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Static noise problem with my TR-909 Drum Machines & Samplers
Old 14th January 2018
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Static noise problem with my TR-909

I have a problem with background static crackling and popping on the hi-hat and ride of my 909. The sounds play fine..but the background noise is really loud rendering them unusable. The noise is there all the time without triggering the sounds. You have to turn the separate volumes down to shut it off. The noise is on the separate and main outs..the rest of the sounds are perfect with zero noise.

What I find weird is according to the service manual the ride and hihat share no common components or circuit..yet the fault happened at the same time.

Any ideas?

Last edited by Space Station; 14th January 2018 at 02:08 PM..
Old 14th January 2018
I bet @atsushi_hoshiai will know what it is. PM him if he doesn’t see this.
Old 14th January 2018
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Ok thanks.. crackle is insane today!
Old 15th January 2018
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I didn't hear from him, but anyway I fixed it.

One bad 2sc2603 transistor in the Ride circuit and one bad 2sc2603 in the Hi-hat circuit.

I replaced them with the much more common 2N3904 transistor. (NOTE 3904 pinout is EBC and 2603 pinout is ECB, so you have to bend the leads)

What confused me is that both went bad at the same time, which is really strange. It led me on the path that it must be a shared component...but no components are shared by those circuits..

So for the archive....there you go..hope it helps someone else someday.

Last edited by Space Station; 15th January 2018 at 04:14 PM..
Old 15th January 2018
I am going to subscribe to this thread just in case I ever need it.
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