PROJECT: REVERSE ENGINEERING

10th October, 2020

REVERSE ENGINEERING ON DVD
PLAYER

Youtube link:- https://youtu.be/9WViw8nSrhE

NAME:-SUBHASHREE PANDA
REG. NO.:- 18BEC0571
GUIDED BY:- Dr. CHILUKURI VENKATA MAHENDRA
VELLORE INSTITUTE OF TECHNOLOGY, VELLORE,TAMIL
NADU

INTRODUCTION
For this project, I reverse engineered an old DVD-Player using proper
SOP methods. I was required to disassemble and reassemble to a
working product. There were limitations on disassembly. I did not
have the ability to de-solder, so some components were not broken
down to the absolute smallest they could be. I did not have access to
calipers or a thread gauge, so screw size was not able to be determined.
I also did not feel comfortable taking apart the circuit boards. So, for
this project, the parts containing solder joints and circuit boards were
treated as one assembled part. I was working with a limited scope
and understanding pertaining to reverse engineering. The goal of this
project is to expand that scope and to expand our knowledge on the
topic.

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This DVD Player is actually low cost. We can buy it for less than 30
dollars. The way they have been able to reduce the cost, is part of
it is that the actual chips inside it needed to make it run have come
down in price & part of it is that they have been able to simplify the
components on the board tremendously.

LITERATURE SEARCH
For this section I was told to give a brief history on the DVD drive.
The Digital Video Disc (DVD) drive was born in controversy. Fol-
lowing the war between VHS and Betamax, the disc war of the mid-
nineties between Phillips / Sony and other multimedia companies had
begun. Phillips and Sony were developing the Multimedia Compact
Disc (MMCD) and Toshiba, TimeWarner, Matsushita Electric, Hi-
tachi, Mitsubishi Electric, Pioneer, Thomson, and JVC were all co-
developing the Super Density Disc (SD).
The President of IBM at the time saw that the two ideas were headed
to war and proactively sought to unite the two fronts into one stronger
design. With concessions from both sides, they united and produced
the DVD specification Version 1.0 in 1996. DVD was designed in 3
different specifications: DVD-R, DVD-RW and DVD-RAM, a read-
only, re-writable, and read/write (only playable in ram drive). This
developed from single layer discs to double layer double sided discs
and ultimately paved the way for Blu-Ray. The DVD drive has since
flourished at the main form of multimedia until just recently as sales
are beginning to decline in favour of newer technologies such as flash
storage and cloud storage.

ELEMENTS OF THE DEVICE

There are several key components to this device:-

1) Power supply

2) The control board

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 3) The CD tray as well as the laser itself

4) The external housing

1. SWITCH MODE POWER SUPPLY:-

1) Fuse

2) Safety Capacitor

3) Induction Coils

4) Diodes

5) Resistors

6) Capacitors

7) Transformer

8) IC Chip

9) Opto-Isolator

10) Shunt Regulator

2. MICROCONTROLLER BOARD:-

1) EEPROM

2) CPU

3) Clock Chip

4) Video & Audio Processing Chip

5) Op Amp Chip

6) Motor Controller Chip

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3. CD DRIVE /DVD DRIVE

1) Motors

2) Control Switches

3) Metal Brackets

4) Rubber Pieces

5) Metal Bars & Contact Points

CIRCUIT DIAGRAM WITH SPECIFICATIONS/RATINGS

Fig (i):-Location of PC boards

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 Fig (ii):-Circuit Diagram of DVD player:- WIRING &
SCHEMATICS

OPERATION OF THE DEVICE

A DVD player is very similar to a CD player. It has a laser assembly
that shines the laser beam onto the surface of the disc to read the
pattern of bumps. The player also decodes the audio stream and sends
it to a Dolby decoder, where it is amplified and sent to the speakers.
The drive consists of three fundamental components :

Drive Motor : It is used to spin the disc. The drive motor is precisely
controlled to rotate between 200 and 500 rpm, depending on which
track is being read.

Laser and a Lens System : The light from this laser has a smaller

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wavelength (640 nm) than the light from the laser in a CD player (780
nm), which allows the DVD laser to focus on the smaller DVD pits.

Tracking Mechanism : It can move the laser assembly so the laser beam
can follow the spiral track. The tracking system has to be able to move
the laser at micron resolutions.

Fig (iii):-DVD Player (TOP view)

So, the way a DVD player works :-

• Underneath of DVD, there’s a motor and that motor spins’ caus-

ing the disc to spin.
• Then, there’s a lens, a reflector and a laser diode.

