[sdiy] ENSONIQ keyboard woes

[Nathan M. Reeves]

so i should clean the leads on the IC socket or on the ones that the  
keyboard ribbon cable connects to?
or both?
cheers
nate


On Jan 21, 2009, at 9:34 PM, Bob Weigel wrote:

> Just glancing...sometimes leads have persistent oxides on them  
> Nathan.   I seldom see dioes actually go totally open but it can  
> happen I guess.   Just.. be sure to scrape down leads before you  
> assume that it's really open so you are getting good contact.
>
> And some meters have built in buzzers to indicate continuity he  
> probably meant. -Bob
>
> Nathan M. Reeves wrote:
>
>> yes it seems like a long shot for the diode check.....
>>
>> i remember the korg polysix thing vaguely....
>>
>> fortunately my DMM has a diode/continuity check built into it
>>
>> its says to:
>>
>> 1. Remove all power from the circuit under test and discharge all  
>> caps.
>> 2. Set to proper selection on switch, looks like a little diode icon.
>> 3. Connect test leads to device you want to check.
>> 4. Reverse test leads and note second reading.
>>
>> If one reading shows a value and the other is over-range (0.F  
>> appears)  the device is good.  If 0.F appears during both readings,  
>> the device  is open. If both values are very small or zero, the  
>> device is shorted.
>>
>> I did this and got 0.F for both readings.... though I am not sure  
>> if  the diode I was testing had the key pressed (maybe i will tape  
>> all  keys down while i do this...)
>>
>> Tom Wiltshire says
>>
>> "You can buzz them through with a multimeter continuity checker,   
>> assuming it uses enough voltage to overcome the diode drop.  
>> Sometimes  they don't. This is why
>>
>> they also include a "diode test" setting on the multimeter. Still,   
>> I've found it easier with an audible clue.
>>
>> I tested a Polysix keyboard by taking it out of the instrument and   
>> lying it down upside down. This meant I could get to the PCB and   
>> connector, but more importantly
>>
>> meant all the keys were pressed down so I could test the diodes.  
>> To  avoid the multimeter problem I just mentioned, I tested it with  
>> a 9V  battery and a buzzer."
>>
>> what type of buzzer, just one from a PC will do?  i have PLENTY of   
>> those lol
>>
>> so it looks like if its not the diodes, keyboard contacts, nor the   
>> ribbon connector than its most likely the MCU
>>
>> i rather not pull the other MCU i have out of the working one.....
>>
>> Are these obscure and rare  (read expensive) to find?
>>
>> 8^(
>>
>> how do you check the ribbon cable for continuity?
>>
>> What ended up being the problem with your Polysix Tom?  Did you   
>> resolve it?
>>
>> How do I read through the archives again? 08^)
>>
>> Cheers,
>>
>> Nate
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