Vintage Synth Repair

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.

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.

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.
>

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
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
>     
>             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.skycraft surplus.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.
> 
> >
>

actually, that's still helpful news. i wanted to have a spare 15/-15
"bench" PSU for testing, anyway, so i might still replace the parts on
the old PSU. so, the tip120 is equivalent to mje1100, do you know what
the mje1090 is equivalent to? and sorry, i hate to ask this, but do
you know the equivalent to the 748 voltage regulator? the mouser part
comes up as 8 pin, which isnt right. thanks alot for the help,
mariano! this is actually good news!



--- In vintagesynthrepair@yahoogroups.com, mariano elizalde
<syntherman@...> wrote:
>
> sour note.... seems feasible to replace those transistors with the
TI equivalents like the tip120, only has to reverse the leads since
their pinout is different, something like TIP120 ECB while the old
mje1100 is BCE... hardly hard to do...the tip's run for $ 0.69 locally
at BG MICRO... this I just found out last night... wish I had known
before you spend your money there...sorry... :(
> 
> --- On Wed, 9/24/08, 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: Wednesday, September 24, 2008, 8:31 AM
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
>     
>             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.
>

Anyone point me in right direction to repair distorted output on all  
outs- headphone, L & R.  Distortion lasts until sound decay stops.

Cleaned contacts and surface of output board.  I'm not a tech, but a  
player, but this seems like should be a simple fix.

Don't have schematics and can't find any previous posts on this  
problem.  TIA!

Hi all,
Is there anyone here who has Oberheim OB-8 knobs they are willing to 
sell/trade?
I need three knobs for a unit I´m having in for service.

Terje Winther
terje.winther@...
http://www.wintherstormer.no/

..tell you what, maybe I can locate a 14 pin lm748 locally, have some contacts :]...  if I can I'll pass it to you, respect the tip series, the tip125 ($0.89 at BG MICRO ) is the complementary to the tip120 ($0.79... lied to you on previous post) but like I said, their pinout I believe is reversed respect to the original ones, also the transistor case is slightly different and they might need a different mounting method since their collectors are tied to the metal flange.  will check tonite some of my old manuals on transistors to make sure. is there an image of the power supply showing the components and the coper traces? like a component layout or something like it that perhaps you can upload to the archives... that would help to troubleshoot further. I.m looking n alternate part for the opamp meantime...

I don't own a D50 and have not seen the D50 service manual (there doesn't seem to be a copy floating around online), so don't trust this to be correct or even relevant, it's just my best guess.

There may be an MSB adjustment for the D50's DAC (I know the JD-800 has this).  If this is off, there will be a discontinuity at every zero-crossing, producing distortion at any signal level.  There will be a trimmer for this (if it's adjustable), but you shouldn't just go arbitrarily turning trimmers to find it.

You may want to record the D50's output to your computer so you can observe the waveform and get a better idea of what's going on.

________________________________
> To: vintagesynthrepair@yahoogroups.com
> From: adam@...
> Date: Thu, 25 Sep 2008 12:32:45 -0500
> Subject: [vintagesynthrepair] Roland D-50 Output Distorted
> 
> 
> Anyone point me in right direction to repair distorted output on all
> outs- headphone, L & R. Distortion lasts until sound decay stops.
> 
> Cleaned contacts and surface of output board. I'm not a tech, but a
> player, but this seems like should be a simple fix.
> 
> Don't have schematics and can't find any previous posts on this
> problem. TIA!
> 
> 

_________________________________________________________________
Stay up to date on your PC, the Web, and your mobile phone with Windows Live.
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never mind on the power supply image... i knew i had a comy of the service manual somehwere...

--- On Thu, 9/25/08, mariano elizalde <syntherman@yahoo.com> wrote:
 is there an image of the power supply showing the components and the coper traces? like a component layout or something like it that perhaps you can upload to the archives... that would help to troubleshoot further. I.m looking n alternate part for the opamp meantime...

 
_

resurrecting this old thread.

Did anyone ever figure out the best way of mounting the TIP20/TIP25 darlington pair in the arp 2600? They use case style TO-220, whereas the originals (MJE1100 and MJE1090) use TO-126. One is BCE and the other ECB. You cannot just flip them around since they are used for mounting the board as well.

Curious how others handled this. Did you cut traces and rewire or use some other method?

Thanks,

DT



--- In vintagesynthrepair@yahoogroups.com, syntherman <syntherman@...> wrote:

>
> never mind on the power supply image... i knew i had a comy of the service manual somehwere...
> 
> --- On Thu, 9/25/08, mariano elizalde <syntherman@...> wrote:
>  is there an image of the power supply showing the components and the coper traces? like a component layout or something like it that perhaps you can upload to the archives... that would help to troubleshoot further. I.m looking n alternate part for the opamp meantime...
> 
>  
> _
>