These detectors are getting on on in years but they all are very good detectors, all can be modded up and detect in most cases as good as the newest detectors that are so very expensive.
The most simple fix is replacing the 150uh inductor in the switching power supply. Over the years the capacitors dry out and lose their electrolyte, this lack of capacitance causes circuit instability
and thus a noisy detector. Replacing the 150 uh inductor in the power supply with a physically larger shielded type with less inductance of 100 uh does a number of things. First is raises the self resonant
switching frequency, this causes less noise as the internal power supply is more smooth in output. The higher the frequency the less ripple and those dried out caps can filter out the noise as the switching transitions
are less in amplitude. Also the detector starts faster, to me this because the existing inductor suffers ferromagnetic collapse at high start up inrush currents. The supply actually runs cooler.
