Vintage Synth Repair

Sure, here a direct link to the manual (to big to upload):

http://www.hylander.us/images/schematics/sequential/Profit5v3TechManua
l.pdf

The PS was connected to the main board when the small heatsinks were 
used. The synth is made of two boards (the programmer board and the 
voice boards) which are connected on to each other.

The voiceboard only gets +15v and -15v from the main (programmer) 
board, while the main board has only one input from the power supply.

The PS is only connect to that port on the main board, so no other 
connection to -15v supply in the synth.

When I only connect the voice board to the -15v and +15v supplies, 
the voltages are CORRECT and no shorts... Does this indicate a 
problem on the main board ?




--- In vintagesynthrepair@yahoogroups.com, scott frye 
<painintheamp@...> wrote:
>
> Unless the circuit was connected to a load , I dont think that 
would cause any failures.
> 
> Does someone have a schematic that I can see?
> 
> gil_we <gil_we@...> wrote:                               Thanks,
>  
>  there's no short read between ground and -15 rail on the board, 
when 
>  cap is removed. The PS supplies -15v when unconnected. The rating 
of
>  the tantalum is 25v and it is placed correctly.
>  
>  One thing that I must note - when first connecting the PS, I used
>  smaller heatsinks than required for the regulator. Could the -15v
>  regulator go bad even though it still supplies -15v when the PS in 
not
>  connect to the board ? 
>  
>  --- In vintagesynthrepair@yahoogroups.com, scott frye
>  <painintheamp@> wrote:
>  >
>  > Tantalums are not at all forgiving in a reverse bias OR over-
voltage
>  setting.
>  > Remove the cap and see if you actually have a short circuit 
first.
>  Then make sure the voltage ISNT more than the cap rating. Otherwise
>  it's POOF again.
>  > 
>  > gil_we <gil_we@> wrote:                               Hi all,
>  >  
>  >  I'm trying to solve a problem with a P5 I just got.
>  >  
>  >  It looks like the -15v rail on the main board is shorting.
>  >  Each time I'll power it up, the 10uf tantalum capacitor which 
filters
>  >  the -15v is getting fried and open (shorting) immediately.
>  >  
>  >  Any ideas where to start looking at ? Any common parts on the 
P5 with
>  >  are known to short over time ?
>  >  
>  >  Thanks for the help !
>  >  
>  >  
>  >      
>  >                                
>  > 
>  > 
>  >   Scott  Frye
>  > AudioFixation
>  > Consumer / Pro Audio Repair
>  > Southern VT 
>  > 
>  >   
>  > 
>  > 
>  > 
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>                                
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> 
>   Scott  Frye
> AudioFixation
> Consumer / Pro Audio Repair
> Southern VT 
> 
>   
> 
> 
> 
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