Qsc - Plc0004 电路图.pdf

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1、1PLX0004 Title:PLX Gain Modification Bulletin #:PLC0004Issue Date:July 13, 2000 Models Affected:All PLXBulletin Revision:A Production Range: All Service Bulletin Description Some PLX users need an amplifier gain structure that is different from the amplifiers standard 40, or 32 dB. This is an electi

2、ve customization procedure, not a remedial one. This bulletin describes the procedure for modifying the amplifier circuitry to obtain certain other common gain values. Instructions Replacing the input resistors in the amplifiers differential input circuitry with ones of a different value will result

3、 in a different gain value. Tools and materials required: Soldering iron with fine tip (recommended range 25 to 60 W) Rosin-core solder (60/40 or 63/37 eutectic type) Long-nose pliers #1 and #2 Philips screwdrivers Small diagonal cutters Desoldering equipment or solder braid Precision resistors (1%

4、tolerance or better recommended); 2 required per amp channel; see table at right for values Replace these resistors to alter Channel 2s gain Replace these resistors to alter Channel 1s gain Bdn i , n i agde r i seDn i agder i seDecna t s i seR Bd0201k1 . 22 Bd225 . 21k8 . 71 Bd321 . 41k8 . 51 Bd6202

5、k3 . 11 Bd8252k78 . 8 Bd0323k89 . 6 Bd2304k26 . 5* *Standard gain for PLX Series amplifiers. Procedure: replacing resistors Prepare (bend and trim) the leads of the new resistors before installing them. 1.Disconnect the amplifier from AC and wait at least 10 minutes for internal voltages to bleed do

6、wn. 2.Turn the amplifier over and remove the screws from the bottom cover of the chassis, then remove the cover. 3.To change the gain of Channel 1, locate resistors R8 and R9 (Figure 1). Replace them with matching resistors that will provide the desired voltage gain (see table above right). 4.To cha

7、nge the gain of Channel 2, locate resistors R129 and R130 (Figure 1). Replace them with matching resistors that will provide the desired voltage gain (see table above right). 5.Replace the bottom cover and check the amplifier to make sure it works correctly. Figure 1. Locating resistors R8, R9, R129

8、, and R130 RadioFans.CN 收音机爱 好者资料库 2PLX0004 Contact information If you need any further information regarding this service procedure, please contact QSC Technical Services at the addresses or numbers below. Telephone: 800-772-2834 (within USA only) 714-957-7150 Fax: 714-754-6173 E-mail: tech_ Postal and parcel address: QSC Audio Products, Inc. Technical Services Group 1665 MacArthur Blvd. Costa Mesa, CA 92626 RadioFans.CN 收音机爱 好者资料库