Vintage Synth Repair

I have an old +/-15v .5A power supply that is very noisy and I 
suspect it is in need of servicing; potentially a rebuild.  Does and 
body have experience doing this kind of thing?  I have schematics and 
a service manual and my scope should be here monday.

Any help will be greatly appreciated.

Thank in advance,

Ethan

Ethan, Feel free to call Jeff Blenkisopp at Expert Audio Repairs in NYC... 
212 868 4357... He is one of the best synth repair guys in the country. He 
also is an engineer on many products.. Tell him Chris from Vintage Vibe 
reffered you. Good luck!

HI,
in a lot of older power supply units its likely that the electrolytic
smoothing caps may need changing .
this applies to both the linear and the switched mode supply units .
modern electrolytics may be smaller that the older ones you are
replacing .you should always use caps with at least the voltage rating
of the ones you are replacing .I't not a good idea to increase the
capacitance value of the replacements as this can cause other parts to
fail [ such as the rectifier diodes ].
remember that a switched mode supply will need a load on it to work
corectly .
regards Peter 

ethanzer0 wrote:
> 
> I have an old +/-15v .5A power supply that is very noisy and I
> suspect it is in need of servicing; potentially a rebuild.  Does and
> body have experience doing this kind of thing?  I have schematics and
> a service manual and my scope should be here monday.
> 
> Any help will be greatly appreciated.
> 
> Thank in advance,
> 
> Ethan
> 
> 
> To unsubscribe from this group, send an email to:
> vintagesynthrepair-unsubscribe@egroups.com
> 
> 
> 
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

-- 
web page http://home.clara.net/dragonser/index.html

--- In vintagesynthrepair@y..., Peter M Blackett <dragonser@c...> 
wrote:
> HI,
> in a lot of older power supply units its likely that the 
electrolytic
> smoothing caps may need changing .
> this applies to both the linear and the switched mode supply units .
> modern electrolytics may be smaller that the older ones you are
> replacing .

Hello Peter,

Can this account for the hum coming from the supply?  I mean the 
supply itself actually hums and crackles.  I don't mean not hum and 
crackle in the audio path.  The supply actually sounds like 
electricity sound efx from 1930s/40s b-grade sci-fi and horror 
movies. 

Thanks again,

Ethan

Hi Ethan,

You will probably find that the 'noise' (if you mean actual sound rather
than instability of supply), is caused by the
transformer. Check the transformer mountings for security and tighten down
where required. This may help.

Regards,

Ron.

  -----Original Message-----
  From: ethanzer0 [mailto:ethanzer0@...]
  Sent: 27 June 2002 19:47
  To: vintagesynthrepair@yahoogroups.com
  Subject: [vintagesynthrepair] Repairing power supply.


  I have an old +/-15v .5A power supply that is very noisy and I
  suspect it is in need of servicing; potentially a rebuild.  Does and
  body have experience doing this kind of thing?  I have schematics and
  a service manual and my scope should be here monday.

  Any help will be greatly appreciated.

  Thank in advance,

  Ethan


  To unsubscribe from this group, send an email to:
  vintagesynthrepair-unsubscribe@egroups.com



  Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

Ron is right, mechanical noise from the power supply is usually 
caused by loose transformer mounting screws. Sometimes the 
laminations on the transformer itself loosen and get noisy. Assuming 
that it is a 2600 power supply---There are four screws on the 
transformer case that you should try tightening. I would also check 
the power supply board for bad solder connections too. 


Regards,
John Hannon
(ARP factory tech 1975-1981)




--- In vintagesynthrepair@y..., "Ron Lake" <electron@b...> wrote:
> Hi Ethan,
> 
> You will probably find that the 'noise' (if you mean actual sound 
rather
> than instability of supply), is caused by the
> transformer. Check the transformer mountings for security and 
tighten down
> where required. This may help.
> 
> Regards,
> 
> Ron.
>   -----Original Message-----
>   From: ethanzer0 [mailto:ethanzer0@y...]
>   Sent: 27 June 2002 19:47
>   To: vintagesynthrepair@y...
>   Subject: [vintagesynthrepair] Repairing power supply.
> 
> 
>   I have an old +/-15v .5A power supply that is very noisy and I
>   suspect it is in need of servicing; potentially a rebuild.  Does 
and
>   body have experience doing this kind of thing?  I have schematics 
and
>   a service manual and my scope should be here monday.
> 
>   Any help will be greatly appreciated.
> 
>   Thank in advance,
> 
>   Ethan
> 
> 
>   To unsubscribe from this group, send an email to:
>   vintagesynthrepair-unsubscribe@e...
> 
> 
> 
>   Your use of Yahoo! Groups is subject to the Yahoo! Terms of 
Service.