To: vintagesynthrepair@yahoogroups.com
From: gil_we@...
Date: Mon, 3 Mar 2008 12:25:27 +0000
Subject: [vintagesynthrepair] Re: JX8P +15v and -15v voltages are wrong...
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 ...>
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 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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