WhitakerAudio 60 W Stereo Power Amplifier User And Assembly Manual Download Page 3

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Table of Contents

Circuit Description

1.1 Power Supply

1.2 General Considerations

Parts List

PWB Design

Construction Techniques

Step-by-Step Instructions

5.1 Assembly of Right Channel PWB

5.2 Assembly of the Left Channel PWB

5.3 Assembly of the Power Supply PWB

5.4 Chassis and Final Assembly

5.4.1Front Panel Components

5.4.2Back Panel Components

5.4.3Cable Clamps and Related Hardware

5.4.4Install Choke

5.4.5Install Printed Wiring Boards

5.4.6Install Transformers

5.4.7Install Remaining Chassis Components

5.4.8Cable Organization

5.4.9Connect Transformer Leads

5.4.9.1 Right Channel Output Transformer Primary Leads

5.4.9.2 Left Channel Output Transformer Primary Leads

5.4.9.3 Choke Leads

5.4.9.4 Power Transformer Primary Winding Leads

5.4.9.5 Power Transformer Secondary Leads

5.4.10Primary Power Connections

5.4.11Chassis-Mounted Controls

5.4.12PWB Interconnections

5.4.13Audio Cabling

5.4.14 Speaker PWB Assembly and Installation

5.4.15Output Transformer Secondary Connections

5.5 Final Assembly Check

Initial Checkout

Performance Measurement

7.1 IMD Measurement

101

7.2 Hum Balance Adjustment

7.5 Square Wave Performance

104

7.6 Bias Adjustment

106

7.7 Drive Balance Adjustment

108

7.8 Recorded Performance

109

Summary of Contents for 60 W Stereo Power Amplifier

Page 1: ...WhitakerAudio 60 W Stereo Power Amplifier User and Assembly Manual...

Page 2: ...itakerAudio Specifications subject to change without notice Any trademarks used in the manual are the property of their respective owners Note This document is intended to assist readers in building a...

Page 3: ...ation 60 5 4 9Connect Transformer Leads 63 5 4 9 1 Right Channel Output Transformer Primary Leads 63 5 4 9 2 Left Channel Output Transformer Primary Leads 64 5 4 9 3 Choke Leads 65 5 4 9 4 Power Trans...

Page 4: ...10Final Touches 111 8 Troubleshooting Guidelines 113 9 Safety Considerations 114 10 Notes and Tube Data 115 10 1Tube Characteristics 115 10 1 16U8A Pentode Triode Tube 115 10 1 27027A Beam Power Tube...

Page 5: ...of the signature series of products This amplifier shares the craftsmanship and impressive industrial design of the other offerings in the WhitakerAudio line This amplifier like the other products is...

Page 6: ...ay from the PWB and minimizes hum in the amplifier The PWBs are engineered to reduce off board connections thereby simplifying layout and providing for controlled characteristics from one unit to the...

Page 7: ...7 60 W Stereo Power Amplifier...

Page 8: ...ntrol As such the function of the volume control is only to set the nominal input level of the amplifier and would not typically be adjusted during use The plate and cathode outputs of the phase inver...

Page 9: ...4 5 6 8 2 7 5 6 8 2 7 1 4 3 4 5 6 1 9 8 3 2 7 R16 C6 16 Ohms 8 Ohms Speaker outputs T1 Ground 425 V dc B 40 V dc bias Ground Heater Heater 1 2 3 4 5 6 6 3 V ac to heaters R17 R18 C7 C8 C9 4 Ohms 400...

Page 10: ...alance 50 V tap D54 R59 C56 R61 Bias Adjust C57 20 60 V dc bias supply 7 R62 VR51 SW51 Power AC line input FL51 line filter Hot Neutral Ground PL51 pilot lamp RYL51 C59 VR52 CR51 ac ac R55 C58 Auxilia...

Page 11: ...e amplifier may not reach the full rated output power of 30 W per channel Power thermistor VR51 is used to limit current inrush upon application of ac line voltage to the transformers VR51 is rated fo...

