RD-88 Mic input problems

[Jakdne]

I've tried connecting an SM58 to the mic input on my RD-88 using a female XLR to male TRS cable. This has caused the mic to continuously dispense small electric shocks. This has happened with two different RD-88s now, my original and a replacement. It has been tested with multiple different mics and cables, both at my house and at my university to make sure it's not a problem with my own power system.

After discussing it with a customer service guy from the store I bought the RD-88s from, he said that he's been informed that RD-88s aren't grounded, you're supposed to use a mixing desk or something with its own grounding as a middleman, rather than plugging a microphone in directly. As the RD-88 manual simply tells you to plug the microphone into the keyboard and doesn't mention anything about needing a mixing desk or warn about potential shocks at all, I'm confused, and I have to admit I'm not completely certain I'm being told the truth. At the same time, though, I can't think of any other reason why two different keyboards from such a prestigious manufacturer would have such a fault.

Is XLR to TRS the wrong type of cable? The manual didn't specify the type, and it's possible I should be using XLR to TS instead, but surely using TRS instead would simply cause sound issues at worst, not electric shocks? I'm not an expert though.

Overall, very confused and frustrated by this experience, and would appreciate help from anyone who might know what's going on.

[peternh]

I use an SM58, and Sennheiser dynamic mics, with no problems into my RD-88 mic input, using XLR to TS (mono jack) connector cable. Have never tried TRS, but I don't think it's wanting a balanced connection.

[Jakdne]

I just bought an unbalanced XLR to TS cable and tried it out, and I had the same problem again.

Do you plug your RD-88 into anything else? Like a mixing desk or monitors?

[peternh]

I just bought an unbalanced XLR to TS cable and tried it out, and I had the same problem again.

Do you plug your RD-88 into anything else? Like a mixing desk or monitors?

Yes, I plug into active monitor speaker (Yamaha or Acoustic Image) from line out.

To be clear, I use - "VisioSound Female XLR to 6.35mm 1/4" Mono Jack Lead/Microphone/Signal Cable 1m" - into rd88 mic input, and then the other (xlr female) end into the lead from a mic - works with sm58 or many other dynamic mics (on jam sessions). Hope that helps.

[Jakdne]

Ah, I see. The support guy told me that plugging something grounded like monitors would prevent the electric shocks, so that's probably the difference. Unfortunately I don't own any, so I'm not sure what to do.