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Crown D-Series Instruction manuals
Crown D-Series: A Professional Powerhouse for Audio Excellence
The Crown D-Series amplifier delivers pristine, reliable audio performance for a wide range of applications, from live concerts to corporate events and houses of worship. With its advanced engineering and innovative features, the D-Series sets a new standard for professional audio amplification.
Key Features:
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Unmatched Audio Quality: Experience crystal-clear sound with extremely low distortion and noise, ensuring your audience hears every detail of your performance.
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Efficient Power Delivery: Class-D technology provides exceptional efficiency, reducing energy consumption and heat generation while delivering ample power to drive even demanding speaker systems.
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crown SECTION 7 MAINTENANCE 7.1 Introduction Section 7 contains technical information required to effectively and efficiently service and repair the Crown D- 150A Included are disassembly and reassembly procedures, required test equipment lists, checkout procedures, basic troubleshooting tips and a soldering technique review. : THIS INFORMATION IS INTENDED FOR USE BY AN EXPERIENCED TECHNICIAN ONLY! Use this information in conjunction with the Instruction Manual, schematic/board layout diagrams, parts lists and exploded view drawings (the latter located in Section 6 of this manual). | EQUIPMENT REQUIREMENTS Oscilloscope Capable of displaying a | 10M Hz signal Low-voltage resistance probe (100mv range). High-voltage resistance probe (1.5V range) | Volt-ohmmeter | (VOM) | Freq. Counter Sine/ Square wave available; flat frequency response. THD. ‚19% maximum | Signal Generator | Circuit Breaker - 15 ampere rating Peak reading meter (displays rms equivalent to a sinu- soidal peak for any wave form) | AC Line Voltage | Monitor APPLICATION 7.2 Required Test Equipment Many of the service and repair problems with the D-150A can be performed with a limited amount of test equipment. However, in order to return the unit to its “factory new” specifications, the following list of required test equipment is recommended. The “Requirements” column provides information to allow intelligent selection of substitutes if the “Suggested Supplier and Model” is not available or is considered impractical to obtain, Monitoring output during service and testing Check resistance values (low voltage probe). Check semi- conductor junctions for opens or shorts (high volt- age probe) Check DC voltages For accurate general monitoring Provide test signals for service and checkout In AC line to unit; " protects circuitry from overload if power supply has shorted Monitor Line voltage SUGGESTED MODEL Telequipment DS4A or equivalent Triplett 601 or equivalent Heath УМ ЗА Wavetek 130-Series or equivalent Available from CROWN 7-1 EQUIPMENT REQUIREMENTS Phase Meter | 100ту low range, flat fre- quency response to 100K Hz AC Voltmeter | Filter 20-20K Hz bandpass, low noise 20Hz-20K Hz Intermodulation Residual (.0029% or lower) | Distortion Analyzer 7.3 Soldering Techniques Note: Proper continuity between internal components of any electronic device is the key to its successful operation. Therefore, a brief review of the following discussion on soldering techniques may be in order. Because most service work involves component part(s) replacement, hand-soldering with the use of a soldering iron will be the only method covered, even though many exist. The difference between success and failure in service repair is often determined by the thermal characteristics of an iron and how well it matches the job at hand. One would not use a large flat-head screwdriver to work on a delicate Swiss watch. Likewise, the proper size iron and tip should be used when soldering delicate electronic parts in position. Iron wattage classification is actually not a very good method of choosing an iron. The reason for this is because of the possible inefficiency of heat transfer to the tip internally. A large wattage iron (125W) may, in effect produce lower tip temperatures than another iron smaller in wattage. Likewise, tip size and shape does not necessarily work in proportion to temperature. Therefore, it is impractical to compare soldering irons by their wattage but more feasible to refer to them by their maximum tip temperature. Usually, the skilled service technician can pick the right iran and tip for the job from experience o: recommendation. In most cases, the miniature or small electrical soldering iron will work well with delicate semiconductor devices (Fig. 7.1). When the proper size iron is used (usually around 700° F. tip temperature), a joint 1s almost instantly heated (approx. 500-550°) and application of iron and solder melting is simultaneous. 