The Model 955 is a truly advanced, highly dependable in-circuit and out-of-circuit capacitor tester. In addition to providing extraordinarily sensitive short and open tests, the Model 955 includes a Wien Bridge for capacity measurements, with a unique shunt resistance balancing provision* that permits in-circuit measurement even when the shunting resistance is comparatively low. 1-2. FACILITIES Indicator: Electron-ray tube EM84/6FG6 Bright bar pattern gives sharp, unmistakable indications. Test Selector: Three-position switch — SHORT, CAP- ACITY, OPEN Test Leads: One coax-type for all tests; detachable, with input connector coupling to unit. Short Test: Out-of-circuit or in-circuit short check with shunt resistance as low as 1 ohm. Reliable up to 2000mf. Closed bars indicate short. 60 cps test frequency. Max. test voltage 6.3VAC (open leads), decreasing with decreasing impedance. Open Test: Out-of-circuit or in-circuit open test of capacitors as small as 15mmf with instrument adjusted normally. {With constant voltage supply, internal adjustment can be made for 5mmf sensitivity). For in-circuit testing, shunt resistance may be as low as 35 ohms for capacitors above lOOmmf (3ΚΩ at lOmmf). Closed bars indicate open. Test frequency approximately 22Mc, very low voltage. Capacity Measurement: From 0. 1 to 50mf using Wien Bridge with unique shunt resistance balancing* permitting ± 10% accuracy at any point on the capacity dial in either in-circuit or out-of-circuit measurement. The capacity scale is screened on a 4" diameter, heavy- gauge lucite disc. The reading point is just above the center of the indicator bar-pattern. Operating frequency of the bridge is 60 cps. The RC BALANCE control is calibrated in RC product (equivalent shunt resistance in kilohms multiplied by the capacitance in microfarads) in two ranges, 0.6 to 10.5 and 1 to infinity, selected by the RC RANGE switch. The very wide RC product range provided, with excellent spread permitting easy setting to any value, is the key to the accurate capacity measurement provided either in or out of circuit. For out-of-circuit measurements, the RC product value can be translated into dissipation or power factor with the help of the graph on page 16. Line Voltage: 105 to 130VAC, 60 cps; 8 watts drain. A LINE ADJ control on the panel permits adjustment to maximum sensitivity regardless of the voltage variation within this range. Miscellaneous: Exceptionally attractive, professional laboratory styling. Transformer-operated and protected by fuse in extractor-post mount. Tubes: 1-6C4, 1-EM84/6FG6. Size (HWD): 8 1/2” x 5 3/4” x 6” Weight: 4 lbs.