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OCAU Official Electronics and LCD/Case Modding FAQ (Updated 27/7/05)

Discussion in 'Electronics & Electrics' started by BlueSmurf, Jan 3, 2002.

  1. BlueSmurf

    BlueSmurf Dream it. Build it.

    Aug 2, 2001
    Baldivis, WA
    Thanks to all of the forum dwellers for their contributions.
    Special thanks to looktall for compiling ver 1.0 of the FAQ!

    This is the Overclockers Australia case modding guide, and FAQ.
    It's aim is to provide a centalised location for (hopefully) all the answers to your case modding questions, via links to tech sites, and from other OCAU members personal knowledge.
    Please feel free to add any information you think might be relevant.

    To make it easier to find what you're after, I've broken it up into various topics.


    [H]ard|OCP have changed some links on ya, the links for the case modding faq are
    http://www.hardocp.com/article.html?art=MTU3 Intro
    http://www.hardocp.com/article.html?art=MTU4 1&2
    http://www.hardocp.com/article.html?art=MTU5 Part 3

    case painting
    + Lightly sanding each coat of paint applied to your case, will give it a smoother, nicer finish.
    Be careful painting inside your machine using a paint that is "metallic".

    If the paint flakes you can end up shorting out your mobo if it lands across a data trail.

    Use only paints that are certified to work on metal

    (LED, LCD, rheobus/fanbus, etc)
    how to change case LED
    how to mod NIC LED
    how to mod keyboard LED

    LCD how-to
    baybus how-to
    guide to fanbus/rheobus
    flashing LED
    PC port pin outs
    resistor colour codes
    PC dimensions, pinouts etc


    Q: How do I run an ATX PSU without havint it connected to a motherboard?
    A: Short out the green wire to any of the black wires.

    typical single LED circuit:

    Use the following formula to calculate the required resistor:

    R = (Vsupply - Vled) / Iled

    R = required resistor value
    Vsupply = voltage of the voltage supply (12V, 5V, etc.)
    Vled = voltage drop of the LED (usually specified in its specifications)
    Iled = maximum supply current of the LED (also specified in its specifications)

    Worked example:
    I have a blue LED from Jaycar (Cat No. ZD1781). Its specifications in the catalogue are Vled = 3.6V and Iled = 20mA

    I want to connect this to 5V. What resistor do I need?

    R = (5 - 3.6) / 0.02
    R = 70

    I need a 70 ohm resistor

    Ok now how about 4 LEDs in series wired like this:


    R = (Vsupply - (Vled1 + Vled2 + .... + Vledx) ) / Iled

    R = required resistor value
    Vsupply = voltage of the voltage supply
    Vled1 = voltage drop of the 1st LED
    Vled2 = voltage drop of the 2nd LED
    Vledx = voltage drop of the xth LED
    Iled = average maximum supply current of the LEDs

    Worked example:

    I have 4 blue LEDs from Jaycar this time. Same specs as the afforementioned LED.

    I want to connect this to 12V. What resistor do I need?

    R = (12 - (3.6 + 3.6 + 3.6 + 3.6) ) / 0.02
    R = (12 - 14.4) / 0.02
    R= -120!?

    A negative resistor?? Obviously there is something wrong. We either need to use the 4 LEDs in parallel as described below, or we need to increase our supply voltage.

    Let's increase the supply voltage to 24V.

    R = (24 - (3.6 + 3.6 + 3.6 + 3.6) ) / 0.02
    R = (24 - 14.4) / 0.02
    R = 480

    I need a 480 ohm resistor

    Ok how about 4 LEDs in parallel like this:


    The formula is exactly the same as the single LED example! If we also use the same LED and supply voltage, we will notice that there is 20mA travelling down each branch. Because there are 4 branches the total current required from the supply is 80mA.

    Why don't we wire LEDs like this?:

    Remember that current takes the path of least resistance? The LED with the least resistance will get most of the current whereas the other 3 LEDs will receive a smaller proportion, dpending on their resistance.

    Note that the resistance of LEDs are around 1 ohm or less. Yes, LEDs are virtually short circuits.

