TrekII's percussion problem: electric noise sound

[dario882001]

Hi everybody,
I have got a C2 with TP-2B percussion by Trek ii. I noticed that, even if I set all the drawbars to zero level and same for percussion's sliders, I still get a "POP" sound similar to the percussion sound (but with no harmonics in it). This electric noise can be controlled in decay with the decay slider and it overlaps with the real percussion sound when percussion is selected.

Just to give more info and a schematic recap:
- it's a percussive electric sound, just like the real percussion
- this sound shows up only in the upper manual, when the dedicated percussion preset is selected
- it still shows up when no drawbars are selected and no percussion is selected on the sliders
- the noise is always there (underneath the percussion sound)
- this noise follows the decay control
- the organ is a US-made C2 running on 240V here in Italy, with a transformer

I checked the wires (especially the ground) and they look ok to me.
Not sure if it's normal or not (I guess not, but I'm not a technician).

Hope somebody can help me!
Thanks a lot :)

Dario

[Drawbar Dave]

Why don't you just ask Mike S at Trek II?

[dario882001]

I don't know Mike personally, but writing an email to TrekII was my plan B. First I'd like to know if that noise is the normal behaviour or something wrong...

[tmccann]

If plan B proves necessary, don't hesitate to send an email to [email protected]. Michael will definitely respond and help you sort it out. He's helped me chase several gremlins out of my Hammond and Leslie stuff.

[dario882001]

You are absolutely right. Just sent an email and got reply.

[geoelectro]

There is a "null" adjustment, R25. It's purpose is to minimize any sound during the percussion envelope. It may need tweaking.

Geo

[dario882001]

That's great. By tweaking the trimmer I reduced the noise to a negligible level (in comparison to the previous one). Let's see if Michael from Trekii company can give me some more advices, otherwise I will consider the problem solved. I'll post the end of the story anyway as future reference.

[dario882001]

Noise reduced to negligible level by tweaking the trim pot on the unit's board. Problem solved. Thanks to all