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DREAMCAST Repair - 3

 
 

 

 
  

 

 
 

 

 
 

       

 

 

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DREAMCAST Repair - 3

Welcome to my troubleshoot & repair guide for Dreamcast game consoles. I have assembled much needed information about how to fix some common Dreamcast problems. This guide was created many years ago... the information is somewhat obsolete so I am giving it away for free!

If you find this information helpful and would like to reciprocate - please click on the links of our sponsors shown in the side columns of this website

 

Disk Reading Errors

Disk reading errors can be a real problem for Dreamcast owners. Its the classic story; you put your favorite game in the CD tray and it wont read!! Well, there are a couple of things we can try to combat this problem.

Be sure you are playing a Dreamcast CD that is NOT COPIED. Make sure you are playing a CD that is compatible with your Dreamcast version. (No Japanese games or CD's!! They wonít read) Last, be sure to clean the underside of your game CD.

First of all, clean the CD Laser Lens. See how to clean the laser lens This cures the problem about 70% of the time. If once you clean the lens and you STILL have problems keep reading...

Ok, you've tried to clean the laser lens, with no luck. So we now know there is a physical problem somewhere in the CD assembly. There are couple things you need to find out.

1) Is the CD spindle motor functioning? This is the motor that spins the CD. When you first press the power button, the CD will spin a very little bit then pause. What happens is the CD laser is focusing on the CD's starting point. It is at this time the Dreamcast really knows if there is a CD in the tray. Even if the Laser is completely blown, this should move a little bit and "queue up" (or at least try to). If its not even moving a little bit, then you'll need to replace it. *SEE NOTE BELOW

* Also check the CD tray latch! There is a latch on the CD assembly that tells the Dreamcast if the lid is open or closed, so if you have the case off you'll need to push the plastic lever back to simulate the lid being closed.. or the CD will NEVER spin. The latch is located to the rear and right, in relation to the picture shown below.

2) Is the motor for the laser slide assembly functioning? To check, push the laser lens seat away from the CD spindle. (NOT THE LENS! But the plastic assembly you see holding it, NEVER touch the lens!) If you power your Dreamcast on the lens should move back to the default starting position. If it doesnít, then you need to replace that motor. The motor is the larger rectangular motor attached to the gears that slide the laser up and down the assembly. Itís labeled on the picture below, and you can clearly see the large square-looking motor to the right.

3) Well, if you've read this far, this means that the laser is the suspect component. Underneath the laser lens is the electronics that make it work. You can clearly see the electronics in the picture. You can try to adjust the laser voltage by tweaking the potentiometer located on the opposite side of the laser. The screw is highlighted in the picture below.

Get to the laser by pulling up on the assembly. It should fold over like you see in the pictures.

You'll need a very small screwdriver. Mark your starting point in case you need to set it back to what it was before you messed with it. Turn the screw clockwise a very small amount. Try to load your problem disk. If no luck, then turn it just a bit more clockwise.

Donít over do it- you can blow your laser. Under no circumstances do you want to turn this screw more than 1/3 of a full turn. If you've gone for it, and it still doesnít work, then scrap it. Dreamcasts are now cheap, and you have a blown or malfunctioned laser. In any case, the laser will cost more to replace then it will to get a new or working Dreamcast from eBay.

The screw to adjust the laser is highlighted in red.

 

Power Supply & No Power

Dreamcasts that do not power on are becoming more and more common. These problems can't always be fixed, but the majority of these can. Most of these problems result from a faulty PSU (power supply unit). For U.S. distributed Dreamcasts, the power supply unit will convert 110-120V AC (from your wall socket) to 12V DC (for use in your Dreamcast). From there it is transferred to the DC motherboard/mainboard. Once it gets to the mainboard its real hard to track and troubleshoot, unless you are a Sega employee with schematics! Schematics are proprietary information, and are NOT available to the public. So, I have put together a little psu section here to help us out.

YOU WILL BE WORKING WITH 120V AC LIVE ELECTRICITY! DO NOT ATTEMPT THIS IF YOU HAVE NO EXPERIENCE WORKING WITH ELECTRONICS.

DO NOT DIRECTLY TOUCH THE COMPONENTS. THE ONLY CONTACT YOU SHOULD MAKE IS THE VOLTMETER PROBE TO THE TEST POINTS).


1) Open up your Dreamcast

2) Get your Voltmeter out.

3) Pug in your Dreamcast.

4) You want to check the voltage coming out of the Dreamcast. See the picture provided; There should be 12V, 5V, and 3.3VDC all leaving the psu at the rectangular connector piece. (shown in RED) The pin-out is labeled. This is where the voltage leaves the PSU. If the voltages are good at these test points, then you have a good power supply unit. If they are not good then you have to figure out why- see #5.

5) The next test point you want to test is the resistor right next to where you plug the power cord into. Itís a 1M-ohm resistor and itís labeled in the picture below. This is a great spot to check to see if you are getting power to the psu board. In many instances, I have seen this resistor burn out! Check for resistance on this resistor, if it is open then the resistor is bad and you'll need to change it!

