Mark 1 LTD Question

[Passing Thru]

Just purchased this detector knowing it has a problem...All knobs set at preset (Blue) and battery check showing full charge...When I toggle left or right there is an erratic, chirping and a low to high pitch sound...Once in a while it will perform like it should with needle pegging on correct coinage...This detector came with two red 7 inch coils and a white 10 inch coil...All coils perform as stated above...

 

[rbholt80]

could be the switch. iv used the mark1 and still have one. that detector is old and probably needs the electrolytic capacitors replaced. they only have a lifespan at best 20 years.
another good idea is to have the solder re-flowed or touched up by hand. iv found many issues with electronics cause by bad solder joints that have cracked with age for thermal expansion and contraction over the years. all those are very cheap fixes if done by you. truely not difficult just do a little research on soldering and replacing capacitors. bet you could fix it for $30 and get 30 mores years out of that detector.