Marantz DR-6000, MAR770, MAR775 service manual Ch1 Drain voltage Ch2 Drain current Ch3 Gate voltage

Page 25

is switched off when the current sense level exceeds the level at the output of the error amplifier.

TimeON phase : A drain current will flow from the positive supply at pin 2 of the transformer through the transformer's primary winding, the MOSFET and Rsense to ground. As the positive voltage at pin 2 of the transformer is constant, the current will increase linearly and create a ramp dependent on the mains voltage and the inductance of the primary winding. A certain amount of energy is stored in the transformer in the form of a magnetic field. The polarity of the voltages at the secondary windings is opposite to the primary winding so that the diodes are non-conducting in this phase.

TimeDIODE phase : When the MOSFET is switched off, energy is no longer supplied to the transformer. The inductance of the tranformer now tries to maintain the current which has been flowing through it at a constant level. The polarity of the voltage from the transformer therefore reverses. This results in a current flow through the transformer's secondary winding via the now conducting diodes, electrolytic capacitors and the load. This current is also ramp shaped but decreasing.

TimeDEAD phase : when the stored energy has been supplied to the load, the current in the secondary windings stops flowing. At this point, the drain voltage of the MOSFET will drop to the voltage of C821 with a ringing caused by the drain-source capacitance with the primary inductance.

The oscillator will start a next cycle which consists of the above described three phases. The time of the different phases depends on the mains voltage and the load.

TimeDEAD is maximum with an input of 400VDC and a minimum load. It will be zero with an input of 100VDC and an overload.

V2

Vosc

V1

0

Vcomp

Vsense

Vgate

Vdrain

Idrain

Idiodes

Ton Tdiode Tdead

CL 96532076_034.eps 290799

Figure 8-15 ‘Regulation’

 

 

CH1

2

 

 

CH2

 

 

PM3394B

CH3

2 V~ ALT MTB5.00us- 0.90dv ch1-

ch1

1

 

 

 

 

 

ch3

 

 

 

ch2

T

 

 

 

 

 

 

3

 

 

 

2

 

 

ch1 : Drain voltage

ch2 : Drain current

ch3 : Gate voltage

 

 

CH1

1

 

PM3394B

CH3

50mV~ ALT MTB5.00us- 0.90dv ch1-

ch1

 

 

 

ch3

1

 

 

 

 

 

 

T

 

 

 

3

 

 

ch1 : Drain voltage

ch2 : Oscillator voltage

 

CH1

1

PM3394B

CH3

20mV~ ALT MTB5.00us- 0.90dv ch1-

ch1

 

 

1

 

 

ch3

 

 

T

 

 

3

 

 

ch1 : Drain voltage

ch3 : Sense voltageCL 96532076_033.eps 290799

Figure 8-16 ‘Oscillograms’

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Contents
Service Manual Europe / Trading USABrazil AmericasPlayback & Recording and Disc This PCB contains the headphone socket CDR loader CDR main module CDL4009 or MAR770General Technical SpecificationsIII ESDService Hints Service Tools Dealer diagnostics Dealer modeStatus of player Software versions, test for defective components Electrical service diagnosticsMechanical service diagnostics Erasement of complete CD-RW DC-erase service modeCDR-Module Faultfinding treesCD-DA Disc Loaded CD R CD-RW Disc Loaded Wiring Power Supply Voltages Electrical Service DiagnosticsDisplay no CD RW+3V3 AT IC7000 Pins 5,17,21,57, Check Safety Resistors Check Flex Connection from CDR Main Board Power SupplyCD Module OPEN/CLOSECD Module Playback Description of display board Display BoardGeneral description Display controller TMP87C874FControl signals Clock signalTest instructions Supply voltagesEasy jog knob IR receiver remote controlRotary operation Push button operation Clock Signal Display board troubleshooting guide Control Signals FTD Drive LinesDescription of P816 Power Supply Unit P816Description of controller MC44603 Pin connectionsPin Name Pin function descriptionVCC Operating description of MC44603 Block diagram of MC44603Start up sequence of P816 Regulation of P816Ch1 Drain voltage Ch2 Drain current Ch3 Gate voltage Circuit description of P816 CD Main Board Troubleshooting P816Description Block DiagramMeasurements Pin Configuration Ucoil Vcoil Wcoil Input conditions conn 1006 pin Outputs connTest points on driver Hallu Hallv HallwHF Path DC SettingsHfdet Setting Transfer CharacteristicsIIS CLK11 Nmute DAC Amplifier Pink Wiring Diagram10 D5V WC01at conn.1209 WC02at conn.1400 WY01at conn.F934of WY02 WY03 WY04 CDR main board12V CD W801at conn.1500CDR Main Board Block DiagramPY46 Schematic Diagram and Parts LocationQ810 Q801 Q891 Q871 Q825 Q861 Q862 Q851 Q892 Switching Power Supply PCB. P816QY01 QY02 QY04 QN54 QN53 QN58 QN57 Q311 Q681 QF52 QF51 QN52 QN51 QG56 QN55Exploded View and Parts List Not Standard Spear Parts PackingCeramic CAP Electrical Parts ListElectroly CAP P816-RESISTORS P816-POWER Circuit Board P816-CAPACITORSP816-SEMICONDUCTORS P816-MISCELLANEOUSPP16-RESISTOR PP16-REAR Panel Circuit Board PP16-CAPACITORSPP16-SEMICONDUCTORS PP16-MISCELLANEOUSPY36-ROTARY Encoder Circuit Board
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