7-2 APPLICATION Set output level for test- ing; check noise level Between preamplifier and voltmeter in noise test Check IM distortion SUGG ESTED MODEL Hewlett-Packard 400F or equivalent Information available from CROWN Information available from Crown Fig. 7.1 Miniature Soldering Iron When clean metal is exposd to air a chemical reaction takes place known as oxidation. When heat is applied to metal, oxidation is speeded up and creates a non-metallic film that prevents solder from touching the base metal. By applying a small amount of solder to a hot iron tip, a desirable process known as tinning occurs. The main reason for tinning an iron is to help prevent it from oxidizing as well as to aid in heat transfer. Tinning should be performed prior to each use as well as after long idling times. To help prevent oxidation or remove existing oxidation while soldering, a natural rosin flux core solder should be used. Not only does flux aid in cleaning, but acts as a catalyst in that it helps speed up the joint formation without actually entering itself, into the bond. Never use an acid flux except to clean a highly oxidized tip that will not tin correctly. Crown recommends 63% tin/37% lead composition with a rosin flux core of 2.5% (melting temperature is approx. 361°F.). Fig. 7.2 shows the correct and incorrect method of applying rosin flux core solder to a joint. Never apply solder to the iron tip directly and allow solder to run onto the joint (flux is burned away and does not clean the joints). Always apply heat to the connection and allow the joint to melt the solder, not the iron. This insures proper wetting and flow of the solder. crown Fig. 7.2 Correct and Incorrect Solder Application Problem: Unsoldered wire. Characteristics: Properly assembled junction of wire, but One of the main advantages of using solder to make connections is that it is one of the few joining methods responsive to visual examination. This permits 100% inspection, while other methods require sampling and lengthy electrical tests. With proper inspection of materials used, soldering is the most reliable, time- proved, and versatile form of electrical joining offering the benefits of economy, dependability and speed. A good solder joint will have the following recognizable features: | | a) Proper wetting - mixing of molecules to form a singular, shiny bond of metal b) Proper flow - feathering out of solder c) Proper contour - outline of wire under solder d) Proper fillet - solder filling in holes and crevices. Because visual inspection is an important part of recognizing a good solder joint, the following examples have been provided to help with familiarization. without any solder. Fig. 7.3 Unsoldered Wire Cause: Solder not applied. Remedy: Correct amount of solder applied properly. 7-3 Problem: External strands. Characteristics: One or more strands of wire outside terminal. This defect most common when cup-type terminals are utilized. ig. 7.4 External Strands Cause: Poor assembly operation, too large diameter Remedy: Correct diameter wire tinned prior to insertion. wire used. Problem: Cut strands. Characteristics: Several strands of wire cut or broken and usually not soldered to terminal. Fig. 7.5 Cut Strands Cause: Improper wire stripping; wire flexed or bent Remedy: Use wire strippers similar to the one shown in excessively during or after assembly. Fig. 7.6 . Care must be taken to avoid nicking or cutting. Ig. 7.6 Wire Strippers crown Problem: Disturbed joint. Characteristics: Rough appearance with questionable adhesion. Fig. 7.7 Disturbed Joint Use of holding vice or similar tool to help Cause: Movement of wire/joint during cool-off stage. Remedy: prevent movement. Problem: Cold solder joint. Characteristics: Joint with dull, frosty appearance; often has poor adhesion as well as imperfect shaping. Fig. 7.8 Cold Solder Joint Cause: Too much heat applied (flux is boiled off before Remedy: Correct matching of iron/tip to specific job. oxide removal action takes place). CUTE | | Correct solder flux combination is also important. Problem: Rosin joint. TE Characteristics: Joint 1$ separated by a thin coat of flux producing high resistance to current. Fig. 7.9 Rosin Joint Cause: Solder applied previous to terminal reaching minimum temperature (solder melting point). When soldering individual component parts to printed circuit boards, several procedures may be followed. The following procedure complies to U.S. Government standards and may be altered to suit a specific situtation. |. Components leads should be bent to exact spacing of mounting holes in PC board (Fig. 7.10) . This allows leads to enter PC board at right angles and relieves stress. Fig. 7.10 Component Lead Spacing 2. Leads should be bent down tight to pad. 3. Leads should be bent in the direction of the run connected to the pad and clipped at a length approximately %” (Fig. 7.11). Fig. 7.11 Component Lead Bending 7-6 Remedy: Apply correct amount of heat; remove only after good wetting and fillet is achieved. 4. Components should be held tight to the PC board while clinching leads on other side (Fig. 7.12) and soldered accordingly. Fig. 7.13 shows acceptable solder joints. Fig. 7.13 Acceptable Solder Joints crows When soldering to lugs (as on potentiometers), the mechanical wire wrap should be a J hook with correct insulation clearance as shown in Fig. 7.14. Fig. 7.14 Soldering to a Lug Turret terminals also utilize the “J” hook (Fig. 7.15). Concentrate on good heat transfer to the terminal first, then the wire. If two wires are to be soldered, be sure of good solder flow to all three. Fig. 7.15 Turret Terminal Desoldering In order to replace a component part, it 1s often necessary to remove the old part by means of de-soldering. Several methods are available, the most common being the braided bare copper method. This wire is placed on the lead(s) of the component to be removed with the iron placed on top of the braided wire. This allows the solder to heat up while simultaneously adhering to the braid. When the braided wire is removed, the joint