JBL 6021 Assembly, Installation And Service Manual

InstallationThe 6021/6022 is suitable either for rack mounting infour EIA rack spaces without additional bracing orventilation, or for counter-top placement. A full set ofmounting hardware is packed with each unit. All exter-nal connections and matching/bridging transformeroption are made on the rear panel, Figure 1.Operating TemperatureBecause the 6021/6022 is cooled by convection,adequate clearance on the top of the unit must beprovided to allow heat dissipation. The m i n i m u mr e c o m m e n d e d clearance when stacking the unit isone EIA standard panel space.A thermal switch in these units provides thermalprotection by shutting d o w n the amplifier if the internaltemperature exceeds a safe operating level. The max-i m u m allowable ambient temperature for the amplifieris 6 0 ° C (140°F).Operating ControlsAll operating switches, meter and level control arelocated on either the front panel or the rear panel,Figure 1. Control, meter and switch functions are givenin Table 1.Input ConnectionsInput connections to the amplifier may be either direct-coupled or transformer-isolated at the LINE terminalstrip, TB301, or the RCA-type phono jacks, J 3 0 1 ,Figure 1. Direct coupling is accomplished by c o n -necting the center conductor of a shielded cable toLO and the shield lead to G N D , or to either RCA-typephono jack, Table 2 lists the terminals and the RCA-type phono jacks and applications of the LINE terminalstrip. For transformer-isolated input, (Figure 2) mustbe plugged into the 9-pin receptacle, XK301, Figure 1.The input leads are connected to terminals HI, LO andG N D of the LINE terminal strip.Output ConnectionsTable 3 shows the output configurations available.T A B L E 1G a i n Controls input of amplifier. C o n t r o l is wiredahead of the active circuitry and can be used asan input pad to prevent overloading and clippingof the non-inverting operational amplifier stage.NOTE: W h e n the J B L 5195 m a t c h i n g / b r i d g i n gtransformer is used, the gain control is acrossthe output of the t r a n s f o r m e r and therefore c a n -not be used to prevent input transformer satur-ation if excess input levels occur.Power S w i t c h Applies primary power to amplifier.M e t e r Provides a p p r o x i m a t i o n of the output level,with + 3 indicating that the amplifier is deliver-ing its rated c o n t i n u o u s sine wave power into4 a .L o w c u t / o u t Offers the user a response roll-off of 6 dB peroctave below 2 5 0 Hz.FIGURE 2T A B L E 2 / T A B L E 3Terminals(TB301)Terminals(TB302) Impedance Direct Out Transformer Out LinkLO, Chassis G N D 4 O (28.3 V) Yes N o n e8 O c o m 8 0 ( 4 0 V) Yes " H I " t o " X F M R Primary"16 O c o m 16 0 ( 5 6 . 5 7 V) Yes " H L t o " X F M R Primary"70.7 V c o m 25 O Yes " H I " t o " X F M R Primary"TerminalsRCA-TypePhono Jacks Function Application Terminating Resistor Special Instructions50 kOG N DDirect C o u p l e d For unbalanced high i m p e d a n c e(50 kO) sources— none—" A " o r " B " - n o n e —HILOG N DTransformer isolated Balanced high i m p e d a n c e(15 kO) source up to level of+ 15 d B m (with 5195 m a t c h i n g /bridging transformer)— none —Balanced 6 0 0 O source up tolevel of +15 d B m (with 5195transformer)6 2 0 O, y2 W, c o n n e c t e dto terminals " H I " and " L O "Balanced 6 0 0 Cl s o u r c e withup to level of 4 d B m with14 d B additional gain.- n o n e - Internal modificationrequiring servicetechnician.