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
the information is somewhat obsolete so I am giving it away for
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Disk Reading Errors
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
* 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
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
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
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-
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
Rule of thumb;
Resistors - Check for resistance, should be
resistance designated by the resistor's color code. Go
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
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!)
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
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
3) Remove the
screws to the power supply unit. Itís the board that the power cord
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
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.
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