should be clean. (See Fig. 7.16) Fig. 7.16 Wire Braid Desoldering Next, use points of small diagonals to lift ends of component lead wires and remove the part. This procedure is applicable to both PC board desoldering as well as terminal and lug desoldering. Note: Be sure that lifting of the component lead does not also lift the copper foil pad from the board. Occasionally a small amount of heat will be helpful. Soldering is one of the most reliable methods of joining electronic component parts and assemblies. When properly used, it can be one of the most helpful tools in service repair work. 7.4 Basic Troubleshooting As is well known, time is an important factor in providing efficient service repair. Therefore, several time-saving troubleshooting steps are listed below. These hints may or may not already be implemented in your service work. If not, you may wish to experiment with them in order to help improve your efficiency. After all, time is money! A. Establishing Problems User complaints about defective operation may not always be clear or simple. Furthermore, the trouble the user has experienced may be due to the system and not the unit itself. If possible talk to the user about his problem. This will usually be simpler than trying to understand written complaints. À first hand account of the problem can help in: |) Getting the problem to re-occur on the service bench. 2) Getting an understanding of the probable cause. Some troubles will be obvious upon visual inspection. When the trouble (or its symptoms) is not so obvious ask: | a) Exactly what was the problem; how was it noticable? b) How was the unit being used? c) Has the system as a whole been caretully examined for possible external problems? d) How long had the unit been operating when the problem occurred? Was it heat related? If the user is unavailable or unable to explain the trouble the next step is a thorough visual inspection. B. Visual Inspection A good visual inspection may often save hours of tedious troubleshooting. Make a habit of proceeding in an orderly manner to insure that no vital part of the 7-7 following procedure is omitted. The visual inspection can be performed in 10 to 15 minutes. It is recommended both as a preventive maintenance procedure and also for its value in determining cause of malfunction. 1) Check that all external screws are tight and that none are missing. 2) Check all fuses/ circuit breakers. 3) Check for smooth and proper operation of switches, etc. 4) Inspect line cord for possible damage to cap, jacket and conductors. 5) Remove protective covers as outlined in disassembly instruction (Section 7.6). 6) Check that all attaching parts for internal circuits are tight and that none are missing. 7) Inspect all wiring for charred insulation, or discoloration as evidence of previous overheating. 8) Check that all electrical connections are secure. This includes wire terminals, screw and stud type terminals, and all soldered connections. 9) Check for obvious destruction of internal structural parts. Distortion in any of these parts could mean that the unit has been dropped or subjected to severe shock. 7.5 Discharging Instructions The D-150A amplifier employs very large-storage capacitors in the main power supply (C2, C3). For this reason, at any time the covers are removed it is necessary to discharge these large capacitors in order to avoid possible damage to the unit and also to prevent shock hazard. This is best performed by placing a 50 ohm/ 10 watt resistor across capacitor terminals shown in Fig. 7.17. Always use extreme caution while handling the discharge device. Fig. 7.17 D-150A Discharge Points 7-8 7.6 Disassembly for Inspection, Service, Testing, Adjustment and Repair The extent of disassembly required will depend upon the extent of inspection, service, testing, adjustment and repair to be performed. Illustrations referred to in parenthesis (index numbers) are located in the parts list (Section 6) of this manual. The D-150A amplifier is specifically designed for easy servicing. It may be partially disassembled and still be made operational for bench testing and servicing. This may be accomplished by removing the front panel, transformer cover and wrap-around, and the board electronics cover (Section A). These steps provide easy access to nearly all major components of the amplifier. Those that are not now accessible for servicing can be removed following the procedures given for replacing individual assemblies. Caution: DO NOT attempt component replacement or other repairs with power applied. Always follow discharging instructions (Section 7.5) to prevent possible circuit damage or serious shock. A. Removal of Front Panel, Transformer Cover and Wrap-Around, and Board Electronics Cover 1. Remove four socket head screws (7), two from each end of the rack ears (6), and remove the six phillips front panel mounting screws (30). 3. Remove two screws (15) from the top of the trans- former cover (14), and remove the transformer cover and the transformer wrap-around (13). 4. Remove two screws (33) from the top of the board electronics cover (17) and remove the cover. 5. Reverse the above sequence of actions to reassemble the amplifier covers. B. Removal of Control Plate Assembly |. Remove board electronics cover (17) as described in paragraph À, Step 4. 2. Remove two screws (42) from top of control plate assembly. 