HP-Service-Note-412AR-2 电路图.pdf

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1、41 2AR-2 ($3 MODEL 412AR DC VACUUM TUBE VOLTMETER (Rack mounted Instrument) SERIAL 134-05282 AND BELOW i IMPROVED GROUND CONNECTION To facilitate using the Model 412AR* DC Vacuum Tube Voltmeter, Serial 134-05282 and below, with a “floating” ground, the easy-to-make circuit change described in this S

2、ervice Note is necessary. Installation of this modification will provide a better ground connection for the shielded cable leading from the Modulator Assembly to Amplifier Tube VlOLA. This new ground will eliminate bias circuit disturb- ances when use of your Voltmeter requires an input isolated fro

3、m ground. * Rack mounted instrument only. 1 i MODIFICATION PROCEDURE 1) Disconnect power and remove cabinet. 2) The black lead extending from the modulator end of the shielded cable (routed from the Modulator Assembly to Amplifier Tube VlOlA) should be dis- connected from the center terminal of the

4、five-pin terminal strip, This terminal strip is located near the rear panel OUTPUT terminals. 3) Connect this black wire to the main ground terminal on the Modulator Assembly, (At junction of two other black leads.) 4) Replace cabinet. 5) No adjustments are required - an operating check completes the modification. i distribution abcfg4 I I L# 01222- 1 RadioFans.CN 收音机爱 好者资料库