Dimensions ( W x H x D ) 15 cm x 19 cm x 10 cm / 6" x 7_1/2" x 4" Portable DC/AC V/A-Meter POST / SIEMENS & HALSKE Germany (1930) ******************************************************************** Class 0.5 3 V .. 300 V DC/AC 450 mV = 450 μA x 1 kΩ This beautiful instrument came "as-is" without its shunts. Now, because the ONLY AMPERE-RANGE is 450 μA, a SHUNT was home-made: Experiments with HELIPOTS & WHEATSTONE BRIDGE resulted in a 3 Ω RESISTOR to have a 150 mA (DC/AC) RANGE available ... R E M A R K S T O R E S T O R A T I O N : ==================================================================== AC was not working, because the "KUPFEROXYDUL-MESSGLEICHRICHTER" G1441/1 (= Bridge-Rectifier ) was defect. ... Disassembling ... Back Side Front Side A | ... showed: Dead rectifier pearls ! EXPERIMENTS with different Diode types ( Germanium-, Selen-, Silizium-, Tunnel-, ... ) until found the SOLUTION: 4 * BAT-43 SCHOTTKY BARRIER DIODES to replace the dead pearls - MATCHING THE EXISTING S C A L E CALIBRATION ! The G1441/1 DIAGRAM and a snapshot of the REPAIR PROCEDURE ... impressum: ******************************************************************** © C.HAMANN http://public.BHT-Berlin.de/hamann 04/27/09 |