Vintage Synth Repair

One note leaking is not on the voice board.  It is on the keyer board for that note(each keyer handles 3 pitches for the right hand.  Most likely a 1N4144 signal diode. If you wet your finger and place it over the suspected signal diode the leak or cypher will increase.  Or use the diode test function on your meter, which should read the same as the other 100 plus diodes at .7xx volts drop.  

Also make sure the two zener diodes  on  each keyer board are correct with 14 volts and 7.5 volts too.  Re-seat the LSI.  These were the most common failures.  And the molex edge connector issues that plagued this era of Hammonds.  





>________________________________
> From: Nicolas <nico678@yahoo.com>
>To: vintagesynthrepair@yahoogroups.com 
>Sent: Monday, September 9, 2013 7:01 AM
>Subject: [vintagesynthrepair] Re: Hammond piper
> 
>
>
>  
>Hi,
>
>I think I had a similar problem one the piper that I repaired a few years ago. 
>I think I replaced Q6, Q7 and C37 on the voicing board and D9 and C1 on the power supply board.
>
>Ii's always a good idea to recap the power supply in those old organs.
>
>Nicolas
>
>--- In vintagesynthrepair@yahoogroups.com, "Nicolas" <nico678@...> wrote:
>>
>> 
>> 
>> Hi,
>> 
>>  I scanned a few files that I thought might be useful to solve this problem. I uploaded them in the files section of this forum. I think the problem might be coming from the voicing board but I might be wrong. 
>> 
>> Like I said, this is a pretty big service manual so you might check in the table of contents and the list of illustrations to see if you need some other files in order to solve the problem. I will scan them and upload them.
>> 
>> Nicolas
>>
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