Vintage Synth Repair

Hi there,

I'm still trying to get this Jupiter 6 going here... it locks up on boot with the lfo 2 light flashing.  I found the problem is somewhere on the 4 voice board... I can measure 5volts on the dac offset which is wrong... but I can unlock the 4v board (and play the 2 voice board)by grounding test point 1 & 0 bringing it where it should be...0v.  I've been trying to sort this out for awhile now...  I think I've realized one reason I can't seem to get anywhere is somehow the circuit board revision I have is not in any of the service manuals on the net. 

 All of the manuals I find are the "Larry Hendry" version and do not help.  My boards don't use the ITS80141 DAC but have a circuit board with some motorola dac and some other 40HXX series chips soldered into a socket directly into the spot the 80141 is.  Some of the resistors are different too, like in a totally different spot.

Does anyone know the circuit board I'm talking about and have the missing pages from the service manual available?

You might want to try asking the europa guys..

--- In vintagesynthrepair@yahoogroups.com, "adhmzaiusz" <adhmzaiusz@...> wrote:

>
> Hi there,
> 
> I'm still trying to get this Jupiter 6 going here... it locks up on boot with the lfo 2 light flashing.  I found the problem is somewhere on the 4 voice board... I can measure 5volts on the dac offset which is wrong... but I can unlock the 4v board (and play the 2 voice board)by grounding test point 1 & 0 bringing it where it should be...0v.  I've been trying to sort this out for awhile now...  I think I've realized one reason I can't seem to get anywhere is somehow the circuit board revision I have is not in any of the service manuals on the net. 
> 
>  All of the manuals I find are the "Larry Hendry" version and do not help.  My boards don't use the ITS80141 DAC but have a circuit board with some motorola dac and some other 40HXX series chips soldered into a socket directly into the spot the 80141 is.  Some of the resistors are different too, like in a totally different spot.
> 
> Does anyone know the circuit board I'm talking about and have the missing pages from the service manual available?
>