Vintage Synth Repair

oh, i'd never TOSS it. but with the mje1100's running $30/pop, its not
something i think is sensible to sink a bunch of money into. i'll
definitely hold onto it, just not sure how much use i'll get out of
it, assuming the new PSU tunes up fine and works.



--- In vintagesynthrepair@yahoogroups.com, mariano elizalde
<syntherman@...> wrote:
>
> ... before you throw away the old power supply, you might still
consider repairing it... 
> 
> --- On Tue, 9/23/08, r_j_d_2.phila <r_j_d_2.phila@...> wrote:
> From: r_j_d_2.phila <r_j_d_2.phila@...>
> Subject: [vintagesynthrepair] Re: ARP 2600 PSU, pt. 2. electric
boogaloo.
> To: vintagesynthrepair@yahoogroups.com
> Date: Tuesday, September 23, 2008, 8:40 PM
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>     
>             thanks alot for that, i appreciate it. i replaced the
mje1100 and mje
> 
> 1090, and socketed the voltage regulators 723/748. i put my ear up
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> next to the PSU as it was crackling, and im about 80% sure it was
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> coming from the mje 1100.
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> 
> 
> i've ordered the 1.5A power-one supply just to be safe, so once i
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> calibrate it and wire up the leads, i should know if the problem was
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> in the synth or PSU. thanks much-rj
> 
> 
> 
> --- In vintagesynthrepair@ yahoogroups. com, mariano elizalde
> 
> <syntherman@ ...> wrote:
> 
> >
> 
> > Hello there;
> 
> >   the original power supply is current limited to about 600 mA so if
> 
> you drop a power supply with a rated capacity of say 800 mA (0.8A) you
> 
> should be fine,*but* you still might want to make sure the old power
> 
> supply is not failing because trouble inside the synth, but maybe
> 
> because it is old.  someone posted a link to a power supply being sold
> 
> as  surplus  very cheap. let me repost the link...
> 
> http://www.skycraft surplus.com/ index.asp? PageAction= VIEWPROD&
ProdID=439 
> 
> I am familiar with this one, I have something like that here so let me
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> know if you may need further assistance on rewiring it.  
> 
> > 
> 
> >  and yes, all those power supplies you refer to are linear type,
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> they should be fine provided the synth's electronics are all ok.
> 
> > 
> 
> > There should be a substitute for these transistors, but then again,
> 
> sounds more economical to replace the power supply all together.
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> > 
> 
> > out of curiosity, what parts did you replace ?
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> > 
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> > 
> 
> > --- On Tue, 9/23/08, r_j_d_2.phila <r_j_d_2.phila@ ...> wrote:
> 
> > From: r_j_d_2.phila <r_j_d_2.phila@ ...>
> 
> > Subject: [vintagesynthrepair ] ARP 2600 PSU, pt. 2. electric boogaloo.
> 
> > To: vintagesynthrepair@ yahoogroups. com
> 
> > Date: Tuesday, September 23, 2008, 3:56 PM
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> >     
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> >             so my parts came in today, and i got to soldering.
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> disconnected the
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> > synth, dropped in the new power transistors, double checked my work,
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> > 
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> > made sure no solder bridged any leads. upon powering up, i hear a
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> > 
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> > crackling, which i later isolated to what i believe is the
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> > 
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> > MJE1100(+15V power transistor). on a meter, its jumping all over the
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> > place, from 4V to 12V. neg voltage is essentially mirroring this. 
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> > im assuming i got a bad MJE1100. but seeing as how the part is $30 and
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> > obsolete, it seems like it makes more sense for me to just buy a new
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> > 
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> > linear +15/-15 PSU and drop it in. but this brings up my original
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> > 
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> > issue: current draw. the only things i have to go on here are that the
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> > 
> 
> > original fuse, and original transformer, were both rated for .5A. now
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> > i would ASSUME that the HAA15-.8-AG, a .8A rated PSU from power-one:
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> > http://www.power- one.com/cgi- bin/acdc_ search.cgi? volts_1=15&
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> volts_2=- 15&ref=linear& lid=37448& x=80&y=6& LINEAR=f
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> > would be sufficient, but i dont know what the + side vs. - side
draw is
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> > of the ARP. furthermore, would going for the next size up, the 1.5A,
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> > make sense, or is there any issue with PSU's seeing a lot less of a
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> > load than they are rated for? thanks alot for any advice, folks.-rj
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> > ps-on the subject of digital power supply replacing the old analog, i
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> > 
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> > believe these are all analog PSU's. please correct me if im wrong.
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> >
>