Vintage Synth Repair

That should be (connector C6), not (connector C60. Hadn't had my coffee yet.

--- In vintagesynthrepair@yahoogroups.com, "65 Lotus" <Lotus@...> wrote:
>
> On the DM board, check the capacitors on the ±15 volt power rails (connector C60. See if they're tantalums and shorted.
> 
> There's two by the connector, but two others elsewhere on the board, so track them down. I'd replace with electrolytics in this case, simple power rails.
> 
> Also, there's a couple on the 5 volt rail too (connector C12), might as well replace those while you're in there.
> 
> Scott in Ohio
> 
> ----- Original Message ----- 
>   From: Daniel Forró 
>   To: vintagesynthrepair@yahoogroups.com 
>   Sent: Monday, April 08, 2013 11:47 PM
>   Subject: Re: [vintagesynthrepair] Yamaha CS40m problem
> 
> 
>     
>   Recently I tried to switch on my two CS40m synths which I have used 
>   for the last time about 7 years ago. Main fuse on both machines was 
>   blown after one second.
> 
>   So I have recapped both PSU, and tried to switch on again. On one 
>   machine big two resistors connected in series to output rails +15 and 
>   -15 V became so hot that their textile envelope (yes, they were 
>   covered by some textile pipe) started to smoke. (On the other machine 
>   not so bad, but again main fuse and another one in the secondary 
>   circuit was blown.) I have immediately switch off, put both PSU out of 
>   the instrument, switched on without a load, and both PSU are OK, 
>   everything works. So I could set all four voltages to their spec 
>   levels (+15, -15, +5, -10).
> 
>   Am I right to suppose there's a short circuit on some board? I wonder 
>   how it could happen when the instrument was not at all used for years. 
>   In one instrument there was small leakage of RAM battery (as they use 
>   standard 2 AA size batteries in battery compartment, no damage was 
>   caused by this). Otherwise everything looks well.
> 
>   Has somebody any advice how I should continue and where to find the 
>   source of this problem? Could it be some shorted tantalum capacitor? I 
>   can't use PSU and switch on the instrument. I plan to recap, clean and 
>   check all boards, clean connectors... usual stuff. Then try again to 
>   switch on... If it will work without blowing the fuses or burning 
>   components, then I can check voltages and signals. I have Service 
>   manual.
> 
>   Thanks in advance for any hint.
> 
>   Daniel Forro
>