    Anyway because one of the LEDs is getting more current than the others, it will appear brighter than the others. If it is sucking down a good proportion of the current, it may exceed its specs and then blow. The current will then flow through the next LED of least resistance and probably blow that. Then the next....then the last.

    what resistor would be required to operate a fan at a certain voltage.

    Fans are different to LEDs because fans are primarily resistive. Based on this assumption we can use the voltage divider rule to determine the required resistance. If all that sounds like mumbo jumbo, then don't worry I'm going to explain it step by step.

    The first thing you need to do is calculate the internal resistance of the fan. You can do this if you know any three of the fan's characteristics, power, voltage or current.

    1) Rf = Vf^2 / Pf

    Rf = internal resistance of fan
    Vf = voltage rating of fan (ie. 12V)
    Pf = power consumption of the fan

    2) Rf = Vf / If

    If = current consumption of fan

    3) Rf = Pf / If^2

    Now that you know the internal resistance of the fan, we can calculate the required resistor to bring down the voltage.

    R = Rf * (Vs - Vo) / Vo

    R = required resistor
    Rf = resistance of fan (from previous calculation)
    Vs = voltage source (eg. 12V)
    Vo = voltage you want the fan to run at (eg. 7V)

    Worked example:

    I have a 12V Sunon fan that draws 6.8W I want to run it from the 12V rail with a resistor so that the fan only runs at 9 volts. What resistor do I need?

    First calculate the internal resistance of the fan.

    Rf = Vf^2 / Pf
    Rf = (12)^2 / 6.8
    Rf = 144 / 6.8
    Rf = 21 ohms

    Now to calculate the required resistor.

    R = Rf * (Vs - Vo) / Vo
    R = 21 * (12 - 9) / 9
    R = 7 ohms

    I need a 7 ohm resistor. Note the power rating of the resistor must be equal or greater than the fan's rating. In this case, greater than 6.8W Don't use a piddly 1/4W resistor!!!
    (the above may need editing, with the info provided by cerberos)

    Voltages from Computer.

    Molex Connector
    Yellow 12v+
    Black Ground
    Black Ground
    Red 5v+

    Replacing Case LED's

    when replacing the power/hdd LEDs for ur case, sometimes there is no need for extra resistors.

    eg: abit motherboards will take a reading and change the power output to the LED according to what it needs. adding resistors will make an abit board just feed more power to the LED

    this is confirmed for the abit VP6 and the KR7A-RAID, the variable voltage output thing

    Places to buy LCD modules.

    (a little bit of everything)

    lots and lots of info here on everything electronic explained in detailed

    -Video Signal Formats Explained
    -SIMMs and Other Memory Modules
    -Understanding & Using CCD Cameras
    -Common Three Terminal Semiconductors
    -Design and Make Your Own Hi Fi Speaker Crossovers
    -Fuses - A Short Primer
    -Heatsink Basics
    -Ohms Law, Power In Circuits, AC Waveforms, Power measurement
    -Measuring AC Voltage and Current etc.
    -Wiring Diagrams - 240V, Video and Computer Connectors
    -Polyswitches and Varistors
    -Relay Driving Basics

    -Resistor and Capacitor Data
    -Soldering - How It's Done
    -Choosing A Replacement Transistor
    -Units and Conversions
    -LEDs and Laser Diodes - Care and Feeding
    -Choosing a Rechargeable Battery
    -Primary Cells and Batteries
    -Battery Terms and What They Mean
    -Variable Resistors or "Pots"
    -Understanding Decibels
    -Meter Shunts and Multipliers

    -Using & Charging Ni-Cad Batteries
    -Using & Charging SLA Batteries

    IR Remote Control Receiver

    LIRC's Schematic and details:
    - http://www.lirc.org/receivers.html
    - http://www.lirc.org/images/schematics.gif

    DSE Part Numbers

    - IR Receiver IC Z1955 $6.50
    - 4.7uF Electrolytic Capacitor R4308 $0.20
    - 1N4148 Signal Diode Z3120 $0.06
    - 78L05 5V Voltage Regulator Z6108 $1.00
    - 4k7 Resistor R1090 $0.02
    - 9pin Sub D Plastic Shell P2686 $2.20
    - 9pin Sub D Socket P2685 $1.35

    - WinLIRC and Winamp Plugin: http://winlirc.sourceforge.net
    - Girder: http://www.girder.nl
    Last edited: Apr 3, 2003
  2. OP

    BlueSmurf Dream it. Build it.