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 The laser diode shines the light on the reflector and it goes
through the lens and focuses on the DVD.

• The DVD reflects back the light down and there is a light collector.

• Then it sends that information via pulses of electricity back to

the microprocessor.

It’s never safe to plug in an electronic device when it’s open. What’s
going to happen is the tray is gonna come in & the back plate gets
lowered down to make room for that tray & then it will be seen spooling
up. Then, the laser/laser assembly will start sliding across the DVD
& that will be notified or indicated by the LED.
When the CD goes into the tray & starts spooling up & what we’ll see
is that the power is being fed from this board all the way over to the
control board. Then, the control board will tell the motors what to do
& gathering information from the laser. Further, it’ll send to the ports
which go out to our TV & show up as signal.

DESIGN OF THE DEVICE

A DVD player is designed much like a CD player. They also have an
outer plastic housing and come complete with plastic buttons on the
front panel.
After the removal of the front panel of the unit/device:-

1) The front panel basically is an injection model plastic piece(e.g.-

ABS plastic)
2) It houses the slot through which the CD tray comes out of

3) It also houses a window that the infrared from the remote control
can penetrate to tell the thing what to do.
4) It has another little spot for an LED that indicates whether the
device is ON/OFF.

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 5) So fairly, a simple design it is.

SWITCH MODE POWER SUPPLY FOR DVD PLAYER:-

Switch mode power supply operates at a higher frequency whereas
linear power supplies operate at a lower frequency. The key differences
are that switch mode power supplies tend to be smaller in form factor.
They produce more Electromagnetic interference, so they have a lot
more filtering but they also operate with much more efficiency. They
can change the amount of power supply & they don’t use near as much
power as a linear power supply.

Fig (iv):-SWITCH MODE POWER SUPPLY

COMPONENTS OF SWITCH MODE POWER SUPPLY:-

1) There is a unit for power supply where the power comes in from
the house.

2) FUSE :- This is used to protect the house from any failure on

the board. So, if there’s a failure; the fuse will also fail.

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3) SAFETY CAPACITOR:- This is designed to fail in the case
of a short on the board. And therefore it’s got all these markings
on it for regulation.

4) INDUCTION COILS:- It’s basically used to filter out noise

from the power supply( Since the power supply operates at a
higher frequency, hence will produce more noise.)
5) 4 DIODES:- These diodes prevent current flow in one direction.
So, they act like an electrical valve. Hence, these 4 diodes are set
up to act as a Bridge rectifier.

6) RESISTOR:- This resistor helps the board in current sensing.

7) CAPACITORS:- They are basically a part of an electromag-

netic interference filter & they help to clean up the voltage for
that purpose.

8) TRANSFORMER:- The transformer used here is of high fre-

quency. In order for a transformer to function, there has to be
a change in voltage. The way we make change in the voltage is
what’s called PULSE WIDTH MODULATION.
The transformer steps the voltage down from 120V to both 12V
& 5V.

9) The pulse width modulation(PWM) is being regulated by an IC

chip. Hence, that IC chip controls the PWM.

10) There are a number of resistors all over the board. They are to
protect the circuitry on the IC chip most likely.

11) There are as well diodes that control the flow of current.

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 12) OPTO-ISOLATOR:- The opto-isolator is used to sample out-
put voltage & regulate it during the different load conditions.

13) SHUNT REGULATOR:- It basically functions like a Zener

diode or a variable Zener diode. A Zener diode allows current to
flow in one direction to a certain point and then above the certain
point , it allows current to flow in both directions. So, this sort
of functions like a variable Zener diode.

Fig (v):-Switch Mode Power Supply

MICROCONTROLLER BOARD:-
The power comes into the board through the plugs and then flows into

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the sockets. There are a number of different components and chips on
this board which are discussed below.

1) EEPROM:- (ELECTRICALLY ERASABLE PROGRAMMABLE

MEMORY CHIP) This memory chip stores an index of com-
mands for this board, even when the power is shut off.

2) CPU:- (CENTRAL PROCESSING UNIT)

This chip controls all the functions of this board as well as the
functions of the entire unit. This chip basically can go and pull
indexed commands. It sort of acts as a memory.