3. Carefully lift control plate assembly and turn nearest edge (where screws were removed) upward until bottom of control plate is accessible. Do not place unnecessary strain on wiring connected to main PC board. 4. Input jacks (39) are now accessible for replacement. C. Replacement of Components on Main PC Board I. Remove board electronics cover (paragraph A, Step 4). Both component and solder sides of board are now accessible. | 2. Carefully unsolder and replace (with identical parts) any defective components. crown Caution: Use normal soldering precautions. DO NOT use excessive heat; heatsink adjacent components to prevent damage. 3. The IC is a plug-in component. 4. Resistors R128, R228 (selected bias resistors) are plug-in components. 3. Disconnect four Faston connectors from terminals of bridge DM-1 (66). 6. Reconnect four Faston connectors to terminals of bridge DM-1. 7. Replace front panel (paragraph A, Step 2). 8. Replace transformer cover and transformer wrap- around (paragraph A, Step 3). D. Replacement of Input Level Potentiometers (R 105, R205) G. Replacement of Filter Capacitors, C2 and C3 |. Remove board electronics cover, paragraph A, Step 4. 2. Remove front panel, paragraph A, Step 2. 3. Unsolder and tag for identification all leads to the terminals of input level potentiometer (27). 4. Remove control nut (2) using a 4” nut driver and remove defective R105 and R205 from the front panel (5). 5. Solder leads removed in Step 3 to terminals of new input level potentiometer (27). 6. Place new potentiometer in position and replace control nut (2). 7. Replace the front panel. 8. Replace board electronics cover, paragraph A. Replacement of Thermal Switch, SW-1 1. Remove front panel (paragraph A, Step 2). 2. Remove board electronics cover (paragraph A, Step 2). | 2. Remove board electronics cover (paragraph A, Ste 4). 3. Disconnect two Faston connectors from terminals of thermal switch SW-1. 4. Remove two each, screws (51), hex nuts (45), star washers (46), solder lugs (50) and remove thermal switch SW-1 from the chassis. 5. Place new thermal switch SW-1 (49) in position and replace hardware removed in Step 4. 6. Reconnect two Faston connectors to terminals of new thermal switch SW-1. 7. Replace board electronics cover (paragraph A, Step 4). 8. Replace front panel (paragraph A, Step 2). F. Replacement of Bridge, DM-1 |. Remove transformer cover and transformer wrap- around (paragraph A, Step 3). 2. Remove front panel (paragraph A, step 2). 1. Remove front panel (paragraph A, Step 2). 2. Remove transformer cover and transformer wrap- around (paragraph A, Step 3). 3. Remove one Faston connector from filter capacitor (C2 or C3) terminal. 4. Remove two screws, (60), one solder lug (62), two panel washers (65) and two fiber shoulder washers (64) from the filter capacitor terminals. 5. Remove defective filter capacitor (C2 or C3) from the chassis. 6. Place new filter capacitor in position and replace hardware removed in Step 4. 7. Reconnect Faston connector to filter capacitor terminals. 8. Replace transformer cover and transformer wrap- around (paragraph A, Step 3). 9. Replace front panel (paragraph A, Step 2). Replacement of Output Inductors, L101 and L201 1. Remove front panel (paragraph A, Step 2). 2. Remove board electronics cover (paragraph A, Step 4). 3. Unsolder one end of brown coil wire from the out- put binding post terminal and the other end from the adjacent driver transistor terminal. | 4. Remove hex nut (52), nylon washer (53) output coil toroid core and brown wire (54). 5. Place new output coil toroid core and new brown wire in position and replace hardware removed in Step 4. 6. Solder one end of brown coil wire to the output binding post terminal (55) and the other end to the adjacent driver transistor terminal. 7. Replace board electronics cover (paragraph A, Step 4). 8. Replace front panel (paragraph A, Step 2). 7-9 |. Replacement of Driver and Output Transistors |. Remove front panel (paragraph A, Step 2). 2. Remove board electronics cover (paragraph A, Step 4). 3. Unsolder and tag for identification all wires and component leads connected to transistor terminals. DO NOT unsolder leads attached to solder lugs mounted on transistors. 4. Refer to detail drawings of output and driver transis- tor and remove hardware shown and the defective transistor. 5. Coat both sides of the insulator (86,91) between the transistor case and the chassis with a heat-conducting compound (Z5 silicon compound). 6. Install new transistor and tighten screws and hex nuts snugly to assure good heatsinking. 7. Resolder wires and component leads removed from transistor terminals in Step 3 above. 8. Replace board electronics cover (paragraph A, Step 4). | 9. Replace front panel (paragraph A, Step 2). Replacement of Power Transformer, T-1 I. Remove front panel (paragraph A, Step 2). 2. Remove transformer cover (14) and transformer wrap-around (13) (paragraph A, Step 3). 3. Disconnect seven transformer wires that pass through the hole in the chassis beside the transformer base. a. Two red wires; remove Faston connectors from DMI terminals and remove Faston connectors from the red wires. b. One yellow wire; unsolder from solder lug (62) at junction of capacitors C2 and C3. | c. One black and one white wire; unsolder from terminal strip (68). d. One black/red wire and one black/white wire; unsolder from terminal strip (68). Input Signal Type of Test/ Adjustment Characteristics |. Quiescent DC offset None 2. Bias Adjustment None 3. Power Test (one channel driven)1 volt; 1K Hz sine wave 7-10 4. Pull all wires back through hole in chassis. 