bass ++ troubleshooting help needed

[cheese_nucleus]

hi forum!

this is my first post here. for a long time i was only reading. this place is really
a great inspiration for me!

so, hello everyone!


after successfully building the MFOS 16step sequencer i wanted to build the bass ++.
sadly i wasn't successful yet. i'm having trouble getting the LM13700 to work, i think. i makes sounds, but the only thing, that i can hear is the impact sound, that comes out of the TL072. so far, the pots for trigger sens, impact tone, impact volume and master volume work. the other pots, that are LM13700 related have no effect at all. i've quadra checked everything, but i can't see the mistake. the only thing, that hapens with the LM is, that it's getting slightly warm, when the power is turned on. the whole circuit is connected to +-9V. as jean-louise said in another thread, the 9V power supply works perfect for him, so this might not be the problem.

i've attached a drawing of my stripboard layout. the pots are not shown in this drawing and the resistors that are connected to the pots are not on the stripboard, but directly on the pins of the pots.

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[State Machine]

If everything looks good to you, it may be a bad LM13700 if it's getting warm. Because it is really easy to damage an OTA, just make sure you check once again (penta checked) that your not overstressing the part before you replace it.

Bill

[cheese_nucleus]

hey! thank you for your advice. i didn't know, that the LM chip can break easily...
at the moment i'm pretty busy, so i've no time to work on the ++. as soon as i'm
back on the project i will check the circuit once again, or maybe i will breadboard
the part of the circuit with the 13700.

cheese nucleus

[State Machine]

OK, whenever your ready. And, BTW, not sure if your aware but there is a Quad version that will be in production soon. You can built up to four on a single circuit card.

http://electro-music.com/forum/topic-39402.html

Bill

[cheese_nucleus]

yeah, i've seen the quad version. so, if i can't get the ++ to work on a stripboard, i will have to get a PCB anyways!

[State Machine]

[cheese_nucleus]

hey, thanks a lot for offering me the LMs! but over here in berlin i've good suplly on those
chips, so i can fry as many as i want (or as long as i've got the cash)...

thanks again!

cheese nucleus

[State Machine]