Page 12: ...r level that might be advisable for the amplifier The range of adjustment is in the neighborhood of 20 to 60 V dc Test points are provided adjacent to R61 to simplify bias adjustment Exercise caution...

Page 13: ...not restricted by other devices shelving etc Because of the large number of interconnecting wires needed for this amplifier expanded sleeving is used where practical to organize the cabling This tends...

Page 14: ...ght Channel Built in California USA J C Whitaker 60 W Stereo Power Amplifier Neutrix NF2D 0 88 in 0 13 in Center Neutrix NF2D 0 88 in 0 13 in Center AC connector shell 0 75 in x 1 08 in Center 0 15 in...

Page 15: ...ll Dubilier 381LQ181M450K022 862 4752 C4 C5 0 22 F 600 V 4 Vishay 715P22456MD3 507 0335 C6 0 015 F 200 V 2 Vishay 715P15352JD3 70079360 C6a 82 pF 100 V padding 2 AVX SR151A820JAR 70195704 C8 C9 C60 0...

Page 16: ...4LAYSA101A 70153091 R61 5 k 2 W potentiometer 1 Honeywell Clarostat RV4LAYSA502A 753 1145 R62 2 7 k 2W 1 Ohmite OY272KE 296 2349 R64 10 1 1 Ohmite OX100KE 296 2246 RYL51 5 V dc relay contacts 240 V ac...

Page 17: ...r strip 3 Molex 38720 6204 607 0071 Main chassis 14 in x 17 in x 3 in steel 1 Hammond 1441 38BK3 806 1396 Main chassis baseplate 14 in x 17 in steel 1 Hammond 1431 38BK3 806 1426 Front panel 19 in x 3...

Page 18: ...ttelfuse 0313 500HXP 845 0307 Fuse block 1 Bussman S 8002 1 R 740 0772 PWB power supply 1 ExpressPCB Custom PWB amplifier blocks 2 ExpressPCB Custom PWB speaker terminals 2 ExpressPCB Custom Top chass...

Page 19: ...e sleeving medium 1 ft Expandable sleeving large 5 ft Heat shrink tubing small 5 ft Heat shrink tubing medium 2 ft Heat shrink tubing large 12 Spade terminal 6 screw 22 wire 11 Quick disconnect male 1...

Page 20: ...mmet 0 75 in mounting hole 8 Cable clamp 1 2 inch 8 Tie wrap small 10 ft Rosin core solder 8 Vinyl pads self adhesive 1 Paint semigloss black hammered 1 Paint black satin Table 2 2 Consumables for the...

Page 21: ...B Code Function Connection Color Code Component PL1 Output transformer plate 1 connection Blue T1 SC1 Output transformer screen 1 connection Blue yellow PL2 Output transformer plate 2 connection Brown...

Page 22: ...te Filament 4 from 300BX NC Not connected White red Filament 4 center tap from 300BX NC Not connected Red white Filament 4 from 300BX T52 6Vct 6 3 V center tap Green yellow from T52 T52 6Va 6 3 V ac G...

Page 23: ...igure 3 2 TERM5 6 3 V filament to amplifier boards Green TERM6 6 3 V filament to amplifier boards Green TERM7 Bias voltage output to amplifier boards White TERM8 Same as EXT FILa TERM9 Same as EXT FIL...

Page 24: ...24 WhitakerAudio Figure 3 1 PWB component layout a audio board b power supply board next page a...

Page 25: ...25 60 W Stereo Power Amplifier b...

Page 26: ...mers listed in this table may vary Consult device documentation before proceeding PWB Code Function Connection Color Code Notes GND Chassis ground T1com Output transformer secondary common Black 4ohm...

Page 27: ...esistors with an ohmmeter Capacitors can be checked with a capacitance measurement bridge While this is perhaps overkill it is instructive to see the variation in component values which measurement be...