5. Remove hardware securing transformer T1 to the chassis: a. Remove four hex nuts (70). b. Remove four star washers (71). c. Remove pilot light assembly (73, 74). d. Remove terminal strip (68). e. Remove rubber grommets (81). f. Remove four transformer mounting screws (72). 6. Remove defective transformer T1 (75). 7. Cut leads on new transformer T1 to same length as those on the transformer being replaced. 8. Place new transformer TI in position on the chassis and replace, in reverse order, all item removed in Step 5. 9. Pull bottom side of chassis. 10. Connect seven transformer wires to destinations shown in Step 3 (also see Section 7.10). I'l. Replace transformer cover and transformer wrap- around (paragraph A, Step 3). 12. Replace front panel (paragraph A, Step 2). 7.7 Reassembly Reassembly 1s essentially the reverse of disassembly. Ifin doubt about types and sizes of attaching parts, refer to the appropriate illustration in Section 6. 7.8 Electrical Checkout and Adjustment Procedures The following chart outlines an orderly checkout and adjustment procedure for the D-I50A. The equipment required to perform the various procedures is listed in Section 7.2. Comments A. DC millivolt meter is connected to amplifier output. Input level controls are fully counterclockwise while off- set controls (R105, R205) are ‘adjusted for zero volts at output. | В. Input level controls are at twelve o'clock (or ajusted for maximum DC offset). Offset controls (R 103, R203) are adjusted for zero volts at output. Positive output, base-emitter junction should be between .3V and .35V. It is altered by selected resistors R128, R228; they are typically between 92 and 240 ohms. Into 8 ohms, 28Vrms (98 watts) should be obtainable. before signal clip. Into 4 ohms, 26.5 Vrms (175 watts) should be obtainable before signal clip. all transformer wires through chassis hole to Crow 4. Protection Circuitry | volt; LKHz Into 2 ohms, 39Vrms should be obtainable before signal sine wave clip without a load. 5. High Frequency | volt; TOK Hz Into an 8 ohm load, a 30 volt peak-peak square wave square wave signal should exhibit no ringing. | volt; 20K Hz Into an 8 ohm load, a 27Vrms signal should exhibit no sine wave ringing. 6. Intermodulation Distortion .5V £2%: 60Hz- — (See Fig. 7.18) When using the Crown IMA, typical 7K Hz signal readings will be as follows: summed in 4:1 0dB = .0049% (20 volts out) ratio through -25dB = .01% through -40dB = .03% Note: All distortion readings must be below .01;. 7. TOC 2.5V peak-peak ¡OC lights should illuminate once for every rise time and .5Hz square wave once for every fall time (twice every full cycle). Test generator rise time must be less than 1.0 microsecond. 8. Signal to Noise (See Fig. 7.19) Signal to Noise should be 115dB below rated output with meter bandwidth of 20Hz to 20K Hz. 9. Quiescent AC Power 30 watts at idle as monitored by wattmeter on AC line: 250 watts full rated output. (100 MICROVOLT SCALE) | a AC VOLTMETER 7 | 20-20 KHz RETURN UNGROUNDED- WRAPPED AROUND OUTPUT CABLE LOW NOISE | FILTER D-150 A EITHER (LEVEL CONTROLS; MINIMUM ) re | CHANNEL (INPUTS DISCONNECTED) = ое OUTPUT EITHER OUTPUT CHANNEL Fig. 7.18 IM Distortion Test Set-up 7-11 AC | SIGNAL | DIGITAL | sioner | [outers | GENER ATOR COUNTER | | 20-20 KHz | | LOW NOISE | FILTER | POWER |! | SUPPLY | MONITOR | | & VARIAC | EITHER CHANNEL D-150A AMPLIFIER Fig. 7.19 Signal to Noise Test Set-up 7.9 Troubleshooting Hints Symptom Defect Blows Fuse |. Rectifier block shorted, DM 1 2. CI shorted 3. Leaky or shorted filter capacitors C2, C3 4. Bootstrap supply AC wire frayed and shorts to positive supply trace on Main Board Shorted power transformer TI A shorted power device in both positive and negative output stage QI110, QI114, Q210, Q214 7. Fuse blown due to external problem - wrong size fuse inserted > 8. Pinched wires in power supply No Output Stage Bias |. No bias resistor R128, R228 2. Bias resistor connector to circuit board not soldered 3. L100, L200 open 4. C-E short of bias transistor Q111, Q211 High Bias (amplifier heats up) I. Amplifier instability-high frequency oscillation (check Q106, Q206) 2. Shorted output terminal post DC offset (see offset section) 4. Leaky output device (may pass signal and show okay with continuity test) Q110, Q114, Q210, Q214 ‘о 7-12 Symptom Negative Offset -Both Channels- Positive Offset -Both Channels- Positive Offset -Single Channel- Negative Offset -Single Channel- Small DC Offsets Negative half of Signal missing Positive half of Signal missing Oscillation (Full waveform) Oscillation (Positive half) crown LW DN) me bg wen % » NAB WD = Pod ps + * N OS SUN Defect Defective IC op amp (UA739) DS shorted QI101, Q201 leaky or shorted Defective IC op amp (UA739) D4 shorted Defective 1C op amp (UA739) Q100, Q200 leaky or shorted QI01, Q201 open Q106, Q206 open, leaky or shorted Q105, Q205 open leaky or shorted Positive predriver, driver or output device leaky or shorted Q107, Q207, Q109, Q209, Q110, Q210 Q111, Q211 shorted Defective 1C op amp (UA739) Mono switch hot wire shorted to ground Negative predriver, driver or output device leaky or shorted О112, Q212, Q113, Q213, Q114, Q214 О101, Q201 base to collector leakage Broken ground on input level control (R105, R205) Input jack hot lead and ground pin not shorted together (level controls full up with no input jack) D100, D200 leaky or shorted Q112, Q212 open Violet/ white wire from main board to output board open or not soldered Bootstrap supply