Vintage Synth Repair

Hello,

I have a Roland A-37 MIDI Keyboard Controller that doesn't power up.
I actually bought this at an estate sale to resell --- but there was no joy when I got it home and plugged in a power supply.

I've seen numerous other ones just like this for sale online ---"looks like new but won't power-up"

I'm guessing there might be a common fix --- such as an inline fuse.
Anyone know?

Thanks,
Sam

Thanks Z3

Perhaps next weekend's project.

Best,
Sam

--- In vintagesynthrepair@yahoogroups.com, "z3sound" <z3sound@...> wrote:
>
 unplug Cn3 connector that

> go to CPU board just to be sure there is no short on that board, then
> check if you have supply at pin 1 of Q3 (emitter)or at + of capacitor
> C2if no voltage you may have a defective part in the power supply board
> check D1 ,Q3 or the zener diode D5 ,i have put the power supply
> schematic in  the file sectionhope it will helpif you need it i have the
> complete A37 schematicZ3
> 
>

I'm having problems with an SH 2000 , it has this hi pitch squeal whenever I play a note.
It's in pitch so it's not some random noise.
It's still there when I turn of all presets ?

PSU is recapped.

Any ideas?

Thanks
Arnar
RVK
Iceland.

sounds like filter is set to high resonance as its in pitch and is tracking pitch

see if you can adjust the resonance and if it has any effect

  ----- Original Message ----- 
  From: plat@... 
  To: vintagesynthrepair@yahoogroups.com 
  Sent: Monday, November 28, 2011 11:44 AM
  Subject: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000


    

  I'm having problems with an SH 2000 , it has this hi pitch squeal whenever I play a note.
  It's in pitch so it's not some random noise.
  It's still there when I turn of all presets ?

  PSU is recapped.

  Any ideas?

  Thanks
  Arnar
  RVK
  Iceland.

I will check but I don't think its that .
Looks fuzzy on the scope , maybe squeal is not the right word ..more like a whine with noise.

Thanks!

Arnar

----- Original Message -----
Frá: "jammie" <jammie.emma@blueyonder.co.uk>
Til: vintagesynthrepair@yahoogroups.com
Sent: Mánudagur, 28. Nóvember, 2011 03:53:15
Efni: Re: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000






 
sounds like filter is set to high resonance as its in pitch and is tracking pitch 

see if you can adjust the resonance and if it has any effect 


----- Original Message ----- 
From: plat@simnet.is 
To: vintagesynthrepair@yahoogroups.com 
Sent: Monday, November 28, 2011 11:44 AM 
Subject: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000 





I'm having problems with an SH 2000 , it has this hi pitch squeal whenever I play a note. 
It's in pitch so it's not some random noise. 
It's still there when I turn of all presets ? 

PSU is recapped. 

Any ideas? 

Thanks 
Arnar 
RVK 
Iceland.

Hi Arnar
First monitor with the scope the supply +15 and -15 in ac mode to see if any noise from the power supply
Do you have that fuzzy look directly at the output of the VCO (collector of Q105 or pin 1 of connector)VCO board ?? If not you have to track the signal to see where the noise begin to show ,you can also check the output of the divider board VG-7 check pin 20 .next the output of the VCF (push VCF Man tab ,put the cutoff fully clockwise and the resonance to zero) pin 9 of VCF board. if no fuzzy thing move to the VCA out pin of the same board. Hope will help.If do don't have the schematic I can post it
Z3

--- In vintagesynthrepair@yahoogroups.com, "plat@..." wrote:
>
> I will check but I don't think its that .
> Looks fuzzy on the scope , maybe squeal is not the right word ..more like a whine with noise.
>
> Thanks!
>
> Arnar
>
>
>
> ----- Original Message -----
> Frá: "jammie" jammie.emma@...
> Til: vintagesynthrepair@yahoogroups.com
> Sent: Mánudagur, 28. Nóvember, 2011 03:53:15
> Efni: Re: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000
>
>
>
>
>
>
> 
> sounds like filter is set to high resonance as its in pitch and is tracking pitch
>
> see if you can adjust the resonance and if it has any effect
>
>
> ----- Original Message -----
> From: plat@...
> To: vintagesynthrepair@yahoogroups.com
> Sent: Monday, November 28, 2011 11:44 AM
> Subject: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000
>
>;
>
>
>
> I'm having problems with an SH 2000 , it has this hi pitch squeal whenever I play a note.
> It's in pitch so it's not some random noise.
> It's still there when I turn of all presets ?
>
> PSU is recapped.
>
> Any ideas?
>
> Thanks
> Arnar
> RVK
> Iceland.
>

Taking another look using your directions .

Thanks !