Fig (vi):-MICROCONTROLLER BOARD

3) CLOCK CHIP:-
This chip has a little quartz crystal in it. And, Quartz has an
interesting property. When it is squeezed ; it can emit a small
electrical signal or when just electricity is run through it, it’ll
expand just slightly. And so, because of that, it is very consistent
in the way that it responds to the electricity & very consistent in

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 the way that it expands & so because of that property; they’re able
to run electricity to it & get it to expand & get a return voltage &
then they can determine a very precise timing. Anyway, it allows
this board to synchronise itself which is really important when we
are reading a lot of data from a disc & we have to make sure all
those 1’s and 0’s end up in the right place & everything’s happen
in sync.

4) VIDEO & AUDIO PROCESSING CHIP :-

This chip is the Video & audio processing chip. So, once the data
comes in ;it’s routed through the CPU to this, & processed &
converted into a signal that your TV & stereo will understand.

5) OP AMP CHIP:-
This chip basically stands for operational amplifier and it will
boost the signal coming out of this chip. So, this chip’s signal
may be very weak and in order to get it to travel down the cords
to go your TV & stereo, we need to boost the signal & increase
the voltage.

6) MOTOR CONTROLLER CHIP:-

This chip controls the direction & speed of the motor & it does that in
a very precise way. So, it works with the CPU chip to make sure that
the motors are moving in the right direction & at the right speed.

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 Fig (vii):- MICROCONTROLLER BOARD (top view)

Now we are going to discuss about the CD drive /DVD drive itself:-
The power for the motors comes through the wires. There is a chip
that controls the electrical impulses & through the wires & tells the
motors to drive the tray out, spin the spindles or move the laser back
and forth.
So, there are 3 functions present and hence that requires three motors.
These motors are present in the rear part of the DVD player.
First, we’ll look at the structure and mechanical components.

• As expected, there are 3 motors:-

1) First motor causes the spindle to turn around.

2) Second motor actually drives the gears and causes the laser
assembly to move.
3) Third motor causes the tray to slide out from the actual player
so as to put the disc in and have it spun around and read.

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 Fig (viii):- DVD player with CD attached

• CLOSED LOOP CONTROL SWITCHES:-

It is very important that everything remain in true alignment
and that’s what these switches are there for. These switches reset
everytime the CD tray opens and closes.

• METAL BRACKETS:-
Two motors are held over this metal bracket( One motor that
turns the spindle & the other motor that moves the laser).
Both these motors are mounted on this metal bracket which means
that they are very stable and solid and the bracket has been made
rigid by having these bends in it; so that it gives it a really strong,
sturdy & rigid.

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• RUBBER PIECES:-
There are these two little rubber pieces and they actually allow
the drive plate (metal plate) to drop down.
Again the metal is really critical because it provides that rigid
platform & helps to maintain that dimensional stability which is
required to keep everything just locked in place.

• METAL BARS:-
These bars are tightly connected to this metal bracket, and they
allow for the laser to track very smoothly across this edge.

• CONTACT POINTS:-
There are contact points and there is also a long edge that helps
to maintain very consistent, accuracy and smooth motion. These
rods are smooth and polished and allows the laser to track in a
very smooth pattern.

• And also there are injection moulded parts and the ribs add stiff-
ening and strength and complete the DVD drive and allow us to
fasten all the different components together.

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 Fig (ix):- Location of Motors
Now we will have a glance at the laser assembly :-

• It’s comprised of a number of parts.

• It has a laser diode, series of reflectors, lens, a laser/light sensor

and also an adjusting mechanism.
• There are two Neodymium magnets.

These magnets are very strong for their size. And that means it’s a rare
earth magnet and they tend to be very powerful permanent magnets.

• We also have two different coils made of copper.

• And the lens is mounted on the wires in between and it can shift
and move.

This mechanism allows for fine tuning adjustment of the lens.

• SENSOR:-
It collects the reflected light and sends that information back.

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 • LASER DIODE:-

It shines the laser light that gets read; that hits the disc and gets
reflected and read by this sensor.

Fig (x):- Working mechanism of DVD player

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MATERIALS USED IN MAKING THE PRODUCT
A variety of raw materials are used in the construction of DVD players
and disks.

1) Glass is used to make the laser and other diodes in the system.

2) The primary components on the circuit board are made from sil-
icon.
3) Aluminium metal is used for the housing as well as a hard plastic.

4) The base material of the disks is plastic.

5) They are additionally coated with a silver coloured layer and a

thin gold layer.
6) The surface of the disk is further coated with a hard layer of
lacquer to protect it from damage.