a. C4 open b. DI! or D2 shorted c. Green AC wire not soldered correctly QI101, Q202 open Loss of positive supply voltage (+45V) D3 shorted Q108, Q208 open, leaky or shorted Q107, Q207 open R132, R232 open Yellow/ white wire from main board to output board open or not correctly soldered R106, R206 open C116, C216 open Defective IC op amp (UA739) Defective driver, Q109, Q209 C113, C213 open 7-13 Symptom Oscillation (Negative half) Protection Circuit - No current limiting -Excessive limiting -Current limiting oscillation- -Flyback pulses from inductive loads - Clipping (negative) Both Channels Clipping (positive) Both Channels Clipping (positive) Single Channel Clipping (negative) Single Channel High IM (Load Related) Low dB IM 7-14 Load Pd ана fumas # SON “No enmity, + pen a RENE ave — A» AN > Y NY = меню AN a вон D Pen [3 Defect Defective 1C op amp (UA739) C112, C212 defective Defective driver, Q113, Q213 Current limiting transistor open a. Positive (Q103, Q203) b. negative (Q104, Q204) D101, D107, D201, D207 open R119, R118, R219, R218 open C108, C109, C208, C209 open D101, D107, D201, D207 shorted Q104, Q103, Q204, Q203 shorted Loose output hardware Negative feedback capacitor, in limiting transistor circuit defective, positive C107, C207, negative C110, C210 C108, C109, C208, C209 open D5 leaky or open Q2 leaky or open Defective IC op amp (UA739) D4 open or leaky D3 open or leaky Defective IC op amp (UA739) D1 or D2 open (positive portion of signal will clip at a 60Hz rate) C4 open or changed in value Open or leaky predriver, Q107, Q207 Shorted or leaky limiting transistor О103, Q203 Open output emitter resistor R132, R232 | Defective IC op amp (UA 739) Q102, Q202 defective Open or leaky predriver Q112, Q212 Shorted or leaky limiting transistor Q104, Q204 L100, L200 open Open output emitter resistor R134, R234 Q115, Q116, Q215, Q216 on IOC board defective R9 (1 ohm) open Defective IC op amp (UA739) C101, C201 open С114, C214 open Q106, Q206 defective Defective predriver or driver device Q107, Q207, Q112, Q212, Q109, Q209, Q113, Q213 Low output Bias ‚ С102, C202 open C104, C204 open crown Symptom Defect High IM (Not Load Related) |. R115, R215 changed in value 2. R109, R209 changed in value 3. C105, C205 changed in value 4. C106, C206 changed in value 120Hz in output waveform 1. Power Supply filter capacitor(s) open, C2, C3 2. C5 open 3. Power Supply filter capacitor mounting hardware loose High noise 1. Input jacks not isolated from chassis ground 2. Noisy zener diode, D3 3. Broken ground on input jack, in input cable or on input level control (R105, R205) 4. Oscillation (C101, C201 open) 7.10 Voltage Conversion Instructions Often Crown products are purchased in one country and E Е El |: later transported to another requiring an AC mains 100v Г | conversion. For this reason the following AJ LI IS Pel chart/explanation as well as a world-wide voltage map x © | (in the rear of this manual) is provided. SÉ IP 3 3 [a2 The D-150A power supply may be connected for any of 1200 | | five voltages. Converting from one to another can be В Це accomplished with a soldering iron and a pair of wire strippers. Observe the following instructions: Z 1. Remove the two rack ears from the front panel. = 200 2. Remove the front panel/ bottom cover (See Section AU bel 7.6A). a Tia |» za la 3. Position the front panel to gain access to the \ transformer leads. Locate the two terminal strips 200 OO (terminals A,B,C, D and E). = a © 4. Determine the correct connection from Fig. 7.20 and T $ Tx solder the leads accordingly. al ie 240V 5. For all connections 200VAC and above, the line fuse La] LJ le le) F1 is changed from 6.25 amps to 3 amps. 6. Carefully check all connections, then repeat steps | and 2 in reverse. Fig. 7.20 Voltage Conversion 7-15 7.11 Block Diagram Circuit Theory The following discussion refers to the block diagram in Fig. 7.21. The input amplifier is the initial stage of circuitry that establishes the fixed gain of the D-150A. The input bias compensation stage, directly related to the input stage, helps control any DC drift that may occur with a unique temperature-controlled circuit. The IOC (Input Output Comparator) circuitry works in conjunction with the error correcting signal of the main op amp. Any time a small “non-linearitv” exists in the amplifier, an error signal appears at the output of the main op amp (via the fedback loop of the unit). This produces an abnormally high value, exceeding the “window” of the IOC and illuminating the LED. Since transient overload can happen rapidly, a pulse stretching circuit is added so the eye can detect the LED lighting. The signal translator stage combined with the last voltage amp form the voltage amplification stages of the D-150 A. Virtually no voltage amplification is performed beyond these stages. Current amplification circuitry consists of basically three stages: the Predriver, the Driver and the output transistor stage. Connected to these stages, is the protection circuitry which is activated when a predetermined amount of voltage and/or current is drawn across the output stage sense resistors. This protection signal is then in turn fed back to the limiting circuit which limits any increase in the bias servo voltage to the power devices. The power supply is a continuous-duty type. The main DC supplies are full-wave capacitor input type with heavy duty, chassis heat-sinked diodes. The input amplifiers are powered by zener-regulated power supplies. The bias regulators