Page 28: ...ectrolytic capacitors All audio cables of length greater than about 6 inches should use shielded cable Generally speaking the shield should be connected to ground at the load end Grounding both ends o...

Page 29: ...omponents be opened at a time as this will reduce the possibility of component mix ups Each section heading that follows marks a logical start stop point in construction of the amplifier Do not rush t...

Page 30: ...connect male tabs using the pads provided on the board There are 11 positions in all Solder in place Note that the mounting pins fit tight into the board This is normal Use a pair of pliers to hold th...

Page 31: ...R10 22 k 0 5 W Solder in place Install R11 2 2 k 2 W Solder in place providing about inch clearance above the board Install R12 and R13 100 k 0 5 W Solder in place Figure 5 1 Recommended procedure fo...

Page 32: ...ide of the mounting pad Be careful to not use too much heat as that may damage the capacitor After soldering the capacitors in place double check your work Note that the negative terminals all face th...

Page 33: ...n 1 on the PWB is identified by a square pad Prior to mounting the octal sockets V2 and V3 bend pins 2 and 7 the heater connections outward away from the center of the socket This will facilitate conn...

Page 34: ...7 the heater terminals and solder 2 Cut the wires in descending length from pin 1 to pin 8 3 Properly orient the socket with respect to the PWB and insert the wires into their respective pads 4 After...

Page 35: ...so it is not near the soldering point If the heat shrink tubing gets hot it will be very difficult to slide into position later Crimp the other wire on pin 5 of V1 Solder in place keeping in mind the...

Page 36: ...hrough the heat shrink tubing on the lead already connected to pin 7 of V3 Route the wire to the pin and crimp in place Solder keeping the heat shrink tubing away from the hot wires and the soldering...

Page 37: ...gainst the PWB Trim the wire lengths as needed to comfortably reach the pads on the foil side of the board Insert one wire in the TERM5 position and solder in place Solder from the foil side of the bo...

Page 38: ...38 WhitakerAudio connections or solder splash that might cause a short circuit Set the right channel amplifier board aside it will be used later Figure 5 3 b...

Page 39: ...ck disconnect male tabs using the pads provided on the board There are 11 positions in all Solder in place Note that the mounting pins fit tight into the board This is normal Use a pair of pliers to h...

Page 40: ...be installed later Install R17 and R18 100 k 2W Solder in place providing about inch clearance above the board Clean the soldering iron tip Install C1 25 F 50 V electrolytic Solder in place observing...

Page 41: ...the corner of the PWB closest to the XFMRCT tab The ground lug goes on the component side of the board The screws should be finger tight for now In the following steps the tube sockets will be mounted...

Page 42: ...starting at pin 1 on one side of the socket and on pin 9 on the other side Note The lead lengths for the octal tube sockets vary from one vendor to another The procedure described above works well for...

Page 43: ...of 22 green heater wire Place one piece of 1 2 inch long heat shrink tubing over one end of each wire Crimp one wire on pin 4 of V1 Solder in place When soldering make sure the heat shrink tubing is...

Page 44: ...e too much heat Twist the wires together and route to socket V2 see Figure 5 2d for placement The wires should be placed at socket level Do not dress the wires against the PWB Trim the wire lengths as...

Page 45: ...oard Insert the other wire in the TERM6 position and solder in place Assembly of the left channel PWB has now been completed The finished board is shown in Figure 5 3 The left and right channel PWBs a...

Page 46: ...board There are 59 positions on the power supply board Solder in place Note that the mounting pins fit tight into the board This is normal Use a pair of pliers to hold the tab while inserting the pins...

Page 47: ...he foil side of the mounting pad Be careful to not use too much heat as that may damage the capacitor After soldering the capacitors in place double check your work Note that the negative terminals al...

Page 48: ...he four terminal Molex barrier strip Solder in place Find tube V51 and set it aside in a safe place The tubes will be installed during the final checkout process Examine the fuse holder Some devices h...

