Rebuilt Dreamcast power supply.

Dreamcast ? · Post by **Dreamcast ?** » Wed Aug 02, 2006 4:20 am

A couple years ago, I acquired a totaled Dreamcast and made it my goal to restore it to 100%. My biggest concern was that I might not be able to salvage the power supply. As you can see from this picture, the end of it had been broken off and was literally hanging by a jumper wire. After carefully gluing the PCB back together, I painstakingly soldered jumper wires to from point to point on the broken trace routes. Fortunately, the fracture didn't cut through too many and no major components were affected.

After powering it on and letting it sit to make sure everything was OK, I tested the outputs with a voltmeter, but there seemed to be some current loss somewhere.

When I put the Dreamcast back together and powered it on, the main LED illuminated and the fan kicks on, but only for a second before the entire unit shuts down.

I can't seem to figure it out. It's not the time delay fuse (otherwise nothing would come on.). I could start pulling parts and checking each one, but is there a specific area / part I should be focusing on that may be causing this drop out?

If I let it sit for a little while, it gives gives the caps time to discharge and then I can power it back up again and it will do the same thing.

Morphv2 · Post by **Morphv2** » Wed Aug 02, 2006 8:31 am

You might have a toasted capacitor.

Ex-Cyber · Post by **Ex-Cyber** » Wed Aug 02, 2006 8:56 am

How thick are the jumper wires you used?

Dreamcast ? · Post by **Dreamcast ?** » Wed Aug 02, 2006 9:43 am

Here's a picture of my repairs and the jumpers I made. The jumpers are in red and the yellow is where the break occured. Actually, now that I look at it again, I could have used a better gauge on the ground trace. It connects some pretty major components and all I have is this little jumper. The trace itself is fairly fat.

I don't know what I could do about the others, though. It was tough enough just trying to squeeze those in there.

semicolo · Post by **semicolo** » Wed Aug 02, 2006 11:41 am

are you sure there aren't any wire missing, like on the emitter of the upper transistor ?

And yes the ground traces are large, you'd better add other bridges for it.
you can scrape a little of the green varnish off and solder directly on the trace.

Dreamcast ? · Post by **Dreamcast ?** » Thu Aug 03, 2006 4:23 am

Hello again. Thanks for all of the replies. After really beefing up the ground trace with a two jumpers (one of which is a solid 12 / 13 gauge piece of of copper wire.) I powered it up and again it powered on and then shut off.

I have gone over the board with a fine tooth comb (so to speak

), and think I may have found the problem. It might be what you thought, semicolo.

Here's a new picture. This is a picture of a board from a working unit so you get a cleaner picture. The yellow dot is the point of interest. The yellow lines are what I think are the original traces. What happened is the fracture broke the trace at the two orange double lines. I made a bridge (the red line) from the end to what I thought was the beginning, but if you look at the yellow lines, I may have forgotten to bridge the middle lead (A) from the NEC 1944 IC (PART REF # IC52).

Could someone please take a look at a board if they have one handy and verify that the trace to the (A) does indeed lead to ground? I can't tell because there's a resistor (PART REF# R60) placed right over the suspected path.

Dreamcast ? · Post by **Dreamcast ?** » Thu Aug 03, 2006 8:06 am

Nope...

I bridged that middle lead (A) to ground and then tried it again, but it still does the same thing. I'm pretty sure it's down to components now. It's nice to see that it still kicks on and everything lights up, even if it is for only a second or two.

It's like the little engine that could... except it can't.

Any last ideas before I start the tedious process of removing components and checking them?

[insert preferred religious figure] help me if it's a leadless surface-mount resistor...

rhubarb505 · Post by **rhubarb505** » Thu Aug 03, 2006 9:49 am

All I have to say is good luck. I'm sure it wont be fun checking every component.

semicolo · Post by **semicolo** » Thu Aug 03, 2006 11:55 am

If your not sure wethere there are traces or not, it won't be easy to repair it.

Are you sure your red wire is correct ? it seems to me the trace goes up to K or below C55 but not to ground (but it's hard to see on the picture).

Dreamcast ? · Post by **Dreamcast ?** » Thu Aug 03, 2006 8:46 pm

Haha, thanks rhubarb505.

Yeah, if you hold the PCB up over a tracing light (or anything else, really) you can see it really clearly that (A) does go to ground. C55 routes to the 5V output. (K) does this wierd step-like jump. Here's a picture of the actual trace routes for that section: link.

It looks like someone pried the board off with a screwdriver. Once they broke it, I don't think they would have plugged it back in, so I'm leaning more towards a problem with a trace, but I can't find anything. I think I'm going to make a schematic of a good board and go back and redo everything. Probably what I should have done from the beginning, but fortunately it broke along a pretty clear path and I thought it was going to be an easy fix.

Edit: OK, just swapped out the 10v, 1000 uF capacitor (#C59 right beside the outputs) because I wasn't getting a reading, but it's still doing the same thing. I wish I had a transistor tester to make my life easier.

Edit: This looks like a much deeper routed problem then I had anticipated. I'm getting in excess of 5V spikes off of the 3.3V output, and amperage in the .05mA range from the 5 and 12V outputs, and about 1.1mA from the 3.3V side.

semicolo · Post by **semicolo** » Fri Aug 04, 2006 12:01 pm

how are you checking amperage ?

Dreamcast ? · Post by **Dreamcast ?** » Fri Aug 04, 2006 1:27 pm

The wrong way.

With the power supply attached to the DC motherboard and the power running. Lead on ground and another on whichever output voltage I'm looking at. I forgot that it needs to be in series.

Looks like I'll have to find some way to rig a breadboard inbetween the powersupply and motherboard so I can get real readings.

FamilyGuy · Post by **FamilyGuy** » Sun Aug 13, 2006 1:19 pm

DO you know if your controller port or fan is broken /missing ??

Because when my controller port jumper was fryied , the dc would boot and then after some time reset by itself .. controller doesn't work neither ,,, and it doess the same thing if you don't pulgged the DC fan

Wish it'll be of help !!

-=FamilyGuy=-

Dreamcast ? · Post by **Dreamcast ?** » Sun Aug 13, 2006 8:20 pm

Thank you for the suggestion. Unfortunately, I'm afraid that's not it. I can use a known good power supply and everything works as it should (well sort of. The main board won't display sound or video, but you can hear the GD-ROM read / spin up as if everything was going fine. It's odd because it's not the "wrong screw / wrecked trace" problem, either. You can hear a little cackle in the speakers when the unit is turned on, but after that, nothing...).

The funny thing about this console is practically everything was totaled on it. I have no idea why, either. The power switch itself was smashed, the power button is missing, the power supply was cracked / pieces broken off, the GD-ROM unit was smashed, there's no audio / video for some reason, but out of everything that could go wrong, the one thing that usually goes wrong didn't (the controller board is in 100% working order. No blown F1 or anything.).

FamilyGuy · Post by **FamilyGuy** » Sun Aug 13, 2006 10:27 pm

lol You might try this one !

Link

It will a cheaper way to get a working dreamcast

but it'll, indeed not let you have fun soldering in it !!

wich I think is DAMN fun !!

by the way ... this mught help you a lot in your atemp :Fix everything in the DC

I wish I've been of help !!