are also powered by zener- regulated current sources with the result that line voltage variations do not cause noise or distortion due to mis- biasing. INPUT COMPENSATION N FOSITIVE POSITIVE > DRIVER | OUTPUT STAGE STAGE a : ] - LAST INPUT SIGNAL №. BIAS PROTECTION AMP | TRANSLATOR VOLTAGE SERVO CIRCUIT CH.1 af, INPUT | | T4 ie ; NEGATIVE NEGATIVE DRIVER >> OUTPUT STAGE STAGE INPUT OUTPUT COMPARATOR CH.10UT $ 10K / r > $ --d § Co | ¡MONO L - - | = = ST. 7 MONO --Q LS CH.20UT INPUT IAS : POSITIVE POSITIVE COMPENSATION > ORIVER > OUTPUT STAGE STAGE 4 , | ao E > | 7 INPUT e SIGNAL __ > VOLTAGE BIAS PROTECTION L — | CH. 2 AMP TRANSLATOR AMP SERVO CIRCUIT INPUT” + Рот PL x j 4 | NEGATIVE N NEGATIVE 1 era DRIVER OUTPUT | INPUT STAGE STAGE QUTPUT COMPARATOR Fig. 7.21 D-150A Block Diagram 7-16 crown 7.12 Theory of Operation | The following explanation refers to schematic diagram MI-261E located in Section 6. However, each circuit under discussion is reprinted below in order to aid in circuit familiarization. Only channel 1 is shown for simplicity. A. Input Stage After entering the unbalanced 7” input jack, the input signal level is adjusted to a desired input amplitude through RI0S and then applied to the dual IC operational amplifier (IC1A, IC1B). Thisopampisa low noise, large gain bandwidth type which results in usage of feedback cirucit loops throughout and ultimately, extremely low distortion values. The direct input signal is applied to the non inverting input (pin 5) of ICI A and the feedback signal is applied to the inverting input (pin 6). Both signals entering СТА will be in phase with each other because of the feedback path and will thus produce an output (pin 1) of almost zero. The IC op amp will always try to keep a zero potential difference between both inputs. Any type of non-linearity will cause the op amp to produce a large output, and therefore a substantial size correction signal in order to rétain the small output level. HOV © IRPUT/OBFSET || dai == D4 Rig? > R102 55 > pao 250K LOG q = > 4 I css Do SS ser = @100 р | < < 4 R137 ¢ © RIM 1808 < < IK ый 1.750 las C108 TT ar ; A108 < SEE NOTE < S ouTPUT | OFFSET =m SR Ee SER Ee SE cof AE AS An Fig. 7.22 Input Stage B. Voltage Amplification The operation of the D-150A front-end circuitry (IC op amp through QI05) is to basically provide voltage amplification. However, the signal translator transistor (Q101) provides no voltage amplification itself, but rather converts the ground referenced input signal to a signal with a reference to the negative supply (-45V). The result is higher voltage swing capabilities from QI05 (final voltage amplifier). The final voltage amplification transistor (Q105) is the main source of voltage amplification in the D-150A. R116 in the base circuit of this transistor serves two purposes: 01 | |) it provides collector current for О101 2) it allows the signal on the collector of QIOI. to be developed across it and thus amplified. As this development is in process, Q105 emitter voltage is developed across R124. When this voltage reaches a positive .6V, Q106 turns on and “pulls” the drive away from the last voltage amplifier, thus acting as a current limiter for Q105. Rí07 i < se < 8108 $ An cos < < Rig © IK ow wine C104 = arr R115 к > se C185 R108 * > e 120PF 510 y Y > 1% § a D } wes СТОБ = 00PF a105 © AAA al ati 18K 1% $ € nié aies | 2 ga < Ris < ae 31 < 9 — } | | “ой Voltage Amplification Stage 7-17 crown SECTION 8 SERVICE BULLETINS Periodically, a situation may arise where Crown will feel that it is necessary to change or update specific circuitry by the addition or subtraction of component parts. This information is automatically sent to all Crown Warranty Service Stations. It should be kept with this manual, preferably behind this page as indicated by the note at bottom. Should there be any question pertaining to these changes or updates, call or write the Crown Technical Service Department. PLACE ALL SERVICE UPDATES HERE 8-1 — 4 THERMAL T ey SWITCH ORN BLKWHT JP 00 — юг me | +] | INTERNAL FUSE F2 YEL | a ca | | R10 10/160v D2 | AA A М в! +100V LINE FUSE | 1 nm, | ; > C5 F1 RED + A = | R110 D1 22e SF mov R210 L + 24K Î +70V 2.4K 7 == 6400/50v | — MM — A AAA BLK —\ AJ | | a D3 = RED 0102 0202 GAN + 45V 4— e + — + 45 = WHT rh 1 ™ < 7 mM aa ств | $ 25 2° hal T + 1.45v p Pw N + 1.450 = —— $ POWER SUPPLY SHOWN WIRED FOR 120VAC LINE, = YELMHT R4 En — m 33VAC 0709 Une Y D102 200K $ $ Nk x D202 < Te <a — - i VAA sv A a. он 0110 > 7 | эк J с? D103 100/12v D203 a103 0203 Г + .34v | ‘ RY. N—4 >t 4 ) +—k e Т q р id 4 В BTAS SETTING ; R117 4 = R217 5% > BIAS SETTING 111” | mS Tw m3 FW $ г HT La | | A gh "| | BRN/WHT A 5% Sk + | | A ho | BRN/WHT NA A N— € | R118 = = C208 R218 | + Pre om м | E > R132 | в № 5.6K +10V sex | p 5%. RED E + 45V > 1 | pe —————— | || , FAN a И a dm — AA ii | : > R232 THERMAL Ti > SW < R125 ` € : SWITCH > R120 _ и OFFSET INPUT OFFSET * R220 $ Ras > BW R233 ORN BLK/WHT 27" | 00 3 ге | ca Y ows oF oe 4 5107 > es = R202 } R207 R213 0205 Ÿ six $ ME 0.000 27 — e men 0.00v 1w > R106 260K LOG 250K LO R208 < 8.2K 1w г , BAN RED + AA = in ата Nee eed) » ou X + 2.350 AN S a ¢ эк © в УФ 2,350 К D204 ¢ bean Nem = AA | R121 R113 c200 R221 | | = SL 00/50 | ena = 7 Y pro 25/18 BH == er = 0100 | 0200 = 0208 == 26/16v Ds Y a => ca13 NP ; INTERNAL FUSE F2 YEL L101 5% R201 = L201 | ‘ [0 N | 3UHY | il AN il pr $ Ато! M $ || AAA il | JUHY — < | = oe Зо Yo | me 82 | gq w 7 EE wm | Wow m3 mt LINE FUSE | — A $ Bw 120 5% $ > 175 | 175 M $ 5% 