Group 4 - Computer DVD Drive

Hitachi-LG GCE-8400B

Executive Summary

The main focus of this product dissection was to fully disassemble a DVD-drive typical of optical drives used today for reading the data on the ubiquitous digital video disc. This particular device is intended to fit in the 5.25" drive bay of modern desktop computer towers. The procedure was to incorporate a complete product dissection including careful disassembly, component study, and reassembly. The initial phase consisted of a complete tear-down of the product and photo-documentation. Subassemblies were numbered and placed in separate containers for later identification and ease of reassembly. Each component and subassembly was studied in order to better understand its function within the unit, and how it interacted with other components in order to perform the same overall function. Once inside, the intricacies and capabilities of modern electronics can be fully realized. The product itself is able to load a DVD disc into the tray, read it through the use of a laser, convert the data into a signal readable by the computer in a package not much larger than the disc itself. After documenting a few crucial components in a 3-D CAD program the components were assembled back together. The process was straightforward and easy using only a small screwdriver and basic disassembly skills can completely remove almost all necessary components to study the product. As this was a base-model widely available device, and most certainly not intended for infinite life use, some of the components were not designed to withstand the forces necessary to disassemble it. These include many small plastic pieces and a small rubber belt that was missing upon delivery of the item.

Introduction

Product Description

• Computer CD-R/RW, DVD Drive
• Manufacturer: HL Data Storage, April 2002
• Designed By: Hitachi-LG Data Storage
• Model Number: GCE-8400B
• Laser Class: 1
• Buffer Size: 2 MB
• Access Time: 110 ms
• Internal CD-RW Storage Drive: 40X Speed
• Maximum Data Transfer Rate: 6,000 KB/s

The HL Data Storage CD-R/RW, DVD drive is used in a computer interface to read and play CD's and DVD's. It can also burn data onto a CD-R. This model is used in a variety of desktop computers and can cost in the range of $20.00-$25.00 in today's market.

Group Members

• Bryan Humes
• Brian Maisch
• Eric Klaben
• Winnie Liu
• Fahr-Deen Kadree

Before Disassembly

Purpose

The purpose of the CD-R\RW, DVD drive is to read and play CD's and DVD's. It can also burn data onto a CD-R.

Condition

The product was in fair condition, all moving parts functioned; However, the product was missing a pulley belt so it did not operate properly.

How it Works

Before disassembly our group decided how the DVD drive works. We determined that a laser read information from the discs surface. We know the disc contains lands and pits but we are unsure how the data was transfered.

Parts and Materials

Our group estimated our product would contain approximately 20 different parts and 6 different types of materials before disassembly.

Disassembly Procedure

Step	Process	Difficulty(1-5) 5 being the hardest	Tools Required	Picture of Step
1	Remove 4 screws from bottom plate	1	Phillips Head Screwdriver
2	Unplug wires and remove main computer chip. This exposes all of the parts.	2	Hands
3	Remove the laser motor by unscrewing 2 screws. Then detach the drive interface by unscrewing 1 screw.	2	Phillips Head Screwdriver
4	Take the outer casing off of the internal frame	1	Hands
5	Remove the 2 plastic holders that are holding the laser by unscrewing 2 screws. This will free the red head assembly.	2	Phillips Head Screwdriver	blank
6	Remove the red head assembly by lifting it out of the housing.	3	Hands	blank
7	Take the CD/DVD holder out by removing the the front face plate	2	Hands
8	Remove the eject gear.	3	Hands	blank
9	Remove the pulley.	3	Hands	blank
10	Remove the disc support from the internal frame by removing 2 screws. This houses the disc motor.	2	Phillips Head Screwdriver
11	Further disassemble the disc support by removing 5 screws and 3 hex screws. This frees the disc motor.	3	Phillips Head Screwdriver and Allen Key	blank
12	Remove the spindle motor, it should slip right out.	1	Hands	blank
13	Remove the height adjustor from the internal frame by squeezing the ends of it to allow it to become free.	2	Hands	blank
14	Remove the lift actuator from the internal frame by applying force to it.	2	Hands	blank
15	Remove the emergency eject mechanism from the internal frame by applying force, it should just pop out.	2	Hands	blank
16	Remove the eject motor, headphone jack, and volume control from the top of the internal frame by opening clips that hold them in place. It is helpful to use a thin object such as a pen to help you in this step.	3	Hands and Pen	blank

