Vintage Synth Repair

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@yahoo.com>
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.