Cgs synth

>The buttons are still no go, checked the B line, and it WAS way below 7.5v

due to the fact that i was trying to run it at 12v.

>I reconfigured my power supply to run at 15v and B line now runs at 7.55v

but still no dice with the buttons.

>diodes all oriented correctly, no problems there.

>Interesting observation here when i push the button, the B rail drops to

6.7v. not sure if that is expected behavior or not.

Pushing the button adds a load, so I would expect a voltage drop. It SHOULD
run from 12 volts with the B line at 6V too.

Check the CPO circuit. That is the only other thing that is common to all
the push buttons. Make sure the capacitor there really is 10n and not 100n
or something like that. Maybe even try it without that capacitor.

Ken

>--- In cgs_synth@yahoogroups.com, "cg_synth" <sasami@...> wrote:
>>
>> First, check your "B" line is at 7.5 volts. If it isn't, that is why your

buttons don't work. The B line puts the voltage on one side of the switches.
Also check each push button connects to the cathode of its two diodes.

>>
>> As for the step 3 failure, the problem will be one board 3 (Check around

the PNP transistor pair, and connections F and J) or board 2 (trace from "H"
to make sure it actually connects to the rest of the circuit on board 2 - no
broken traces or whatever).

>> Ken
>>
>> --- In cgs_synth@yahoogroups.com, "ch1nard" <steve.benesko@> wrote:
>> >
>> > I've been building a SWAMP pannel and i've pretty much got most of the

CGS59 functions working with a couple of exceptions that i just cant seem to
figure out.

>> >
>> > First is pretty easy to explain, pushbuttons dont seem to work.
>> > I've gone over all the buss connections plus double checked all the

diode orientation.

>> > The pulse inputs are all working fine, so i have a feeling i am missing

something really obvious and stupid.

>> >
>> > The other problem is a bit of a weird one, but i'm sure is easy to solve.
>> > So applying pulse UP works great. Able to step through all 8 stages

and wrap around again.

>> > Applying pulse DOWN stops on stage 3 and will go no further.
>> > I've gone through and triple checked all the buss connections as well

as the G/H/J wiring. It does work in one direction so i am thinking the
problem might be somewhere in or near the pulse generators on the A boards.

>> >
>> > oh btw.. these are the earlier revision boards (non-rohs) the one

where you have to reverse the orientation of the BC547 on the A boards and
install that 1M+1N4148 in chain.

>> >
>>
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_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>