The components of a DVD machine are typically manufactured by

separate companies and then assembled by the DVD manufacturer.
The production of the component parts is a highly specialized process,
and only a few companies are equipped to supply the entire industry.
When all the components are ready they are assembled to produce the
final product. The electronic board is hooked up to the rest of the
machine and the main cover is attached. The DVD machine is then
sent along to a packaging station where they are boxed along with
accessories such disks, manuals, and power cords. They are then put
on pallets and sent to distributors and finally customers.

APPLICATION OF THE DEVICE

1) DVDs can be used for a variety of applications including movies,

audio systems, computers, and video games.

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 2) Since the information stored on these disks are electronic, the
picture quality is estimated to be three times better than conven-
tional VHS pictures. Additionally, the picture will not degenerate
with age or use.
3) Computer programs will also benefit from DVDs. For example,
programs, which used to take up multiple CDs can now be con-
densed onto a single DVD.
4) Video games will also benefit from DVD technology. Since DVDs
offer high memory and interactivity possibilities, video clips can
be included to enhance the playing experience.

THE FUTURE:-
DVD technology is relatively new. There are many areas which will
be improved in the coming years. Key developments for DVD include
greater storage capacity, improved reader capability, and an increase
in the number of movies available in DVD format.

1) Currently, the most intensely studied area of DVD technology is

increasing data storage capabilities. While the technology has
already been developed to produce 17GB disks, some companies
have found ways to store even more.

2) A new encoding technique is being developed that can create a

three-fold improvement in DVD storage. In this method, the pits
made on the disk will have varying degrees of depth. This will
allow the pit to encode for numbers from 0 to 8 instead of just a
0 or 1. It is anticipated that DVD devices using this technology
will be available during 1999.

3) A new technology has recently been demonstrated that can hold

up to 30 GB of data. This system uses red lasers and a magnetic
field to retrieve the data. The use of blue lasers may allow for
even greater storage capacity.

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 4) Another area of improvement will be found in the ability of the
DVD players to read two layers of information on a single side of
the disk. Even though DVD players can theoretically read two
layers of information both layers are rarely used because of its
high cost. As technology improves however, this obstacle should
be overcome and the full potential of DVDs may be realized.

5) Currently, one the most inhibiting factors in the development of

DVDs is the lack of a universal standard for storing and picking up
media. This is similar to the problem that developed in the 1980s
between VHS and Beta videotape players. In the near future,
this problem should be resolved when major DVD manufacturers
agree on a format.

CONCLUSION
In conclusion, I have learnt about the extensive and necessary steps
to conduct proper reverse engineering. I also learnt about the SOP
method, how to properly make a list of materials, and many other use-
ful lessons during this project. I came away with much more knowledge
on DVD technology and how much work goes into properly making an
electronic device.

SUMMARY
This project was designed in order to have the students learn about
reverse engineering and to demonstrate that we can use all of the nec-
essary and relevant steps. For this project I was expected to find a
DVD player, DVD drive, etc. (source was not specified) and conduct
the full process on my procured DVD drive. I obtained an old DVD
Player from my house itself. I took my time and photo-documented
the different parts and listed the function of each part to the best of
my ability.

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At the end of the reverse engineering process, I came away with new
knowledge about the function of DVD drives and why each part exists.
In conclusion, I have a better understanding of the steps and require-
ments for proper reverse engineering and feel confident that we could
apply these steps to other applications.
It’s relevance to the course EEE1001 topics:-

1) AC/DC Circuits:-
There are diodes set up together to act as bridge rectifier(that
converts alternating current (AC), which periodically reverses di-
rection, to direct current (DC)). In direct current (DC), the elec-
tric charge (current) only flows in one direction. Electric charge
in alternating current (AC), on the other hand, changes direction
periodically. The voltage in AC circuits also periodically reverses
because the current changes direction.
2) Digital Logic Design:-
Digital Logic designers build complex electronic components that
use both electrical and computational characteristics. These char-
acteristics may involve power, current, logical function, protocol
and user input. Digital Logic Design is used to develop hardware,
such as circuit boards and microchip processors.
And so does the Digital video disk or digital versatile disk(DVD)
which includes the optical system assembly,
internal electronic circuit board and the disk drive mechanism.The
electronic components of the DVD machine are sophisticated and
use the latest in electronic processing technology. The circuit
board is produced much like that of other electronic equipment.

3) Semiconductors:-
Inside your CD player, there is a miniature laser beam (called
a semiconductor diode laser) and a small photoelectric cell (an
electronic light detector).

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 4) Electromechanics:-

There are many electromechanical motions devices in CD/DVD Player

(for e.g.- spinning motors).
The disc drive mechanism consists of a motor that will drive the disc
in a circular motion.

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