Page 49: ...cket the side the tube plugs into should face outward Loosely tighten the mounting screws See Figure 5 2a Install connecting wires from the PWB pads to the tube socket pins Solder in place Materials f...

Page 50: ...50 WhitakerAudio Figure 5 4 Completed power supply PWB a component side b next page foil side a...

Page 51: ...51 60 W Stereo Power Amplifier Figure 5 4 b...

Page 52: ...s divided into a number of sub sections allowing the builder to proceed at a measured pace A full size image of the completed chassis bottom view is also provided in Figure 5 5 Refer to this image as...

Page 53: ...d 1650HA 0 188 in Qualtek RFI Filter Cable clamp and Plexiglas cover post Cable clamp Cable clamp and Plexiglas cover post Cable clamp and Plexiglas cover post Cable clamp Cable clamp and Plexiglas co...

Page 54: ...rew terminal should face downward toward the chassis bottom plate Using caution to not scratch the finish tighten the right and left channel volume control mounting nuts Be certain that the terminals...

Page 55: ...e chassis so they can be used individually Tighten the lock tight nut Install two flat washers on the screw and then the wing nut Tighten the wing nut finger tight The finished installation is shown i...

Page 56: ...ntified as Plexiglas cover mounting posts Find the cable clamp hardware package There are eight sets in this package Install the cable clamps using the 6 hardware provided for the single purpose cable...

Page 57: ...present Set these in a convenient place Check the heater wiring on the foil side of the board Position so the wiring will rest against the chassis when secured in place Carefully place the right chan...

Page 58: ...h the chassis along with the transformer leads The speaker leads yellow green white black should face to the rear of the chassis Locate left channel output the output transformer T1 Install using the...

Page 59: ...l to not scratch the top side finish when tightening the nut Once the device has been mounted place the potentiometer in the approximate center position using a common blade screwdriver The smaller di...

Page 60: ...ng a pair of pliers bend the tab down to the base of the potentiometer Place the lock washer provided on the shaft and insert the device through the mounting hole Note that R20 is located adjacent to...

Page 61: ...ng onto the primary leads of the left channel output transformer T1 Position one end of the sleeving near the base of the transformer where the leads enter the chassis Stretch the sleeving to its full...

Page 62: ...one 4 inch piece of medium sized sleeving onto the smaller bundle of secondary leads from the plate transformer T51 Be sure to include the black ground wire from the transformer case Position one end...

Page 63: ...will comfortably reach their respective terminals Note that the sleeving containing the primary leads from T1 will rest against the bottom chassis plate Use the red terminal connectors After each ter...

Page 64: ...end of the wire Attach to the PL1 post on the left channel PWB Connect SC1 output transformer screen 1 connection Find the blue yellow wire from the left channel output transformer Install a connecto...

Page 65: ...s The following steps assume a line input voltage of 120 V ac Trim the lead lengths so the wires will comfortably reach their respective terminals Use the red terminal connectors After each terminal i...

Page 66: ...r respective terminals Use the red terminal connectors unless otherwise stated After each terminal is attached to a lead gently pull on the wire and terminal to make sure a good crimp has been made Co...

Page 67: ...ne of the yellow leads from the power transformer Install a connector to the wire Attach to the 5VH2a post on the power supply PWB Connect 5VH2b 5 V 3A heater Find the other yellow lead from the power...

Page 68: ...ch the other end of the black wire to the lower terminal closest to the chassis of circuit breaker CB1 Using the primary ac wire included in the AC Power Connector Hardware package prepare a 14 inch p...

Page 69: ...nose pliers to secure the connector Find the white 16 wire from circuit breaker CB1 Connect to the line terminal on the input side of ac line filter FL51 that is closest to the back panel of the chas...

Page 70: ...te wire Attach a quick disconnect terminal to one end of the wire Attach to the ACH 7 AC hot to PL1 post on the power supply PWB Route the other end of the wire toward the front panel The two 22 white...

Page 71: ...nel power switch SW51 Secure the other spade terminal to one of the outside terminals on SW51 Note tighten the unused screw on SW51 to ensure it does become loose over time Prepare one 6 inch long 16...

