Vintage Synth Repair

Rob, you are correct. I meant to add that the +ve terminal is the centre connector on the plug.

Thanks
Royce

--- In vintagesynthrepair@yahoogroups.com, "robwilljy" <robwilljy@...> wrote:
>
> 
> 
> Royce and Brian...you are obviously profesionals that know a lot better than me about all this but I always warn folk about the dangers of using unregulated power supplies into (especially) low power kit as the actual measured voltage can be much higher than specified.
> 
> Also the obvious problem (my son fried a Roland keyboard by putting in a Yamaha power supply) of the wrong polarity power supply. Its amazing that Roland and Yamaha took the opposite paths with polarity, while using identical plugs!
> 
> And...almost too ambarassed to mention this, but it does happen!...putting an AC adapter into a DC device...again the manufacturers often use the same type of plug. 
> 
> Nice to get your info Brian...I Googled your details and will add you to my "little black book" for keyboard repairs..yes? Crawley UK area?
> 
> --- In vintagesynthrepair@yahoogroups.com, "Brian" <brian@> wrote:
> >
> > Hi Royce
> > 
> >  
> > 
> > No problem.  I have access to the entire Yamaha on-line database, plus I
> > carry a 3 CD set of schematics.  I am a professional engineer repairing, to
> > component level, electronic keyboards and guitar amps.  Similarly I have
> > access to the Kawai, Fender and Marshall databases.  Regrettably many of the
> > other manufacturers don't treat me as well!!
> > 
> >  
> > 
> > Your power supply schematic was lifted direct from Yamaha hence the
> > excellent scan.
> > 
> >  
> > 
> > Yes I would say that 12V should be OK, but as previously suggested I would
> > check on the temperature of the various regulator components to ensure that
> > things are not over-heating.
> > 
> >  
> > 
> > As an example of this my local church has a Yamaha P80.  The power unit
> > supplied gave a lot of trouble and I repaired it on several occasions.  Then
> > the inevitable happened I setup the unit for the pianist one Sunday morning
> > only find that the power unit had failed.  I rushed back to the workshop and
> > picked up a selection of spare power supplies and plugged in a Kawai unit
> > that gave out 20V, whereas the Yamaha unit only gave 12V.  Two years on and
> > all is still fine!
> > 
> >  
> > 
> > Regards
> > 
> > Brian G3OYU
> > 
> >  
> > 
> > From: vintagesynthrepair@yahoogroups.com
> > [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Royce
> > Sent: 25 February 2010 9:38 AM
> > To: vintagesynthrepair@yahoogroups.com
> > Subject: [vintagesynthrepair] Re: Yamaha TG33 power supply
> > 
> >  
> > 
> >   
> > 
> > Thanks Brian.
> > What a great scan. I wish I could get my ccts to scan that well.
> > 
> > Looks like there is a 5V reg for the digital and the full voltage is sent to
> > power some OpAmps 
> > As well there is a split off regulated with a 9.1V 1A zenner but most of the
> > load is passed through a transistor. I assume it is on a heat sink.
> > 
> > Did I miss anything?
> > 
> > So 12V should be OK.
> > 
> > Thanks again
> > Royce
> > 
> > --- In vintagesynthrepair@yahoogroups.com
> > <mailto:vintagesynthrepair%40yahoogroups.com> , "Brian" <brian@> wrote:
> > >
> > > I can offer you a copy of the whole cct, however you should be OK with 12V
> > > but you may want to check the operating temperatures of the regulator
> > ccts.
> > > 
> > > 
> > > 
> > > If the Yahoo system removes the attachment contact me off list.
> > > 
> > > 
> > > 
> > > Regards
> > > 
> > > Brian G3OYU
> > >
> >
>