TABLE OF CONTENTS Specifications_____________________________________________________________ 1 Table of Contents__________________________________________________________ 2 ‐ 3 Front Panel Controls________________________________________________________ 4 ‐ 5 Rear Panel Connections_____________________________________________________ 6 ‐ 9 Safety Instructions_________________________________________________________ 10 ‐ 12 Exploded Diagram__________________________________________________________ 13 Parts Table________________________________________________________________ 14 Front Panel PCB ‐ Schematic__________________________________________________ 15 Front Panel PCB – Bill of Materials_____________________________________________ 16 Front Panel PCB – Layout_____________________________________________________17 Speaker PCB – Schematic_____________________________________________________18 ‐ 19 Speaker PCB – Bill of Materials________________________________________________ 20 Speaker PCB – Layout________________________________________________________21 Input PCB – Schematic_______________________________________________________22 Input PCB – Bill of Materials___________________________________________________23 ‐ 24 Input PCB – Layout__________________________________________________________25 Preamp PCB – Schematic____________________________________________________ 26 ‐ 28 Preamp PCB – Bill of Materials________________________________________________ 29 ‐ 30 Preamp PCB – Layout_______________________________________________________ 31 Volume PCB – Schematic_____________________________________________________32 Volume PCB – Bill of Materials________________________________________________ 33 Volume PCB – Layout________________________________________________________34 Power Amp PCB ‐ Schematic__________________________________________________35 ‐ 39 Power Amp PCB – Bill of Materials (550A)_______________________________________40 ‐ 41 Power Amp PCB – Bill of Materials (650A)_______________________________________42 ‐ 43 Power Amp PCB ‐ Layout____________________________________________________ 44 Mains PCB (EU 230V) – Schematic_____________________________________________ 45 ...
Page 3
Mains PCB (EU 230V) – Bill of Materials___________________________________________46 Mains PCB (115V) – Schematic__________________________________________________47 Mains PCB (115V) – Bill of Materials_____________________________________________ 48 Mains PCB (115V) – Layout_____________________________________________________49 Protection PCB – Schematic____________________________________________________ 50 Protection PCB – Bill of Materials________________________________________________ 51 Protection PCB – Layout________________________________________________________52 Set‐up Procedure_____________________________________________________________ 53 IC Details____________________________________________________________________ 54 ‐ 61 ...
Page 4
Cambridge Audio 550A & 650A Front panel connections 1. Standby/On Switches the unit between Standby mode (indicated by dim power LED) and On (indicated by bright power LED). Standby is an eco power mode where the power consumption is less than one watt. The unit is designed so that it can be left safely in Standby mode when not in use.
Page 5
Cambridge Audio 550A & 650A affect the Tape Out connections. It is advisable to turn the Volume control fully anti-clockwise before switching the amplifier on. 9. Balance This control allows you to adjust the relative output levels of the left and right channels. In the central position the output from each channel is equal.
Loop out for control bus commands to another unit. 6. Pre-Out Connect these sockets to the inputs on an external power amplifier(s), such as Cambridge Audio’s 840W model, or an active subwoofer, etc. 7. Tape In...
Page 7
Tape In sockets. The Tape Input circuit of the 550A/650A is a ‘monitor’ type, different from the other five inputs. For the five normal inputs, the source selected for listening to will also be sent out of the Rec 1/Rec 2 outputs for recording.
Page 8
Cambridge Audio 550A & 650A Tape connection The diagram below shows how to connect the amplifier to a tape recorder or other source with a record and monitor connection. Please note that either of the tape loop outputs can be used (as they are both the same signal in parallel).
Page 9
Cambridge Audio 550A & 650A Pre-Out connections The Pre-Out sockets are for connecting to the input sockets of a power amplifier, such as Cambridge Audio’s 840W model, or active subwoofer. The diagram below shows how to connect the amplifier to an active subwoofer via the Line In inputs on the subwoofer.
Cambridge Audio 550A & 650A Important safety instructions For your own safety please read the following important safety instructions carefully before attempting to connect this unit to the mains power supply. They will also enable you to get the best performance from and prolong the life of the unit: 1.
Page 11
This product complies with European Low Voltage (2006/95/EC) and Electromagnetic Compatibility (89/336/EEC) Directives when used and installed according to this instruction manual. For continued compliance only Cambridge Audio accessories should be used with this product and servicing must be referred to qualified service personnel. C-Tick mark This product meets the Australian Communications Authority’s Radio communications and EMC...
Page 12
Cambridge Audio 550A & 650A Electronic audio components have a running in period of around a week (if used several hours per day). This will allow the new components to settle down and the sonic properties will improve over this time. Power sources The unit should be operated only from the type of power source indicated on the marking label.
Page 16
550A/650A Front Panel PCB BOM Factory Part Value Description/Type Component Ident ManPN Tolerance PackageInfo AP Part Number Number RESISTORS 1/4W Metal Film R5, R6 10mm Pitch 220R 1/4W Metal Film R7-R12, R14 10mm Pitch 1/4W Metal Film R4, R13 10mm Pitch...
Page 20
550A 650A Speaker PCB BOM Factory Part Value Description/Type Component Ident ManPN Tolerance PackageInfo AP Part Number Number RESISTORS 1/4W Metal Film 10mm Pitch 1/8W Metal Film 7.5mm Pitch 1/2W Carbon R1, R2 12mm Pitch 1/4W Metal Film 10mm Pitch...
Cambridge Audio 550A & 650A -15V Met. Polyester 47nF 63V RC4580P 10nF 50V CN11:A U6:A Audio Op Amp Ceramic U12:A 47nF 63V PreOut Right LK48 LK52 Met. Polyester 10pF 50V LK22 1/8W Metal Film TM R CN10:C AV2-8.4-9 NE5532P 24 AWG...