    Aug 2, 2001
    Baldivis, WA
    Case Mod FAQ - continued...

    OCAU Guides

    Case cutting on the cheap

    Installing a 120mm blowhole

    How to sand your CPU slug

    Fan Splitter (RPM/Power) Cable

    Using an automotive rheostat for fan control

    Huge Link Page of Modding Info

    Christophers Modding Zone

    Apple Mac related (not exactly modding, but some electronic stuff - thanks Moldy)


    EDIT by Manaz: The URLs were mixed up. Fixed. :)
    Last edited by a moderator: Jun 25, 2002
  3. gregzeng

    gregzeng Member

    Apr 25, 2002
  4. Cav

    Cav Member

    Jan 12, 2002

    Couple of different fan controllers that you can build yourself and are much better than their commercial versions. Also contains a couple of led voltmeters
  5. Scraperage

    Scraperage Member

    Aug 3, 2001
  6. t_rex

    t_rex Member

    Dec 23, 2001
    3031 Melb
    Just found a usefull resistor colour code calculator for those without multimeters :)


  7. d_hall

    d_hall Member

    Aug 24, 2001
    Specifications for flex ATX mobos (also includes some compaitive info for micro and vanilla ATX too). Useful for planning those put-a-system-in-something-tiny mods :)
  8. FreeFrag

    FreeFrag Member

    Jun 26, 2001
    Shepparton, Vic.
  9. DDsD

    DDsD @DDsD

    Jun 28, 2001
    From Nitrov8 -> http://www.technick.net/ Every pinout known to man :) and all sorts of misc electronics circuits / tips :)
  10. Odje

    Odje Member

    Jun 27, 2001
    Bluesmurf, i have a little update for you. I provided the Jaycar links awhile ago but there are now broken becuase Jaycar updated their site.

    Could you please change this:
    To this:
    Last edited: Jan 24, 2003
  11. Odje

    Odje Member

    Jun 27, 2001
    i had posted a larger list then this on where to buy electronics parts and LCDs

    has it got lost during the cleanups?

    let me see if i have a copy of the list on my hard drive

    i found the list

    Ricom - http://www.ricomelectronics.webcentral.com.au
    R.T.Nollet - http://www.nollet.com.au
    DSE - http://www.dse.com.au
    Jaycar - http://www.jaycar.com.au
    Oatley Electronics - http://www.oatleyelectronics.com
    Altronics - http://www.altronics.com.au
    Wiltronics - http://www.wiltronics.com.au
    Dontronics - http://www.dontronics.com
    Oztronics - http://www.oztronics.com
    Active Components - http://www.active-components.com.au
    MicroZed - http://www.microzed.com.au
    RS Components - http://www.rs-components.com.au
    Farnell - http://www.farnell.com/australia
    MicroGram Comptuer - http://www.mgram.com.au
    Rockby Electronic Components - http://www.rockby.com.au
    Last edited: Oct 7, 2002
  12. ^DevliN^

    ^DevliN^ Member

    Mar 19, 2002
    Riverton, WA, 6148
    In western Australia theres a place called Productive Plastics and they will cut you a peice of Perspex out cut to size.
    i only got a small peice for my case window. cost $5 which is their minimum Charge

    Unit 3
    65 Buckingham Drive
    Wangara W.A. 6065

    Tel: 9302 2593
    Fax: 9302 2594
    Julian: 0413 048 214
    John: 0413 048 063

    Website: http://www.productiveplastics.com.au
  13. DDsD

    DDsD @DDsD

    Jun 28, 2001
  14. RagnaroK

    RagnaroK Member

    Aug 18, 2001
    Morley, WA
    Good site for case windows and laser cutout designs

