Line_6_Flextone_2_HD_Service_Manual电路图.pdf

Service Dept. 6033 De Soto Ave. Woodland Hills, CA 91367 P. 818-575-3600 F. 818-676-1585 E. *WARNING!* Dangerous and lethal potentials are present in this product! Before proceeding any further, the service center is warned that caution must be used when troubleshooting, repairing and testing the circuits in this unit. High voltage AC line-connected potentials are present in the circuits used in this unit. All work performed on this unit must be done with an isolation transformer connected between the power circuits input and the AC line in order to prevent electric shock, especially when connecting test equipment to the circuit. Extreme caution must be used when working on this product! RadioFans.CN 收音机爱 好者资料库 HDII Power Amplifier Theory of Operation Overview The HDII power amplifier is designed to “model” many of the characteristics of a tube amplifier. So it is significantly different from “typical” solid state amplifiers. The output stage consists of a class H, push-pull MOSFET transconductance power amplifier. A limited amount of negative feedback is used to reduce the output impedance. Both transconductance and the amount of negative feedback are switched to match the output impedance of the amplifier to the load. Output Stage The output stage consists of four power MOSFETs configured as voltage controlled current sources. For the MOSFETs connected to the negative rail, operational amplifiers are connected to drive the gates of the MOSFETs such that the voltage at the non-inverting input of the op-amp is equal to the voltage across a current sense resistor connected to the source of the FET. For the “high-side” MOSFETs a similar arrangement is used but in an inverting configuration. Local Power Supplies The op-amp that drives the high side power MOSFETs requires a 12V power supply is referenced to the output voltage. To create this “floating” supply Q20, Q34 and Q39 regulate +BIAS_HIGH while the output is below +LOW. During the part of the waveform that the output is above +LOW C25 holds-up +BIAS_HIGH. For the low side op-amps Q21, Q23, Q33 provide a similar function. Since the output voltage can go all the way to the negative rail, a negative supply is required for U7 to maintain control of the high side MOSFETs. This negative rail is provided by Q35 and D10. The power amplifier uses a new TLC084 op-amp. This op-amp has very low offset voltages, low noise and can run from a single supply, but its maximum supply voltage is 16V total. This is why Q18 and Q19 are used to derive a 6.8V supply from the 15V rails. The class H step switches Q2 and Q12 have similar gate drive requirements to the main power devices. In these circuits, the gate drive voltage is controlled by the level shifting circuits. Class H Step Switching To modulate the power rails going to the output stage, comparator U10 switches the appropriate circuit when the output voltage approaches either rail. A small amount of hysteresis is used to eliminate chattering around the switch point. Signal Processing Phase Splitter To drive the output stage, a voltage analog of the desired current needs to be developed. This is done with U4-A,B,D and associated circuitry. Mute Circuit RadioFans.CN 收音机爱 好者资料库 The amplifier is muted by pulling JFET Q31s gate to 15V. The main board provides a mute line that mutes the amplifier when it is low and un-mutes in the high (+5V) state. The main board will mute the amplifier at startup and when in STUDIO MODE. The amplifier also mutes it when the supply voltage is below the breakdown voltage of D21 about 18V. Output Impedance Switching Analog switch U1 provides the switching for the 4, 8 and 16 Ohm settings. This is done by simultaneously adjusting the transconductance and the open circuit voltage gain to match the output impedance to the load impedance. DC Servo Op-amp U2-C provides DC feedback to reduce the offset voltage at the amplifier output. Current limiting D2, D3, D5 and D27 clamp the voltage going into the transconductance stage which limits the output current. The clamping level is reduced when the amp is driven hard or when the thermal limiting circuit detects excessive heatsink temperature. Error amplifier Q30 sums the input voltage and the output voltage to create an error signal that drives the transconductance amplifier. Unlike a traditional amplifier the error amplifier has a low gain and as such the output voltage is loosely regulated. RadioFans.CN 收音机爱 好者资料库 HDII Power Supply Theory of Operation Overview Two Switch Mode Power Supplies (SMPS) provide regulated outputs to the main board and power amplifiers. The main board outputs are provided by a small “housekeeping” power supply that runs independently of the main supply. The three outputs are provided are 20 and +8. Linear regulators on the main board provide 15 and +5. The main power supply provides four outputs to the power amplifiers. To maintain a constant output power capability at 4, 8 and 16 Ohm loads these outputs change to match the load impedance selected on the rear switch. The nominal outputs are 30 and 45 for 4 Ohms, 45 and 60 for 8 Ohms and 60 and 90 for 16 Ohms. Four outputs are used because the amplifier is class H. In class H operation the lower voltage rails are used until the output voltage gets close to the rail voltage. At this point the high rails are switched in to provide additional power to the output. This operation dramatically reduces power dissipation in the amplifier. Line Filter: The line filter board is not attached to the power supply but it limits RF energy from being transmitted to the AC power lines. There are no active components on the board so most troubleshooting can be done by doing continuity checks. The black disk is a Negative Temperature Coefficient Resistor (NTC) or inrush limiter. When it is cold, it has a high resistance and limits the input current at turn-on. As current is drawn from the AC line, power is dissipated in the NTC and it heats up. As its temperature increases its resistance decreases and it ceases to limit current draw. Input rectifier: The input rectifier performs line frequency AC to DC conversion. There are separate configurations 120VAC and 240VAC. When connector J2 has a jumper installed, the unit is configured for 120VAC operation and should never be connected to 240VAC unit goes BANG! If the jumper is not installed, the unit is set for 240VAC operation and will not be damaged if connected to 120VAC. When the unit is configured for 240VAC, the large electrolytic caps, C1 and C2, are connected in series and the circuit operates like a typical full wave rectifier. When the voltage-doubler jumper is installed, the neutral is connected to the center point of the two caps and the line alternately charges C1 and C2 to the peak line voltage. Since the output is taken across both caps, the input voltage to the high frequency power converter remains the same for both configurations. Note that only two of the four diodes are used in the voltage-doubler mode. The two 47k 2W power resistors, R1 and R2 ensure that the capacitor voltages are balanced in 240VAC operation. High Frequency Power Converter The High Frequency Power Converter is a multi-output, two transistor forward converter with coupled output inductor quite a mouthful. The interested reader will find a much more detailed description in power supply literature. The Readers Digest version is: Both power transistors are turned on and off simultaneously at a 130kHz rate. When they are on, the input DC bus is connected across the primary of the transformer and reflected to the secondaries. This places voltage across the coupled output inductor and power is transferred to the output. The output voltage is regulated by increasing or decreasing the time the power transistors are on or Pulse Width Modulation (PWM). Two “catch” diodes are used to return any energy stored in the transformer back to the input capacitors. Current transformer T2 has a single turn primary and a 100 turn secondary. Using a transformer provides electrical isolation and allows a larger voltage proportional to current signal to be derived without excessive power dissipation. Gate Drive transformer T3 drives the gates of the primary connected power transistors from the secondary connected PWM chip. Small signal transistors Q13 and Q14 improve power transistor turn-off and reduce gate drive power requirements by not allowing the gates of the power transistors to swing negative. A zener diode is connected in series with the primary of the transformer to eliminate the possibility of saturation of the transformer core. When small signal transistor Q8 is turned off energy stored in the core of T3 cause the voltage to “flyback” but the voltage is limited by zener diode D40. Control Loop The control topology used is an average current mode control loop. Again the Readers Digest version. There are two loops used the “inner” loop is comprised of U4-C, U4-D and the secondary of current sense transformer T2. This loop attempts to maintain a constant average current whose magnitude is determined by the voltage loop. The “outer” loop is the voltage loop, which is comprised of U4-A and U4-B. This loop looks at a weighted sum of all four outputs and attempts to regulate this quantity. Currently the weights given to the lower rails is zero, so only the high rails are considered. U4-B scales the output voltage to a single voltage that is regulated by U4-A. U4-A regulates the output voltage by demanding more or less current from the “inner” average current loop. Note that the