6) Ok, so now you have no power leaving the board, and you have good power getting to the board. (And you've checked this on the 1M ohm resistor at the top of the diagram)

Next, check the resistor that is about midway down the board and to the right. (This is also shown on the diagram, itís the next reading down on the left.) The actual resistor sits vertical on the picture. Check for 45VAC at the test point shown. If you have no voltage there, or bad or incorrect voltage, you've gotten closer in isolating your problem. You'll need to continue doing a resistance and continuity check on some of the components the lead to this resistor.

If you DID get a good voltage move on to some of the other test points shown on the diagram and repeat. Continue checking until you find a bad reading on one of the test points shown. Then move backwards, checking components. If you turn the board over you'll be able to see the paths of the components and the traces that connect them.

 

Rule of thumb;

Resistors - Check for resistance, should be resistance designated by the resistor's color code. Go HERE to calculate the resistance for any given resistor color code. You want to make a note of the color bands on the resistor. Each color band has a specific value.

Capacitors- Should read open on a resistance check! Most multimeters wont test for capacitance so there's not much we can test on capacitors.

Inductors- Should read a short on a resistance! If you read an open on an inductor or on a resistor then replace it!

 


 

If your voltage readings are good from the output of the power supply unit and your Dreamcast STILL will not power on, then start removing ribbon cables from other boards. For instance, remove the ribbon cable to the controller port board. Try to power it on again, did it work? If yes then your controller port is shorted somewhere. If it didnít power on, then put the cable back in where you pulled it from. Now, remove the CD assembly. Try it again, did it power on? If yes, then the CD assembly is shorted somewhere. (You see a pattern here?)

I generally wonít troubleshoot a power-on problem past the psu, data ribbon cables and mainboard fuses. The mainboards are all surface mount IC and BGA components, very very difficult to troubleshoot if you are not a trained SEGA employee and you do not have multichannel O'scopes and spectrum analyzers. Components are cheap, especially for Sega Dreamcasts. Dreamcasts are now obsolete, and you can find replacements easily . (See ebay!)


 

Intermediate Resetting

Ok, you power the Dreamcast on and start playing. You'll be getting a good game of NFL BLITZ when WHAMMO!! out goes your Dreamcast! What the...? It just goes out, then powers back up. It may even keep doing that a couple more times.

What happened?
Well, the power supply unit transforms 110-120 VAC into 12VDC, and that power runs through that power supply whenever your power button is depressed. After a while things heat up and parts expand causing lose connections and unreliable contacts on the power supply unit. Try this to fix your intermediate resetting problem;

If your Dreamcast powers off or freezes during game play and does not correct itself, check to make sure the fan is working, also check the output of the power supply. See the power supply troubleshooting section for more info on what the voltage from the power supply unit should be. (3.3vdc, 5vdc and 12vdc)

1) Remove all connections, controllers, and modem.

2) Remove the case.

3) Remove the screws to the power supply unit. Itís the board that the power cord connects to.

4) You'll see a white connector at the bottom of the psu. There is a picture of the connector on the power supply unit on the power supply section of this guide (itís the white connector all the way at the bottom). Remove the power supply unit. You'll see that you have to pull the unit directly up to get the pins to slide out of the white connector.

5) See those pins? They used to go through the white connector, they should now be exposed. Apply some pressure to those pins, pushing them towards the back of the Dreamcast. Do not bend them, just apply a good firm pressure to them.

6)We are done. Now, put the power supply back on. Attach the screws and to the power supply and also to the Dreamcast case.

Try it now! It is the pin connections that are giving you problems. Now that we've pushed on them a little, they should have made a better connection when you plugged the psu back onto them.


Dreamcast, Sega Dreamcast and their accessories are registered trademarks of Sega. This informational list is copyrighted Aug 15, 2002 by William Schott and may not be replicated, altered, sold or distributed without written permission from the author.

Please note that attempting to open your Dreamcast game console will void the warranty. Use this guide to work on a Dreamcast at your own risk. The author is not responsible for damage you may have occurred by following this manual. Nor do we guarantee that by following this manual that your Dreamcast be fixed.

This information is for educational and informational purposes ONLY. It is not our intention to assist you in committing fraud or performing any illegal acts. As with any action you take, it is your sole responsibility to obey any regulations or laws that apply to you. The presence of this site on the world-wide-web means that it is available to a world audience, so we cannot possibly advise you on the legality of utilizing or possessing the information contained herein. You should always seek competent legal counsel to insure you are in compliance with all local laws.
We do not and cannot warrant the information, documentation or software included in this distribution service or the performance or results obtained by using this information, documentation, or software. This information on all our web pages, documentation, and software is provided "as is". We make no warranties of any kind, either express or implied, including but not limited to, noninfringement of third party rights, merchantability, or fitness for a particular purpose with respect to the product and the accompanying written materials. To the extent you use or implement this information, documentation, or software in your own setting, you do so at your own risk. In no event will we be liable to you for any damages arising from your use or, your inability to use this information, documentation, or software, including any lost profits, lost savings, or other incidental or consequential damages, even if we have been advised of the possibility of such damages, or for any claim by another party.

And NO, this document may not be duplicated, sold or otherwise distributed without consent from the author. :)

 

 
           
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                            Copyright 2003

                           By William Schott                                            

 

 

 

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