120 WS RED + 1.75 + 1.75 FI — = À J cm TU NAN Q101 Ч. TS его! A | == | L_ M сз = “01 $ he Too cmo c210 ol cz подв = CHANNEL? x == 9400/50V CHANNEL 1 > == со LÀ co R100 A200 001 == = 0022 < 780 OUTPUT MN He NM Nn A| [x | To" y | 100k Sa cm A 44 MN nN / me | À SRN ] $ 29 > 3 L100 ated SEE NOTE $ 4 $ Y sEENOTE TPF T 0204 { 4 | RI 128 R127 > >. > " , 35" SEP 307 Jun | my | TS ame Su y Iw Sa pe À w | — | LA b> - 45V = | q ore .004v POWER SUPPLY SHOWN WIRED FOR 240VAC LINE. ) . и EE 33VAC | == Ne | | | YOK > - C205 < R216 % 2 T ТОРЕ 510” 120PF == > 1% Li я NOTES: lee AD § 3m, Jl | anz 64v 4 = Ww = - 64v - THIS SCHEMATIC APPLIES TO AMPLIFIERS NUMBERED jp € == co or == € SN8359 TO SN17875 (SELECTED UNITS). wont Lou va _ —| > - DC VOLTAGES ARE SHOWN FOR VARIOUS POINTS. THESE | + 1 ет» Г | |: mm = 4 4 ARE THE NORMAL OPERATING VOLTAGES FOR ZERO air ss | as | 3 200 — — | || R136 Î , + } INPUT. | < os | 310 #124 $ a = — . Iv Г $ Raa Зи 5W w + 4 - THE HEAVY CONTINUOUS TRACE FOLLOWS THE PRIMARY = 45V +— ¿ —d y ) A AH Mm 4 1 > gy SIGNAL PATH THROUGH THE CIRCUIT. THE HEAVY | |. BROKEN TRACE SHOWS FEEDBACK PATHS. - WIRE COLOR CODES ARE GIVEN FOR THE MAIN POWER SUPPLY AND SOME BOARD WIRES. - ALL RESISTORS IN OHMS UNLESS OTHERWISE STATED. - ALL CAPACITORS IN MICRO-FARADS UNLESS OTHER- WISE STATED. - COMPONENTS COMMON TO BOTH CHANNELS ARE NUMBERED FROM 1 TO 99. - CHANNEL ONE COMPONENTS ARE NUMBERED FROM 100 TO 199. - CHANNEL TWO COMPONENTS ARE NUMBERED FROM 200 TO 299. - FOR MONO CONVERSION TIE POINT A TO B AND C TOD. - R108 AND R208 SHOULD BE 3.3K, WW WHEN IC! IS NA749. Fig. 6.1 M1-261 Main Board Schematic l— CHANNEL 1 INPUT R105 25K LOG —ojos i — ——— _——]]Ál-——]] ]———]]—. —— "===" i—Ñ]]]ÑÚ He R205 < CHANNEL 2 26K LOG * THERM. COUPLED TO HEAT SINK cron oso Laboratory Power Amplifier MI 261 NPC OUTPUTS ia 390 — 5 Ce | о MON TO NELS NUM VN R108, 208 ARE OMITTED WHEN IC-1 1S uA739; 3.3K WHEN uA749 IS USED. Fig. 6.2 MI-261 Foil Board Layout Bl THERMAL T1 vu + 46V SWITCH ORN BLKAWHT PP 0 | ee, а RED г 3svac || I a | TT" 9400/50V INTERNAL FUSE F2 YEL | J ‹ i = el R10 10/150V D2 | Í ' a AA KH „а +100V | | Y YY И + vi LINE FUSE — 1 Ф в tl CS Fi RED | o ; = R110 & 0 2x TT 10/50v R210 | 4K L ай em сю ен ным — 4 + |. cs . AAA TN +70V ZN. AA == 8400/50 | BLK x Da ; SN ST — ‘ RED 102 0202 — GRN A +45V + + + = + — + 46V < — WHT 7 4 BLU cus 1 $ 53, eas a -usy ; T + 1.450 p PW + 1.45v = mi bh JM — POWER SUPPLY SHOWN WIRED FOR 120VAC LINE. R4 a108 Y D102 200K $ < o Y ox T TH 3IVAC Ч x 1 1 +sv a = = —Ñ ANA E — И — m ano эк de C7 D103 atos J T 100/1724 0203 D203 : + ‚у ‹ К a в — | . BIAS SETTING | Qn Ca > C107 | 4 = с217 | | c207 Sn e 3 BIAS SETTING BANMWHT A | sm | 58K $ | 1 | 5% | | BRN/WHT R118 R119 > C108 = = c208 > R219 R218 | | = 82 < НЫ R112 R212 | da 2 2 oe < 6.6K 5.6 RED + “sy $ haz | tr ) | AAA +10У И 2 ae y AY || | —— S R232 oui EW < $ A SWITGH n ho $ 220 I ER Y 0105 св == ыы я” во) J INPUT OFFSET INPUT OFFSET 0208 Y R220 > #25 $ EN R233 ORN BLK/WHT y 1/2NMF 5% a T > R202 : R207 nas q © 12wme 27 | — Xr + RED Mn nn == A = J WW |] © 2 a N 250K LOG 8.2¢ Ww | > 0.00v BAN zw ; py ГУТ D104 2.35 AAA Ро AA * 2.35 2 D204 or] = 26. Ann | | | | 8121 X C109 ana 103 | Bons у coo К | en | AN + — - — = — iaa | =F Shor o E | Be T= = m A к | Отв wr | А = a аи INTERNAL FUSE F2 YEL | 3UHY o it 1 Jl A Il ЗОНУ | { — Ci Y Y | = 2M « N Y Il | I 7 | A122 4 > < cm rss | | ih You | me E | 3 ‘ w $ SE? ве ¥ oo ms qe F1 RED EA I 1 T | Ч % > La 1 + 1.75v À + 1.750 La! > 5% 5% A | > Va 4 = > — —— AN 0101 0201 AA dé —k Lo ' 1 $ cH12 ey r A ™~ VV "azi L i < 8128 = = р — == == — == — - toc снАММЕС — < 760 p 0022 = C110 сго dn aden C212 2 R226 = CHANNEL 2 BLK = 9400/50V OUTPUT Г 001 + c104 R100 R200 | 001 == T= 0022 < 760 OUTPUT == Ра НИ Mu MM sf (I d m 47PF р101 100K D201 À x Mn = sem € ww E J DU Emo = dd Tw | —T— GRN R129 R128 > R127 L100 > > > WHT 7 Z se. 2 5MHY Dos Y | f ore 2— Y 020 . L200 $ ma; {7 A BLU mM [ m= our | 820K - pte - 45у .004v .004v POWER SUPPLY SHOWN WIRED FOR 240VAC LINE. | mM / N =v e 33VAC 1 | + D5 RUG Ш = R209 « ET Y mE 35 LP) q 1% < 1% S 1% | D ) $ ox “В” 1 A | NOTES: an | | + Зы = {| | us € == oo sor € - THIS SCHEMATIC APPLIES TO AMPLIFIERS NUMBERED Lon J | E И coa = 200PF = — 200PF SN8359 TO SN17875 (SELECTED UNITS). й И | L 1 C211 = 470PF 470PF - DC VOLTAGES ARE SHOWN FOR VARIOUS POINTS. THESE a 4 ve | $ те не $ | ого я . < 820 « It ARE THE NORMAL OPERATING VOLTAGES FOR ZERO f $ tf 1 ‘ R124 € 9 > R224 INPUT. +70 ва < + = e 2 82 „310 = 45V #+— y + } mM Ча A N y + } > — av - THE HEAVY CONTINUOUS TRACE FOLLOWS THE PRIMARY q SIGNAL PATH THROUGH THE CIRCUIT. THE HEAVY | BROKEN TRACE SHOWS FEEDBACK PATHS. nn lA e > —— o _— | _ —] - WIRE COLOR CODES ARE GIVEN FOR THE MAIN POWER | > 27 Roses SUPPLY AND SOME BOARD WIRES. + - ALL RESISTORS IN OHMS UNLESS OTHERWISE STATED. Fig. 6.3 MI-261A Main Board Schematic - ALL CAPACITORS IN MICRO-FARADS UNLESS OTHER- | — A y A AM Crown o/s WISE STATED. | e hoo = super? - COMPONENTS COMMON TO BOTH CHANNELS ARE Laboratory Power Amplifier NUMBERED FROM 1 TO 99. - CHANNEL ONE COMPONENTS ARE NUMBERED FROM 100 MI 261A TO 199. | FAIRCHILD OUTPUTS - CHANNEL TWO COMPONENTS ARE NUMBERED FROM 200 TO 299. - FOR MONO CONVERSION TIE POINT A TO B ANDCTOD. - R108 AND R208 SHOULD BE 3.3K, :W WHEN ICI IS NA749. He 0 BOTH CHANNELS NUMB & A м @ | © LEFT CHANNEL ONLY: RIGH SUN E | 8 WN a R108, 208 ARE OMITTED WHEN IC-1 1S uA739; 3.3K WHEN uA749 IS USED. Fig. 6.4 MI-261A Foil Board Layout
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