both the +5V rails the old regulators powered. Now
power it up and make sure it works! You should see it runs practically
room temperature now, and hopefully that cures the trouble.


Hans Lindauer wrote:
> Howdy all-
> Does anybody have an idea as to the current turnaround time on EDP 
> I bought a used one two months ago and discovered that it was defective, 
> the shop sent it in for repair.  The thing would work for fifteen minutes
> just fine, and then the Undo would activate Record.  Which is fine if you
> never make a mistake...  I figure it's been at the EDP repair facility 
> about a month now, and I'm getting kind of antsy.
> Hans Lindauer
> Engineer, Music Man R&D
> Ernie Ball, Inc.
> hans@ernieball.com