Vintage Synth Repair

Ok, thanks buddies ;)

It just courious me why the voltage would drop anyway....





--- In vintagesynthrepair@yahoogroups.com, Scott Nordlund <gsn10@...> 
wrote:
>
> 
> It's only 4% lower than the specified voltage- it really doesn't 
matter.  It could just be a result of component tolerance.  Probably 
any skilled designer wouldn't be pushing signal levels so much that a 
0.4V drop would cause any distortion.  I think you're wasting your 
time to try to "fix" this.
> 
> 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...
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>             Yep, no actual problem with the synth itself. I just 
feel that it 
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> would be generally better for the circuit to run on the correct 
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> volatges. It could be a little distorted as well I think....
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> The voltages are read when PS is not connected to the other units.
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> Will reaplcing the transistors do the trick ?
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> --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@> 
> 
> wrote:
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> >
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> > 14.4 volts I would say wouldn't cause you much of a
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> > problem anyway. It's ususally not critical. If it was
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> > the the +5 we are talking about then it would be
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> > different. It's common for psu voltages not to be
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> > exact even from brand new. Do you actually have a
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> > problem with the keyboard? 
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> > If there is no problem with the keyboard I'd just put
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> > it back together and leave it.
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> > 
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> > If there really is a problem with the synth then maybe
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> > swap out the two transistors. If still a problem then
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> > it's probably not the PSU but something in the synth
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> > circuit that uses the +15-15 dragging the PSU down..
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> > --- gil_we <gil_we@> wrote:
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> > > I've just refurbished my JX8P's power supply unit,
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> > > replacing all caps. I check the voltages and see
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> > > +14.40v and -14.40v instead of -15v and +15v.
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> > > 
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> > > The schematics shows a M5230L dual tracking
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> > > regulator, two 
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> > > transistors and an array of resistors.
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> > > 
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> > > So far I replaced the regulator to no avail,
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> > > and verified the correct values of the various high
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> > > precision 
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> > > resisotrs in the circuit, which are found to be ol.
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> > > 
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> > > I'm trying to figure out what could be causing this
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> > > problem,
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> > > can anyone help ?....
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> > > 
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> > > Here's JX8P power supply schematics:
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> > >
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> > http://www.fileden.com/files/2006/10/13/285304/jx8p%20ps.JPG
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> > > 
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> > > ..and here's M5230L datasheet:
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> > >
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http://www.ortodoxism.ro/datasheets/MitsubishiElectricCorporation/mXqy
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> > > yxt.pdf
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> > > 
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> > > Thanks in advance !
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