[sdiy] Help trouble shooting mfos echo rockit

[Pete Hartman]

I just looked over the schematic, and I think you're right, it's likely to
be one or the other of the MPF102's.

Some other N Channel JFETs I have around that I would try to sub in (no
deep analysis of characteristics here though), J201, 2N5457 2N3819,
2N4392.  If all you have is what you got in your kit, you'll have to source
something from Mouser or Digikey or somewhere.  Might talk to the kit
provider as well, I know some of them will provide replacements.





On Sat, Nov 19, 2022 at 11:18 PM JoeF <frey at radioles.com> wrote:

> Hello all, not sure if this is the right place to ask for guidance but,
> I'll try. I have put together an Echo Rockit I got as a kit. And, of course
> I need to troubleshoot.
> This is an oscillator and external input into a VCF into a PT2399 delay. I
> am getting no sound at the output and I believe it is because the VCF is
> not functioning. I have audio traced a signal to the VCF from the input and
> the internal oscillator. And, I have jumped the signals around the VCF
> straight to the delay and then I get output and have verified the delay is
> operating as expected. I have correct power to all IC power pins. The
> transistors are getting power on their source pins.The IC in the VCF is an
> 13600D which I have spares of and have swapped to no avail. I have
> re-soldered the components in the VCF circuit. I don't have extras of the
> MPF102 transistors and am questioning whether I burned them up when I
> soldered them in? What do you think?
> What's next? Thanks for any advice in advance. JoeF.
>
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