output voltage switching is done at U4-A by transistors Q9-11. PWM Control IC A UC3845 or UC3844 control IC is used to provide the PWM drive signals for the main SMPS. The UC384x family is typically used in peak current mode control but it is very low cost and readily available so we have “tricked” it into doing average current mode control. The timing ramp is scaled and used instead of the current sense signal, but the peak current is “ORed” into this pin to provide pulse by pulse current limit. Q6 and associated components provide a “soft-start” for the current loop while C13 provides voltage loops soft start. Thermal Shutdown PTC1 is a Positive Temperature Coefficient resistor whose resistance increases with temperature. These parts have a sharp “knee” in their resistance vs. temperature curve so they can act like a thermal switch. PTC1 is mounted on the output rectifier heatsink, so when the temperature threshold is exceeded Q7 is turned on and the output voltage is reduced. Housekeeping Supply Power for the main power supplies control circuitry and the digital and analog circuits in the rest of the system are developed in the housekeeping supply. It is based on the TOP234 integrated PWM IC. This IC contains the power MOSFET and all of the PWM control circuitry to run a power supply. See Mfg. Data sheet for complete explanation. HD II MAIN REV D.sch-1 - Tue Mar 06 13:37:04 2001 HD II MAIN REV D.sch-2 - Tue Mar 06 13:37:05 2001 HD II MAIN REV D.sch-3 - Tue Mar 06 13:37:05 2001 db_logic.sch-1 - Tue Mar 06 13:46:37 2001 db_logic.sch-2 - Tue Mar 06 13:46:37 2001 db_logic.sch-3 - Tue Mar 06 13:46:36 2001 HDII POWER SUPPLY BOARD Rev B.sch-1 - Tue Mar 06 13:50:45 2001 HDII LINE FILTER Rev B.sch-1 - Tue Mar 06 13:35:42 2001 HDII MIDI-SPKR-XLR OUTPUT REV C.sch-1 - Tue Mar 06 13:41:57 2001 HDII MIDI-SPKR-XLR OUTPUT REV C.sch-2 - Tue Mar 06 13:41:58 2001 HDII MIDI-SPKR-XLR OUTPUT REV C.sch-3 - Tue Mar 06 13:41:58 2001 HDII LED BOARD Rev C.sch-1 - Tue Mar 06 13:33:27 2001 LINE 6 Page 1 Flextone 2 HD Parts list 99 FLEX HD2 120v = Parent Item: 99 FLEX HD2 120 Flextone 2 HD Assembly 120V 1 21-34-0012 CABLE SIL FAB TO PRINT 10 EA .0 A Y N 1.000000 REV A INCOR ECO # 24102 120 21-34-1001Cable Assembly, FHD 210EA.0AYN1.000000 PWR-Main 10 pin 130 21-34-1002Cable Assembly, FHD 210EA.0AYN1.000000 Amp1-Main 10 pin 140 21-34-1003Cable Assembly, FHD 210EA.0AYN1.000000 Amp2-Main 10 pin 150 21-34-1004Cable Assembly, FHD 210EA.0AYN1.000000 Power Supply to Right Amp 6pin 160 21-34-1005Cable Assembly, FHD 210EA.0AYN1.000000 AC line-Power3 1 pin 170 21-34-1006Cable Assembly, FHD 210EA.0AYN2.000000 Amps-Out 2 pin 180 21-34-1007Cable Assembly, FHD 210EA.0AYN1.000000 Imp Sw-Main 3 pin 190 21-34-1008Cable Assembly, FHD 210EA.0AYN1.000000 Out-Main 3 pin 1100 21-34-1009CAB RIBBON DIL 26-PIN 2mm 710EA.0AYN1.000000 Z-TYPE 1110 21-34-1012Cable Assembly, FHD 210EA.0AYN1.000000 Power Supply to Left Amp 6pin 1120 21-34-1013Cable Assembly, FHD 210EA.0AYN1.000000 Power Switch to Power Supply 1 130 21-34-1021 CA SIL 3-PIN 1LG JUMPER HD2 10 EA .0 A Y N 1.000000 230V TO 120V (PIN 2 NOT USED) 1140 21-37-1160CABLE PWR UL/CSA SJT 18awg Blk10EA.0AYN1.000000 EL-302 w/gnd plug EL701 Sockt 1150 24-06-0011SWITCH,POWER,ROCKER, CHASSIS10EA.0AYN1.000000 MOUNT, OSLO RTP11A9C9 1 160 24-09-1301 SWITCH SLIDER 3-POS PNL-MNT 1ALPHA SS13010-0203-8T-011-NB 1.000000 LINE 6 Page 2 HD 2 Parts List = 1170 24-21-1122Flextone II SWITCH CAP10EA.0AYN1.000000 1 180 30-00-0305 SCREW M3 X 5 MM PHILLIPS FLAT 10 EA .0 A Y N 2.000000 BLACK 1200 30-00-0412SCREW #4-40 X 1/4 PHILLIPS10EA.0AYN2.000000 PAN BLACK 1210 30-00-0607SCR 6-32 x 7/16 LG PHILLIPS PN10EA.0AYN30.000000 H STL ZINC (W/ LK WASH) 1220 30-00-0632SCR 6-32 x .375 LG TAMPER RESI10EA.0AYN1.000000 STANT BLK 1225 30-00-1012SCREW #10-32 X 1/2 PHILLIPS10EA.0AYN4.000000 PAN ZINC 1230 30-00-1020SCR, 10-24 x 1 1/4 LG, OVAL CT10EA.0AYN2.000000 SK, PHH, STL, BLK Ref: Handle mounting to cabinet. 1260 30-00-1124SCR, 10-32 x 1 1/2 LG, OVAL CT10EA.0AYN4.000000 SK, PHH, STL, BLK 1270 30-00-1632SCR 6-32x3/8 PNHPHH TAP TITE10EA.0AYN8.000000 STL BLK 1280 30-00-4250SCR sheet metal pan head10EA.0AYN4.000000 slf tap. w/blk oxide 4 x.250 1285 30-00-9358SCR, NO.3, 1/2LG, OVAL CTSK PH0EA.0AYN4.000000 H, BLK (SUBST FOR 30-00-0358 1300 30-03-0001WASHER #10 EXTERNAL TOOTH10EA.0AYN4.000000 LOCKWASHER ZINC 1310 30-03-0011WASHER, FINISHING, NO. 10, CTS10EA.0AYN4.000000 K, BLK OXIDE 1312 30-03-1010WASHER #10 FLAT ZINC10EA.0AYN1.000000 1315 30-06-3232Threaded Hex Nut for 1/4 610EA.0AYN7.000000 pin stereo phone jack 1320 30-12-0200STANDOFF HEX 6-32 X 2.00 LONG10EA.0AYN4.000000 1340 30-27-0150FHD2 Lamp Lens Extrusion10EA.0AYN1.000000 1350 30-42-0035Overlay, FHD II10EA.0AYN1.000000 LINE 6 Page 3 HD 2 Parts List = 1 360 30-45-2000 KNOB PLASTIC 10 EA .0 A Y N 10.000000 1370 30