After Disassembly

Component Table

Part Number	Part Name	Quantity of Type	Part Material	Manufacturing Process	Image of Part
1	Bottom Plate	1	aluminum	stamped	Bottom Plate
2	Main Circuit Board	1	FR-4, steel, copper, various	printed circuit board (PCB)	Main Circuit Board
3	Sled Motor	1	aluminum, steel, copper wire	stamped, welded	Sled Motor
4	Red Head Drive Interface	1	plastic	cast	Red Head Drive Interface
5	Metal Case	1	aluminum	stamped	Metal Case
6	Red Head Brackets	1	plastic	cast	Red Head Brackets
7	Red Head Assembly	1	various; metal, glass lens	mass produced	blank
8	Disc Holder	1	plastic	cast	CD-rom Holder
9	Eject Gear	1	plastic	cast	Eject Gear
10	Eject Pulley	1	plastic	cast	Eject Pulley
11	Disc Support	1	aluminum, rubber damping	Stamped	Disc Support
12	Support Springs	1	Metal	blank	Support Springs
13	Spindle Motor	1	steel, aluminum	mass produced	Spindle Motor
14	Lift Actuator	1	plastic	cast	Lift Actuator
15	Height Adjustor	1	plastic	cast	Height Adjustor
16	Emergency Eject Mechanism	1	plastic	cast	Emergency Eject Mechanism
17	Eject Motor, Volume Control, Headphone Jack	1		blank	Eject Motor, Volume Control, Headphone Jack
18	Internal Frame	1	blank	Injection Molding	Internal Frame

Fasteners

Type	Size (inches)	Quantity	Purpose	Image
Phillips Head	3/16 x 5/16	4	Holds the bottom plate in place
Phillips Head	2/16 x 3/16	4	2 screws hold the laser motor in place 2 screws hold the laser brackets in place.
Phillips Head	1.5/16 x 1.5/16	1	Connects the laser drive interface with the laser.
Phillips Head	3/16 x 8/16 washer 4/16 diameter	2	Connects the disc support to the internal frame
Phillips Head	6/16 x 5/16	3	Holds the disc support and disc motor together
Allen Screw	.0591 x 6/16 washer 4/16 diameter	3	Holds the disc support and disc motor together

3D CAD Models

Side View	Angled View	Top View

Spindle Motor: The spindle motor is essential to the DVD drive. The disc support which houses the spindle motor lowers with the help of the hieght adjustor and the lift actuator. The lift actuator slides down through the groove in the height adjustor, which in turn lowers the spindle motor. The disc is now able to be inserted into drive with no obstructions. The disc support is now raised with the help of the same mechanisms. The spindle motor is now in the center of the disc and will spin it when the energy is provided. The spindle motor runs between 200 and 500 rpm depending on the location of the laser.

Side View	Angled View	Top View

Sled Motor: The sled motor provides a constant rate of motion for the laser. The laser motor has a series of spiral grooves in which the drive interface is connected. The drive interface is connected to the laser. As the motor turns the spiral grooves, it provides motion to the drive interface which moves the laser at a constant predetermined speed.

Side View	Angled View	Top View

Red Head Assembly: The red head assembly contains the laser, lenses, and photo sensors. The laser beam is focused through the lenses to read the lands and pits on the DVD or CD. The red head is installed on a set of rods(tracks) and is provided motion from the sled motor.

Assembly

Step	Process	Difficulty(1-5) 5 being the hardest	Tools Required	Picture of Step
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Video

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After Assembly

Does it still work? Our product still does not work after assembly. The product did not operate properly before disassembly nor were we able to connect it to a computer interface to test it.

How it Works

The CD-R\RW, DVD drive works in a general sense by converting electrical energy into mechanical energy. This mechanical energy is used first to load the disc tray into the chassis, then to spin the disc at a variable angular velocity so as to obtain a constant bit rate. This is due to the angular velocity being greater at the outer edge of the disc than at the inner edge. The device must also simultaneously transfer the rotational motion of the laser motor into a linear path from the innermost edge of the disc to the outer edge while the laser is scanning the disc. This is an interesting mechanism and can be seen below. It utilizes a spiral engraved shaft to transmit motion to a plastic interface component that carries the laser the needed distance, at a predetermined rate. The device then uses several feedback mechanisms and circuitry to convert the laser information which is a measured voltage difference into binary coded data and exports it through the use of a parallel ATA-type communication link. The data can then be processed by software programs intended for the purpose of multi-media type data interpreting.

Reflection

• Was assembly a mirror process of dissasembly?
• Reflect on the assembly process.

Energy Transfered

Electrical Energy: Electrical energy is transfered to the drive from an ordinary household eletric supply.
Mechanical Energy: Mechanical energy is transfered when...
Rotational Energy: Rotational enery is transfered when power is supplied to the spindle motor, thus creating rotation.

Types of Materials

1. Plastic
2. Silicone
3. Metal
4. Copper
5. Rubber
6. Aluminum
7. Steel

Recommended Design Changes/Improvements

Overall this product was very well designed. The only improvement we could suggest at the time of production is removing the pulley system and replacing it with a set of gears. We suggest this because upon recieving the DVD drive the pulley belt was missing, which would cause the product to malfunction. If this belt was replaced with a set of gears this problem could be averted all together. The DVD drive was very well put together and designed.

Conclusion Remarks

• Conclusion Remarks.

References

APA Style