Page 72: ...Terminal numbering for the chassis mounted potentiometers is shown in Figure 5 9 Prepare two 19 inch long 22 green wires Install quick disconnect connectors on one end of each wire Place the connecto...

Page 73: ...needed Secure to the low terminal of R61 terminal 1 Solder in place Prepare one 20 inch 22 red wire Install a quick disconnect connector on one end Route the wire through the cable clamp adjacent to...

Page 74: ...ne 15 inch 22 yellow wire Install a quick disconnect connector on one end Attach to the R20arm post on the left channel PWB Loosly twist this wire along the length of the yellow wire just installed Ro...

Page 75: ...ed the loose end of the wire through the expandable sleeving The end with the spade terminal should be grouped with the quick disconnect terminals on the green wire pair Prepare a 17 inch long 22 blac...

Page 76: ...d the loose end of the wire through the expandable sleeving The end with the spade terminal should be grouped with the quick disconnect terminals on the green wire pair Prepare a 15 inch long 22 white...

Page 77: ...green wires from the two amplifier PWBs Combine into a single quick disconnect terminal and crimp 2 wires Double check to make sure you have one wire from each PWB Find the other 18 green wires from t...

Page 78: ...e place a short approximately 3 4 inch long piece of heat shrink tubing on each end of the audio cable For the end of the cable inserted into the Molex connector process apply heat after the wires hav...

Page 79: ...h connector pins to each of the two wires on one end of the audio cable Insert the connector pins into the socket housing as follows shield to position 1 and white to position 2 Cut two short pieces o...

Page 80: ...ert the Molex socket into the Conn1 connector on the left channel PWB Note that the drain wire goes to the first GND position Route the cable to the rear of the chassis using the cable clamps along th...

Page 81: ...to the center pin Solder the shield wire to the ground shell end Dress the cable to rest against the chassis The audio input and feedback circuit connections have now been made Double check your work...

Page 82: ...evice near the component body Solder and trim the leads Install C6 0 015 F on the right channel speaker PWB in the position Cfb Solder in place Install C6 0 015 F on the left channel speaker PWB in th...

Page 83: ...h other wiring in the chassis Cut a 4 inch long 18 yellow wire Attach a quick disconnect terminal to one end of the wire Using a pair of long nose pliers fashion a small loop at the other end of the w...

Page 84: ...peaker terminal PWBs support the board as needed to avoid stressing the PWB Attach a quick disconnect terminal to the free end of the 8 inch 18 black wire Attach to one of the GND posts on the right c...

Page 85: ...right channel output transformer Connect the terminal to the T1com post on the right channel speaker PWB Find the green 4 lead from the right channel output transformer Connect the terminal to the 4oh...

Page 86: ...ctions are made on either the right or left channel speaker PWBs for the following terminals HEAD 1 HEAD 2 or LOAD 5 5 Final Assembly Check The 60 W stereo amplifier has now been completed Make a thor...

Page 87: ...87 60 W Stereo Power Amplifier Figure 5 11 Bottom view of completed amplifier...

Page 88: ...88 WhitakerAudio Figure 5 12 Detail views of the 60 W stereo amplifier a speaker terminal PWB b left channel amplifier PWB c power supply PWB d right channel amplifier PWB a b d c...

Page 89: ...tance between the line terminals of the ac cord It should be a high value with the front panel power switch Off due to VR3 typically greater than 300 k and approximately 6 when the power switch is On...

Page 90: ...es Removed Tube Pin No Typical Reading Notes V1 6U8A 1 50 k Varies due to filter capacitors in circuit 2 10 k to 100 k Varies with setting of volume control 3 196 k Varies due to filter capacitor in c...

Page 91: ...present Be extremely careful As a safety measure do not work alone Do not let the amplifier run unattended until all preliminary tests have been successfully completed 12 Attach the ac power connecto...