    I found this site while looking for a decent case window design.

    feel free to delet the post if u think it's useless but i have noticed some people asking for logos that arent that easy to find at larger sizes.

    hope it helps
  15. DDsD

    DDsD @DDsD

    Jun 28, 2001
    Here is a quick 'How to' for running two motherboards off of one PSU

    Courtesy of stymee of the OC.com forums :)

    Edit: Stymee has written up a more comprehensive How-to with pictures.. (pretty ones at that) which can be found here -> http://forum.oc-forums.com/vb/showthread.php?s=&threadid=155371
    Last edited: Jan 10, 2003
  16. DDsD

    DDsD @DDsD

    Jun 28, 2001
    OCAU Official LCD FAQ

    Okay ehre we go... ive had to scale down the size of the project... and go with a forum thread instead of our super LCD article conglomerate...

    But here goes, this will be more of a thread with Links to other peoples work who have already done all the hard stuff for us ;) if any of the links are dead PM me and ill remove them.

    Bit-Tech.net's Ultimate LCD Faq:

    Contains all useful titbits, links to places to buy and software low downs.

    LCD assembly

    The Ultimate LCD construction page:

    Has information on just about everything you need on making yoru own LCD, step by step instructions, and best of all, pretty pictures :)

    Pappasmurfs Crystalfontz FAQ and construction how to:
    http://www.users.bigpond.net.au/pappasmurf/CrystalFontz LCD Information - CFAH2004A-TMI-JP.pdf

    Wolfy's Parralel LCD assembly Guide:

    Setting up a serial Crystalfontz LCD:

    Setting up a hd44780 compatible LCD:


    Crystal Control Software:

    Written by OCAU's MWP, this nifty software is the ultimate in LCD control :)

    http://www.markuszehnder.ch/project...ugin/index.html - Very good winamp plugin that work with Parallel and serial units.

    http://www.geocities.com/special_4k4/ - some cool little LCD progs including HDD info, Stock ticker, Time and DUmeter.

    http://www.jalcds.de - screen based LCD software, most of the plugins are on german though. Works with Parallel and Serial.

    Im also looking for any other contributions OCAU members would like to make to this thread, feel free to post in this thread, ir if you have a larger article, we can throw it up on the main page.

    Additional links to other information is also appreciated. :)
    Last edited: Jan 24, 2003
  17. The C Man

    The C Man Member

    Dec 24, 2001
    Dreaming of Electric Sheep
  18. DDsD

    DDsD @DDsD

    Jun 28, 2001
    LCD config and Troubleshooting guide

    Here is a nice little step by step guide written by Michael Sobik, the author of the BIG article linked to in my first post, he has written this guide specifically for us :) Big ups to Mike! :)


    Hitachi HD44780 Controller debug HOWTO
    Michael Sobik ( msobik@hotmail.com )
    v1.0, 26 January 2003

    Revision History

    Revision 1.0 01-26-2003 Published by MLS
    First publication

    1.0 Introduction

    So, you've decided to take the plunge and wire up a Hitachi HD44780
    compatible LCD display to your computer. You read and followed my
    guide here:


    but when you hook everything up and turn it on, the LCD either doesn't
    work properly or it releases it's stash of magic blue smoke. If you
    fall in the former category, then this guide will help you solve your
    problems. If you're in the latter guide, this guide is useless to
    you, as you've already destroyed your display.

    If you've followed all the steps in my LCD HOWTO and you still can't
    get your display working, read the following short article and let's
    see what we can do.

    2.0 First things first

    On power up, you should see two black bars for a 20x4 display. These
    indicate a properly initialized display. If you don't see them, try
    fiddling with the contrast potentiometer. Turn it all the way up and
    all the way down. If you don't see anything, check all your power
    connections. From the source all the way to the LCD. You need to
    make sure the display is initializing properly before you try sending
    it any data.

    Also, check to make sure the backlight is powered on. If not, it's
    either already burned up, or you're not supplying it with power.

