Supply 139B speaker polarity tester

? Subject to environmental noise, and immediately determined that any type of speakers, the polarity of the headset for use in the production line. ? Can be used with three different instruments on-line (152A, 7117C, and 7116C), only one person can operate, labor saving. ? Easy to learn, easy to use, excellent reliability. A positive polarity pulse measurement mode polarity: green LED lights and beep b negative: red LED lights buzzer will not sound sensor condenser microphone ECM five group select switch WF: suitable woofer M & T: Suitable tweeter & headphone Ext.1 ~ Ext.3: External Instrumentation Interfaces