Vintage Synth Repair

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
next to the PSU as it was crackling, and im about 80% sure it was
coming from the mje 1100.

i've ordered the 1.5A power-one supply just to be safe, so once i
calibrate it and wire up the leads, i should know if the problem was
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.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=439 
I am familiar with this one, I have something like that here so let me
know if you may need further assistance on rewiring it.  
> 
>  and yes, all those power supplies you refer to are linear type,
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.
> 
> out of curiosity, what parts did you replace ?
> 
> 
> --- 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
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
>     
>             so my parts came in today, and i got to soldering.
disconnected the
> 
> synth, dropped in the new power transistors, double checked my work,
> 
> made sure no solder bridged any leads. upon powering up, i hear a
> 
> crackling, which i later isolated to what i believe is the
> 
> MJE1100(+15V power transistor). on a meter, its jumping all over the
> 
> place, from 4V to 12V. neg voltage is essentially mirroring this. 
> 
> 
> 
> im assuming i got a bad MJE1100. but seeing as how the part is $30 and
> 
> obsolete, it seems like it makes more sense for me to just buy a new
> 
> linear +15/-15 PSU and drop it in. but this brings up my original
> 
> issue: current draw. the only things i have to go on here are that the
> 
> original fuse, and original transformer, were both rated for .5A. now
> 
> i would ASSUME that the HAA15-.8-AG, a .8A rated PSU from power-one:
> 
> 
> 
> http://www.power- one.com/cgi- bin/acdc_ search.cgi? volts_1=15&
volts_2=- 15&ref=linear& lid=37448& x=80&y=6& LINEAR=f
> 
> 
> 
> would be sufficient, but i dont know what the + side vs. - side draw is
> 
> of the ARP. furthermore, would going for the next size up, the 1.5A,
> 
> make sense, or is there any issue with PSU's seeing a lot less of a
> 
> load than they are rated for? thanks alot for any advice, folks.-rj
> 
> 
> 
> ps-on the subject of digital power supply replacing the old analog, i
> 
> believe these are all analog PSU's. please correct me if im wrong.
>