Page 92: ...6 should be approximately 40 V dc 19 Check operation of the Bias Adjust potentiometer R61 Measure the voltage at one of the output tube control grids as detailed in the previous step and vary the posi...

Page 93: ...measured Next measure the voltage between ground and pin 6 of V51 A value of approximately 400 V ac should be measured Note do not measure the plate voltage between pins 4 and 6 as the potential diffe...

Page 94: ...measured with respect to ground using a high impedance voltmeter Variations within 10 percent are typical with an ac input voltage of 120 V ac These measurements can be taken from the top of the chass...

Page 95: ...tion or motorboating is observed immediately remove power from the unit It is important that an oscilloscope be connected to the output terminals in addition to a speaker and perhaps other test equipm...

Page 96: ...d the amplifier should draw about 1 25 A from the line If problems are experienced disconnect power and recheck the installation of all components particularly the input stage V1 of the amplifiers 44...

Page 97: ...barrier strip is typically 425 V 47 For the performance tests detailed in the next section set the bias as follows While monitoring terminal 2 of the right or left channel PWB barrier strip set the B...

Page 98: ...unit run for about 10 minutes Then disconnect all power from the amplifier remove the wall plug and check the B output of the power supply PWB Terminal 1 or 2 to ensure the supply voltage has discharg...

Page 99: ...eckout steps detailed in Section 6 However if the test equipment is available it is recommended that measurements be taken at various power output levels e g 1 W 5 W 10 W 15 W 20 W 25 W and 30 W Measu...

Page 100: ...V rms Volume control fully clockwise Frequency response 1 dB 15 Hz to 30 kHz THD 0 8 Note 1 IMD at 8 9 V rms output 1 1 Note 2 Noise unweighted shorted input terminals 87 dB Measurements taken at 20 W...

Page 101: ...value of that signal but the altered relationship between the average and rms values will cause a discrepancy in the indication Such discrepancies are generally not large however the difference in pea...

Page 102: ...nt of travel While this adjustment can be done with a digital display an analog meter typically provides for easier reading Carefully adjust the Hum Balance control for minimum signal level A typical...

Page 103: ...2 V rms With 0 92 V rms input and an ac line voltage of 120 V an output of approximately 15 5 V rms should be observed at the output speaker terminals which translates to 30 0 W output In order to kee...

Page 104: ...15 W and 30 W3 Measurements of the right channel and left channel should be essentially identical The following comments and observations can be made 2 W power output a Tilt is observed at 100 Hz b A...

Page 105: ...e in program material or connecting or disconnecting an input while the power is on A key consideration in preventing overload problems is to ensure that the amplifier when over driven clips symmetric...

Page 106: ...Adjustment The bias setting for the amplifier is critical to proper operation and long term reliability The recommended bias setting of 40 V has been found to be a good operating point for this amplif...

Page 107: ...he two settings Repeat the process for the left channel The optimal points between channels should roughly coincide Note that some compromises may be necessary to provide for the best relative perform...

Page 108: ...rmance possible from the amplifier There are two ways of adjusting drive voltage balance one requires an oscilloscope and the other requires a distortion analyzer Use the following procedure Connect a...

Page 109: ...is recommended that the bias adjustment steps outlined previously be repeated after the drive balance procedure 7 8 Recorded Performance It is recommended that the performance of each channel be reco...

Page 110: ...re typically given a rating based on measured performance e g a rating of 18 A tube set with a different rating such as 22 may perform identically in all respects except maximum power output where the...

Page 111: ...anual test equipment during which time the typical heating pattern for this unit can be observed It will be noted that the output transformers run at essentially room temperature The power transformer...

Page 112: ...tions for normal operation An Automatic Protection Option is available for this amplifier that provides additional operational safeguards including 1 automatic shutdown after a specified period of tim...

Page 113: ...fail without a reason Try and piece together the sequence of events that led to the problem Then the cause of the failure not just the more obvious symptoms will be corrected In high voltage power su...