    Debugging the LCD's power and backlight are the easiest steps and
    should be performed first, before you start investigating the data

    Next thing to do is check all your solder connections. Most problems
    you'll encounter will be because of faulty wiring. What you want to
    look for is small clean solder joints on all your connections. Check
    each pin (or solder pad) on the LCD and make sure you don't have any
    bridged contacts (these are contacts that are touching). A small
    magnifying glass is a great help.

    After that, check each one of your components, resistor,
    potentiometer, wiring harness for the same things. Make sure the
    solder joints are clean, solid, and not shorted.

    Now check your wiring harness. This is especially important if you've
    used a solder type DB25 connector and removable housing. Make sure
    that the solder pins on the connector are bridged.

    If you find any problems with your solder joints, unsolder the
    connection and redo it.


    At this point I'm going to assure your display's backlight comes on
    and that it initializes. If not, keep checking the power connections.
    This section will help if you're display is powered up, but you're
    seeing garbage on the screen.

    If you've checked all your joints and haven't found any problems, it's
    time to delve a little deeper.

    First, check your software for any settings. LCDproc for Linux, for
    example, allows you to configure the program for different wiring
    schemes. The diagram I provided in my guide is the "winamp" style.
    Make sure your software is configured to use the wiring diagram you've

    Also make sure you've configured it to use a HD44780 or "generic
    parallel" display, and that it's set to 20x4 (or whatever) size.

    Check your progam doc to make sure you don't need any sort of special
    parallel port software like port95.

    Change your bios settings that control the parallel port from ECP to
    EPP or the other way around. Check your program's doc for details on
    which setting to use.

    Make sure you're using the correct address for the parallel port. For
    Windows XP:

    - right click "My Computer"
    - choose "Properties"
    - choose the "Hardware" tab
    - choose the device manager
    - expand the "Ports" section
    - right click "Printer Port (LPT1)"
    - choose "Properties"
    - choose the "Resources" tab

    I'm pretty sure the first address of the first address range is what
    your software should be configured to use. This will probably be


    Okay, software out of the way and your display still isn't working.
    Now time to tack the data cable wiring.

    Check your parallel port to LCD mapping and confirm that you've hooked
    up the correct wires from the DB25 connector to the correct pins on
    the LCD.

    If everything looks okay, try downloading this program from CrystalFontz:


    What it allows you to do, is set all the data pins on the parallel
    port to be low (or 0V). Then one by one vary the pins to high and
    confirm that the pin you've told the software to vary high is indeed

    The only thing to be aware of is if you're parallel port to LCD pin
    map is incorrect, then you can check the pins all day, get the proper
    results, but still have errors. So double check your mapping first.

    To use the software, hook your negative multimeter lead to the LCD's
    ground. Set all the parallel pins to 0. Then pick a single pin and
    vary it high. Find the pin that should be high on the LCD and hook
    your positive multimeter lead there. Your meter should read +5V. Now
    touch the positive meter lead to every other pin on the display. You
    should get 0V for every one.

    If you find another pin that has voltage (excluding backlight, power,
    and contrast pins) you have a short in your data path somewhere.
    Examine the entire path for those two wires, find, and fix it.

    Repeat this process for every pin that the software allows you to


    Hopefully, at this point you've solved your problem. Because I don't
    have any more advice for you!

    If you're display still isn't working try searching the CrystalFontz
    forum here:


    If you can't try anything, then post your problem. The guys over
    there are really good about helping out, even though parallel displays
    for end-user installation are officially unsupported.

    If you're really desperate, I've been known to help via email. You
    can reach me here:

    msobik@hotmail.com (or just post in the forums ;))

    Good luck and have fun!
  19. adzza

    adzza New Member

    Jun 27, 2001
    That guy at www.virtual-hideout.net makes it so plain and simple.
    I'm only new at case modding. But I hope to be able to post my PCDB Entry sometime soon. :D
  20. Recharge

    Recharge Member

    Sep 5, 2001
    yet another page showing how to set up an lcd


    quick Q: how do you work out the value of a Potentiometer?

    as I have a few different ones here from pulling apart electronics over the years.

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