Trace-Elliot Velocette SE Service Manual 电路图.pdf

TRACE ELLIOT SERVICE MANUAL NO. SM00026 ISSUE 1 Date:April 9th 1998 Product Code :T3460 Model No :Velocette SE Technical File No :TE000026 Issued by: Trace Elliot Limited. Blackwater Trading Estate The Causeway, Maldon Essex CM9 4GG. RadioFans.CN 收音机爱 好者资料库 1 PARTS LIST FOR VELOCETTE SE PCB ISSUE 1 13/12/96 PS DescriptionPart CodeQtyWhere Used PCBPC00066 issue 11 RESISTORS 0 ohm link72-RCZERO7R1 (8 OHM) and where shown on PCB 1K5 1/4W72-RM1K54R10 R14 R15 R22 10K 1/4W72-RM10K2R30 R31 10K 1W72-RM10K-1WATT2R27 R28 27K 1/4W72-RM27K1R5 68K 1/4W72-RM68K3R8R9R13 100K 1/4W72-RM100K1R4 100K 1W72-RM100K-1WATT3R11 R23 R24 180K 1/4W72-RM180K1R16 220K 1W72-RM220K-1WATT3R21 R29 R33 470K 1/4W72-RM470K3R3R6R32 1M0 1/4W72-RM1M3R2R12 R17 390R 6W72-RWW390R-6W1R26 1K0 6W72-RWW1K-6W1R18 3K3 4W72-RWW3K3-4W1R25 SEMICONDUCTORS 1N400772-D-IN40074D1D2D3D4 CAPACITORS 2n2100V axial72-C2N2-100VCA1C10 100n100V axial72-C100N-100VCA3C9C26 C27 100p 1KV ceramic72-C100P-1KVCD1C11 150p 100V ceramic72-C150P-100VCD1C2 220p 1KV ceramic72-C220P-1KVCD1C1 470p 1KV ceramic72-C470P-1KVCD1C3 1n0 1KV ceramic72-C1000P-1KVCD2C16 C17 4n7 1KV ceramic72-C4700P-1KVCD4C18 C19 C24 C25 22n 400V poly box72-C22N-400VP4C4C5C8C12 100n 250V poly box72-C100N-250VP1C6 1u5 35V tant72-C1.5-35VT2C7C13 2u2 35V tant72-C2.2-35VT1C15 22u 450V elect rad72-C22-450VER2C20 C21 47u 450V elect rad72-CAP-47450V1C22 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 2 220u 35V elect rad72-C220-35VER1C14 330u 250V elect rad72-CAP-330250V2C23 C28 CONNECTORS 3way 0.1”72-HEAD-3W-24HTR1 HTR2 HTR3 HTR4 CRIMP CONNECTORS72-CRIMP-PCB-TAB12TX1 - 10LS1 (x2) TEST PIN73-PIN-TERM3TP0 TP1 TP2 SOCKETS 1/4” MONO JACK SKT73-SKT-JCKBNBG3SK1 SK2 SK3 SWITCHES Mini Toggle SPDT vert73-SWT-M-TGL-PCB1SW1 POTENTIOMETERS 1M073-POT-A1M1RV1 250K LIN DUAL GANG73-POT-B250K-DG1RV2 FUSE HOLDERS Fuse holder PCB 1.25”72-FUS-HLD-PCB-22FS1 FS2 VALVE BASES B9A PCB valve base73-VAL-SOCKET2V1V2 Octal PCB valve base73-VAL-SOCKET-21V3 FLYING LEAD Cathode heater leadC00-LEAD-VSE-HTR1to be inserted into HTR1, HTR2, HTR3 & HTR4 13 December 1996 Paul Stevens 1 VELOCETTE SE CIRCUIT DISCRIPTION Please refer to circuit diagram for DC voltages and other information INPUT SECTION SK1 and SK2 are the HI and LO sensitivity inputs respectively. When the LO socket is used R8, R9 and R17 act as a potential divider to reduce the input level to the preamp. C10 has two purposes, firstly to block any DC from the input that may unintentionally be present, this would otherwise change the bias point of the first valve stage, secondly the value of the capacitor has been chosen so that there is a slight roll off of lower frequencies, this prevents the sound from getting too muddy. PREAMP V1a is the first gain stage and is configured as a cathode bias, common cathode, voltage amplifier with bypassed cathode resistor for increased gain. C11 has been added for high frequency stability. R3 and C3 give a slight presence lift and the frequency of the Bright effect is set by C2, which, when switched in, is across pins 2 and 3 of RV1 (Volume). Obviously connected like this the amount of brightness added will decrease as RV1 is turned up. V1b is the second gain stage configured similar to before, C16 is added across the anode resistor R23 to smooth out the top end. V2a is configured has a cathode follower, this lowers the impedance to drive the tone network. The Tone network is passive and controlled by RV2. This is a dual ganged potentiometer, one part of which effectively controls the mids (RV2B) while the other part inversely controls the treble (RV2A). R12 and R13 act as a potential divider to lower the signal sent to input of the driver stage. This again is a common cathode voltage amplifier. The output of this drives the control grid (grid 1 - V3 pin 5) of the power valve via R15, the grid stopper resistor, and R16, the grid leak resistor. POWER STAGE The output device fitted at the factory will be an EL34. This is configured as a cathode biased, single ended, class A power amplifier with the screen grid connected for pentode operation. However, due to the design of the power stage, the biasing and output transformer, several other octal based power valves can be used, this is fully explained in the operating instructions. The biasing point and quiescent current is set by R26, which is bypassed by C14 for extra gain. 2 OUTPUT TRANSFORMER AND SPEAKER CONNECTIONS The output transformer has secondary taps for 16 and 8. The 16 tap is used to drive the External Speaker Output, SK3. When a jack plug is inserted into SK3 the internal speaker is disconnected. The two LINK positions are provided on the PCB so that different impedance internal speakers can be used in production. Depending on whether the internal speaker is 16 or 8 the correct LINK should be fitted. This has been done purely so that different impedance speakers can be used if there are any problems with supply. POWER SUPPLIES Both supplies, HT and ac filament supplies have secondary fusing on the PCB. This is to protect the mains transformer and for approvals. The HT supply is a very simple bridge rectifier diode network, with 4n7 1KV capacitors across each diode for EMC reasons. This is smoothed by C23 and C28 which provides the main supply to the primary of the output transformer. This is then further smoothed by R25/C22, R28/C21 and R27/C20 to supply the screen grid and preamp. R29 and R33 have been added to discharge the high voltage capacitors when then unit is turned off and to ensure that the initial smoothing capacitors, C23 and C28, share the voltage across them equally. The ac heater supply is simply connected via a twisted pair connecting lead to the three valve bases. Paul Stevens 3 January 1997