Page 114: ...or other protective eye wear when building or working on electronic equipment Injuries can result from solder splashes cleaning chemicals and other unexpected events When trimming the leads of a comp...

Page 115: ...hase splitter circuits the pentode unit should drive the triode unit Selected tube parameters are listed in Table 10 1 Table 10 1 Key Parameters of the 6U8A General Characteristics Heater ac dc 6 3 V...

Page 116: ...volt age to be used When a voltage dropping resistor is used the minimum value of resistor that will assure tube Triode cathode to heater 3 pF Pentode cathode pentode grid 2 internal shield 3 pF Pento...

Page 117: ...o equipment The pinout of the 8 contact socket is given in Figure 10 3 This tube like other power handling devices should be adequately ventilated Operating characteristics are charted in Figure 10 4...

Page 118: ...de heater grid 2 grid 3 7 5 pF Class AB1 Amplifier Maximum Ratings Design Maximum Values Plate voltage 600 V Grid 2 screen grid voltage 500 V Plate dissipation 35 W Grid 2 screen grid input 5 W Push P...

Page 119: ...1 to grid 1 voltage 68 V Zero signal cathode current 134 mA Maximum signal cathode current 155 mA Effective load resistance plate to plate 8000 Maximum signal output 24 W Note 1 Obtained from taps on...

Page 120: ...pply voltage 900 V rms Filter input capacitor 40 F Total effective plate supply impedance per plate 67 ohms DC output voltage at input to filter approx at specified load current 137 5 mA 520 V 275 mA...

Page 121: ...121 60 W Stereo Power Amplifier...

Page 122: ...WhitakerAudio 60 W Stereo Power Amplifier...

Page 123: ...and device type For example all 1 k 1 2 watt resistors for the right channel PWB are packaged together Each group of parts is placed in a resealable clasp type envelope with a self adhesive label appl...

Page 124: ...h threaded 4 standoff quantity 6 right channel R4 825 0 5 W right channel R17 R18 100 k 2W 1 2 inch threaded 4 standoff quantity 4 right channel 4 terminal Molex barrier strip right channel 4 term Mol...

Page 125: ...lex housing quantity 2 left channel C10 10 pF 500 V ceramic left channel R1 1 m 0 5 W left channel C10 0 01 F 100 V ceramic left channel R20 2 5 k potentiometer left channel Table 3 Power Supply Compo...

Page 126: ...is Chassis feet quantity 6 chassis R60 100 2W potentiometer chassis FL51 AC line filter chassis Large knob quantity 2 chassis R61 25 k 2 W potentiometer chassis RYL51 5 V dc relay contacts 240 V ac 30...

Page 127: ...hassis Ground lug hardware chassis Plexiglas trim chassis Front panel 19 in x 3 5 in chassis Speaker PWB layout chassis Top chassis decal chassis Plexiglas trim hardware chassis Cable clamp hardware c...

Page 128: ...128 WhitakerAudio...

Page 129: ...n the preferred method of cutting the tubing is to use a so called heat knife If such a tool is unavailable scissors may be used Examine the connector body The pin numbers are stamped on both sides of...

Page 130: ...two white wires together Loosely twist the two green wires together Cut a 3 ft length of expandable sleeving and place over the cable bundle Cut two 3 4 inch long pieces of heat shrink tubing and plac...

Page 131: ...wire to pin 5 Green wire to pin 6 Black wire to pin 9 Note that pin 7 and pin 8 are not used Process heat the tubing closest to the connector socket Caution do not use too much heat as it can melt the...

Page 132: ......

Page 133: ...temperature component damage or shortened tube life could result This feature shuts down the amplifier if the temperature inside the chassis exceeds 170 F This is well below the maximum rated operatin...

Page 134: ...The protection architecture will keep the amplifier in the off state until the input ac power is cycled by operating the front panel power switch off and then on Varistors are included across the 120...

Page 135: ...131 Automatic Protection Option 40 60W Version Figure 1 Automatic protection option schematic diagram for the 40 W amplifier...

