Philips DV29 Overview, Power supply board Non-switching, Switch mode, Power supply main board

FMJ Dv29 Circuit description.

Overview

The DV29 is effectively a no compromise version both electronically and mechanically of the DV79.

The player is based around acclaimed Zoran Vaddis V chipset coupled to high specification Wolfson D to A converters for all six audio output channels, also featured in this design is a HDMI transmitter with digital Video and a Audio output capable of Digital Surround.

The DV29 and the DV79 use the same main board and power supply stage but with many of the components either upgrade or replaced with different topologies, many of the critical audio/video components with 0.1% tolerance within the DV29 and we also have an extra toroid power supply for the Audio stages.

Both the HDMI chip and Video encoder are of a higher quality than those found inside the DV79.

Power supply board.

Non-switching

Mains power arrives at IEC inlet socket SKT1 and is filtered by EMC choke LI and Y caps C3 and C4, mains switch SW2a/b switches both Negative and Live phases before the power reaches the mains select switch at location SW1 the switch allows the primary windings of the transformer TX1 to be wired in either Parallel or Series configuration.

The Bridge rectifying Diode package at location D1 forms the basis of the conventional power stage and supplies a VN35V6 (-35.6v) to the Switch mode stage, transistor TR1 is biased by 2v7 Zener diode DZ1 and allows for the series Zener diodes DZ2, DZ3, DZ3 to supply the VN13V5 and VN19V rails.

We will also see a simple A.C present circuit this is used for delayed output relay operation and fast relay closure under interrupted supply conditions thus preventing op-amp offsets from reaching the Audio output sockets.

Switch mode

The switch mode supply is formed around the Driver/Control chip IC1 UC3843 (used in regulating mode). The chip is referenced the –36.5V supply line and the Digital ground DGND, the supply for the chip is formed by the 12v Zener at location DZ6 and can be seen on Pin 7 as VCC. The power supply allows for the switch-mode to be tied the to Audio sampling frequency for any given compatible format see Fig 1.

Fig 1 PSU clock control and IC305 line status

Fs	PSUFS1	PSUFS0	PSUCLK
Frequency	Pin 11	Pin 12	Output Pin 5
select	IC305a	IC305a	of IC305a
44.1 kHz	0	0	44.1 kHz
48 kHz	0	0	48 kHz
88.2 kHz	0	1	44.1kHz
96 kHz	0	1	48 kHz
176.4 kHz	1	0	44.1 kHz
192 kHz	1	0	48 kHz
Others	1	1	OFF

The PSU sync signal is driven into the power supply via Resistor R9 if no Sync is present the unit is set to free run at xxxx due to the RT/RC network attached to Pin 4.

IC1 is running in regulated mode and monitors the voltage output on the +5V and +3V3 D.C lines, the two voltages are summed by TR8 and Driven into the VFB and Comp inputs of IC1, the Voltage is then regulated by changing the time base of the PWM output at pin 6 (longer the time base the lower the voltage), the PWM switching frequency is driven into the switch-mode transformer by the high speed Nmos device at position M1, R5 is used to sense the Current across the gate of the Nmosfet and in the event of a short circuit will safely shut the power supply down. We derive the 12v Mech supply from the output of M1 using the Ultra-fast Diode at location D8 to rectify the PWM line.

The D.C outputs from the switch mode have extensive switch mode noise removing filters these are seen as 100n caps down to ground and Wire wound inductors in series with the supply rail.

Power supply main board

All the power supply rails are supplied to the main board via the 32 way FFC conector at location CON1001.

The Digital supplies from the switch mode stage of the power supply arrive as 3V3D, +5VD and +12VD we also see the Display board power supplies arrive as –19V, -9Vand –13.5Vall of the supplies have a second stage of implemented on the board to remove all traces of ultra-sonic noise.

The 3V3D rail is the main 3V3 rail used to power the digital circuitry; +5VD is used for all 5v Digital/Video supplies the +12VD is used for Scart switching and to power the HDMI circuit (not DV78).

The 1V8 rail is derived from the 3V3 rail and is regulated by the adjustable regulator at location REG1003.