Can you use a6 volt600 ma adaptor on a 6 volt 200 ma?

Yes, you can use a 6-volt 600 mA adaptor with a device that requires 6 volts and 200 mA. The adaptor's higher current rating (600 mA) means it can supply more current than the device needs, which is safe as long as the voltage matches. The device will only draw the current it requires (200 mA). Just ensure that the adaptor's voltage is stable and does not exceed 6 volts.