Weston model 341 voltmeter 0-150-300-600 Volts full scale deflection AC/DC electrodynamometer type instrument. The meter is brought into circuit via a push button [lower left]. The meter is now working after the removal and replacement of faulty internal resistors by a selection of good ones removed from this similar instrument. Final adjustment of the resistor values was accomplished by shorting out sections as required. As a result of poor storage mould had grown on the varnish used to keep the fine resistance wires in place and caused them to go open circuit. The original calibration table and instruction card in the lid indicates that the instrument could be relied upon to within 0.25 percent of FSD. Date of calibration 29 January 1936. Weston Electrical Instrument Company, Newark New Jersey USA.
This is one of many instruments collected by Jack Davidson C Eng FIEE which I have been given by Dr Graham Winbolt
Three of the faulty resistors removed from a similar instrument.
Edward Weston [1850-1936] founded the Weston Electrical Instrument Company and held 334 patents.