Page 23
550A 650A Input PCB BOM Factory Part Value Description/Type Component Ident ManPN Tolerance PackageInfo AP Part Number Number RESISTORS 100R 1/4W Metal Film R5, R16, R17 10mm Pitch 220R 1/4W Metal Film 10mm Pitch 220R 2W Carbon 20mm Pitch Raise off PCB...
Cambridge Audio 550A & 650A 2P2T SW1:B Pushbutton Switch VR2:A R POut RCh Out NP Electrolytic 1/4W Metal Film 47uF 16V 150k Balance Pot LK30 1/4W Metal Film 24 AWG 10mm Pitch Amp GND 100nF 100V 1/4W Metal Film 6 Way...
Page 27
Cambridge Audio 550A & 650A -15V Tone -15V Tone U3:B Black Cable Tie NE5532P Tie cables AP23887/# and AP23910/# together RL1:C Audio Op Amp LK37 RCh HP Out R POut 24 AWG 10mm Pitch NP Electrolytic LK36 ME2-5S Black Cable Tie...
Page 28
Cambridge Audio 550A & 650A LK50 24 AWG 1/4W Metal Film 1/4W Metal Film +15V Tone +5V Protect 10mm Pitch -15V Tone CN12 2X5 Way +5V D 1/8W Metal Film DIL Male Header LK48 Clock Data 24 AWG DGND LK49...
Page 29
550A 650A Preamp PCB BOM Factory Part Value Description/Type Component Ident ManPN Tolerance PackageInfo AP Part Number Number RESISTORS 1/4W Metal Film 10mm Pitch 1/4W Metal Film R14, R15 10mm Pitch 1/8W Metal Film R38, R49 7.5mm Pitch 1/4W Metal Film...
Page 33
550A 650A Volume PCB BOM Factory Part Value Description/Type Component Ident ManPN Tolerance PackageInfo AP Part Number Number RESISTORS 1/8W Metal Film R3, R18 7.5mm Pitch 1/8W Metal Film R9, R12 7.5mm Pitch 1/8W Metal Film R7, R13 7.5mm Pitch 1/8W Metal Film 7.5mm Pitch...
+45V L 2 +45V L Cambridge Audio 550A & 650A 2SC2240GR R126 NPN Low Noise 1/8W Metal Film R105 10uF 63V 220uF 63V 47nF 63V 150R 150R 1N4148 Electrolytic Electrolytic Met. Polyester Signal Diode R104 R101 MPSA92 100k MPSA92 PNP Signal...
Page 36
Cambridge Audio 550A & 650A +45V R 2 +45V R 2SC2240GR R128 NPN Low Noise 1/8W Metal Film 10uF 63V 220uF 63V 47nF 63V 150R 150R 1N4148 Electrolytic Electrolytic Met. Polyester Signal Diode R120 R124 MPSA92 100k MPSA92 PNP Signal...
Page 37
Cambridge Audio 550A & 650A 650A Only Test Points No Stuff Fast Blow Fuse No Stuff No Stuff No Stuff No Stuff Rectifier Rectifier No Stuff Mono Ceramic Met Polyester Straight Header +45V L PSU +45V R PSU No Stuff...
Page 38
Cambridge Audio 550A & 650A LK107 Clip FB L Tinned Link Wire Tinned Link Wire 24AWG 24AWG 1/8W Metal Film Tinned Link Wire 24AWG Clip In L Tinned Link Wire LK123 24AWG 1/8W Metal Film PIC Clip Detect +45V R...
Page 40
550A Power Amp PCB BOM Factory Part Value Description/Type Component Ident ManPN Tolerance PackageInfo AP Part Number Number RESISTORS R27, R65, R78, 0.22R 3W Wirewound 20mm Pitch 1072-208330E000 Raise off PCB R113 3W WireWound R28, R66 20mm Pitch 1074-707330E000 Raise off PCB...
Page 45
Cambridge Audio 550A & 650A " ! "7 0 ! "7 0 ""( B B D & 8B B ""( B B D & 8B B "7 0 "7 0 ,C 8@ "(( ,C 8@ "(( "% " " " #((# <...
Page 46
550A 650A EU 230V Mains PCB BOM Value Description/Type Component Ident ManPN Tolerance PackageInfo Factory Part Numer AP Part Number RESISTORS 1/8W Metal Film 7.5mm Pitch 1/8W Metal Film 7.5mm Pitch CAPACITORS 1nF 400V X1/Y1 Mains Rated C1, C2 CCDE102MBV09 9.5mm Pitch...
Page 47
Cambridge Audio 550A & 650A " ! "7 0 ! "7 0 ""( B B D & 8B B ""( B B D & 8B B "7 0 "7 0 ,C 8@ "(( ,C 8@ "(( "% " " " #((# <...
Page 48
550A 650A Mains CU 115V PCB BOM Value Description/Type Component Ident Manufacturer ManPN Tolerance PackageInfo Yanion P/N NOTES RESISTORS 1/8W Metal Film 7.5mm Pitch 1/8W Metal Film 7.5mm Pitch CAPACITORS C & C 1nF 400V X1/Y1 Mains Rated C1, C2 CCDE102MBV09 9.5mm Pitch...
Cambridge Audio 550A & 650A Set‐up Procedure When replacing the STD03NY and STD03PY (U1 – U4) output devices, adjust PR1/PR2 to achieve 13mV (+/‐ 1mV) DC with no signal applied, measured across each of the 0.22R emitter resistors. ...