Vintage Synth Repair

I really wouldn't worry then..these things are
designed to run within a range of voltages...ie
tolerance +-20%.. the +15 -15 is for the Op amps I
would have thought..they'll be quite happy with a nice
a current at 14.4v. The transistors could make a
difference yes but I doubt they actually will..the
main contenders are the caps and the regulator which
you've already changed.

Put it back together is my advice... :o)

Good luck, Phil.





--- gil_we <gil_we@...> wrote:

> Yep, no actual problem with the synth itself. I just
> feel that it 
> would be generally better for the circuit to run on
> the correct 
> volatges. It could be a little distorted as well I
> think....
> The voltages are read when PS is not connected to
> the other units.
> 
> Will reaplcing the transistors do the trick ?
> 
> 
> 
> 
> --- In vintagesynthrepair@yahoogroups.com, Philip
> <eggwheatis@...> 
> wrote:
> >
> > 14.4 volts I would say wouldn't cause you much of
> a
> > problem anyway. It's ususally not critical. If it
> was
> > the the +5 we are talking about then it would be
> > different. It's common for psu voltages not to be
> > exact even from brand new. Do you actually have a
> > problem with the keyboard? 
> > 
> > If there is no problem with the keyboard I'd just
> put
> > it back together and leave it.
> > 
> > If there really is a problem with the synth then
> maybe
> > swap out the two transistors. If still a problem
> then
> > it's probably not the PSU but something in the
> synth
> > circuit that uses the +15-15 dragging the PSU
> down..
> > 
> > 
> > 
> > 
> > --- gil_we <gil_we@...> wrote:
> > 
> > > I've just refurbished my JX8P's power supply
> unit,
> > > replacing all caps. I check the voltages and see
> > > +14.40v and -14.40v instead of -15v and +15v.
> > > 
> > > The schematics shows a M5230L dual tracking
> > > regulator, two 
> > > transistors and an array of resistors.
> > > 
> > > So far I replaced the regulator to no avail,
> > > and verified the correct values of the various
> high
> > > precision 
> > > resisotrs in the circuit, which are found to be
> ol.
> > > 
> > > I'm trying to figure out what could be causing
> this
> > > problem,
> > > can anyone help ?....
> > > 
> > > Here's JX8P power supply schematics:
> > >
> >
>
http://www.fileden.com/files/2006/10/13/285304/jx8p%20ps.JPG
> > > 
> > > ..and here's M5230L datasheet:
> > >
> > 
>
http://www.ortodoxism.ro/datasheets/MitsubishiElectricCorporation/mXqy
> > > yxt.pdf
> > > 
> > > Thanks in advance !
> > > 
> > > 
> > > 
> > 
> > 
> > 
> >      
>
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> 
> 
> 



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