Page 136: ...beyond that The voltage sensing circuits Q204 Q205 and Q206 Q207 are identical The values of R214 R215 and R218 R219 are determined by the operating voltage being measured As a general guideline R214...

Page 137: ...k 0 5 W 1 Vishay RN65D4023FB 14 70200375 R205 33 0 5 W 1 Ohmite OL3305E 70023830 R207 1 k 2 W 1 Ohmite ON1025E 70022958 R208 1 k 0 5 W 1 Ohmite OL1025E 70022919 R209 2 m PC mount potentiometer 1 Bourn...

Page 138: ...disconnect female red 12 3M FDI18 250Q 70233873 3 8 inch threaded 4 standoff 5 Keystone Electronics 2202 70181889 Printed wiring board 1 ExpressPCB custom SW201 Pushbutton switch 1 NKK Switches SB401...

Page 139: ...avail ACneutral AC power neutral White LoadN Amplifier load neutral White AChot AC power hot Black Switch1 Front panel power switch Black Switch2 Front panel power switch Black LoadH Amplifier load ho...

Page 140: ...roduct from WhitakerAudio as a ready to assemble package For builders that have acquired the components on their own and are using the manual as an assembly guide it is recommended that the parts be d...

Page 141: ...137 Automatic Protection Option 40 60W Version b...

Page 142: ...F 25 V electrolytic Auto Off R201 8 2 m 0 5 W Auto Off R213 R217 470 0 5 W Auto Off C202 1000 pF 100 V Auto Off R202 15 m 0 5 W Auto Off R214 R215 R218 R219 180 k 0 5 W Auto Off C203 0 047 F 100 V Au...

Page 143: ...om and light The following tools are minimally required for assembly Common screwdriver Phillips screwdriver Wire cutters Pliers Long noise pliers Solderless terminal crimp tool 25 35 W soldering iron...

Page 144: ...r in place Note that the mounting pins fit tight into the board This is normal Use a pair of pliers to hold the tab while inserting the pins into the PWB Make sure the PWB is resting on a soft flat su...

Page 145: ...s denoted by the square mounting pad Install C202 1000 pF 100 V Solder in place Install C203 0 047 F 100 V Solder in place Install C204 C205 C207 1 000 F 50 V electrolytic Solder in place observing pr...

Page 146: ...03 Q208 C9F NTE5408 Solder in place Be certain to properly align the leads of the device Install Q204 Q206 2N406 NTE102A Solder in place Be certain to properly align the leads of the device Install Q2...

Page 147: ...nent Finally tighten the mounting screw Find the 0 5 A fuse Install in the socket Install the power transformer Transformer PC mount 120 V ac primary 25 V ac secondary Orient the device so pin 1 lines...

Page 148: ...amage the right channel PWB The location of the switches is not critical however it is recommended that the toggle switch be placed toward the upper deck of the chassis with the push button below it A...

Page 149: ...a pin to one end of each wire Insert a wire pin into position 3 on the connector Insert the other wire pin into position 4 on the connector Loosely twist the wires together Prepare two 23 inch long 22...

Page 150: ...e terminal to the wire Attach to Terminal 1 on the right channel PWB Prepare a 10 inch long 22 high voltage 600 V red wire Attach a quick disconnect terminal to one end and a spade terminal to the oth...

Page 151: ...tside posts Prepare a 14 inch long 16 black wire Attach quick disconnect terminals on each end Attach one end to the ACH 1 terminal on the power supply PWB Attach the other end to the LoadH terminal o...

Page 152: ...03 Voltage sense 1 RYL205 Voltage sense 2 RYL206 Carefully measure the V voltage this can be done at the anode of D203 A reading of 25 V dc should be observed Carefully measure the ac voltage at the A...

Page 153: ...149 Automatic Protection Option 40 60W Version Figure 4 Automatic Protection Option installed in the 40 W Stereo Amplifier...

Page 154: ...150 WhitakerAudio...

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