----- Original Message -----
Frá: "z3sound" <z3sound@...>
Til: vintagesynthrepair@yahoogroups.com
Sent: Mánudagur, 28. Nóvember, 2011 09:44:31
Efni: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000








Hi Arnar 
First monitor with the scope the supply +15 and -15 in ac mode to see if any noise from the power supply 
Do you have that fuzzy look directly at the output of the VCO (collector of Q105 or pin 1 of connector)VCO board ?? If not you have to track the signal to see where the noise begin to show ,you can also check the output of the divider board VG-7 check pin 20 .next the output of the VCF (push VCF Man tab ,put the cutoff fully clockwise and the resonance to zero) pin 9 of VCF board. if no fuzzy thing move to the VCA out pin of the same board. Hope will help. If do don't have the schematic I can post it 
Z3 

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

> 
> I will check but I don't think its that . 
> Looks fuzzy on the scope , maybe squeal is not the right word ..more like a whine with noise. 
> 
> Thanks! 
> 
> Arnar 
> 
> 
> 
> ----- Original Message ----- 
> Frá: "jammie" jammie.emma@... 
> Til: vintagesynthrepair@yahoogroups.com 
> Sent: Mánudagur, 28. Nóvember, 2011 03:53:15 
> Efni: Re: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000 
> 
> 
> 
> 
> 
> 
>  
> sounds like filter is set to high resonance as its in pitch and is tracking pitch 
> 
> see if you can adjust the resonance and if it has any effect 
> 
> 
> ----- Original Message ----- 
> From: plat@... 
> To: vintagesynthrepair@yahoogroups.com 
> Sent: Monday, November 28, 2011 11:44 AM 
> Subject: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000 
> 
> 
> 
> 
> 
> I'm having problems with an SH 2000 , it has this hi pitch squeal whenever I play a note. 
> It's in pitch so it's not some random noise. 
> It's still there when I turn of all presets ? 
> 
> PSU is recapped. 
> 
> Any ideas? 
> 
> Thanks 
> Arnar 
> RVK 
> Iceland. 
>

>I'm having problems with an SH 2000 , it has this hi pitch squeal whenever I play a note.

>It's in pitch so it's not some random noise.

>It's still there when I turn of all presets ?

The sawtooth wave is made by mixing octave divided square waves. Maybe one of the higher octaves is coming through when it shouldn't.

tonight i have taken out my own Sh 2000 to take some measurement  to try to help you find your  noise problem ...but surprise with all preset off i got the same noise and in high pitch tone (in pitch with the keyboard),it is like the top oscillator VCO bleeding though the the supply. but when i hit a preset tab everything sound ok  without any noise , and i thing it is perfectly normal to hear the noise when no preset is activated . i have try to undo some of the adjustment on the VCF/VCA board, and by having a wrong calibration of the VCA DC balance VR 205 i been able to recreate your kind of problem..noise and high pitch on top of preset sound ...you may try this
http://i1211.photobucket.com/albums/cc433/z3sound/Sh2000.jpg


--- In vintagesynthrepair@yahoogroups.com, Scott Nordlund <gsn10@...> wrote:

>
> 
> >I'm having problems with an SH 2000 , it has this hi pitch squeal whenever I play a note.
> 
> >It's in pitch so it's not some random noise.
> 
> >It's still there when I turn of all presets ?
> 
> The sawtooth wave is made by mixing octave divided square waves. Maybe one of the higher octaves is coming through when it shouldn't.
>

Thanks , I tried the VCA DC Offset , it does help a bit .
For it to really help I need to turn it all the way up.
Its good to know that the hi pitch sound is there without any presets , that one was driving me nuts .

Not sure what to do next , the power supply seems clean?
I´m recapping it anyways .

Arnar




----- Original Message -----
Frá: "z3sound" <z3sound@...>
Til: vintagesynthrepair@yahoogroups.com
Sent: Miðvikudagur, 30. Nóvember, 2011 19:23:03
Efni: [vintagesynthrepair] Re: Hi pitched squeal in Sh 2000








tonight i have taken out my own Sh 2000 to take some measurement to try to help you find your noise problem ...but surprise with all preset off i got the same noise and in high pitch tone (in pitch with the keyboard),it is like the top oscillator VCO bleeding though the the supply. but when i hit a preset tab everything sound ok without any noise , and i thing it is perfectly normal to hear the noise when no preset is activated . i have try to undo some of the adjustment on the VCF/VCA board, and by having a wrong calibration of the VCA DC balance VR 205 i been able to recreate your kind of problem..noise and high pitch on top of preset sound ...you may try this 
http://i1211.photobucket.com/albums/cc433/z3sound/Sh2000.jpg 

--- In vintagesynthrepair@yahoogroups.com , Scott Nordlund <gsn10@...> wrote: 

> 
> 
> >I'm having problems with an SH 2000 , it has this hi pitch squeal whenever I play a note. 
> 
> >It's in pitch so it's not some random noise. 
> 
> >It's still there when I turn of all presets ? 
> 
> The sawtooth wave is made by mixing octave divided square waves. Maybe one of the higher octaves is coming through when it shouldn't. 
>