GDEMU and Pico PSU - I really need some help.

[TheSegaGuy]

Hi everyone,

I’m hoping some of the experts on this forum can assist me as I’m really at a loss with my Dreamcast. This is quite a story, but I hope the depth may help someone give me a definitive answer or at least prod me in the right direction.

My PAL VA1 console has been modded for over a year now. I’ve slowly added more to it, and at current standing it’s got GDEMU, Pico PSU (Chriz2600 design), Noctua fan, and modded port board with new battery, LED and fuse.

Around the August time, my 5.15 GDEMU started acting weird; the textures would vanish in Crazy Taxi after 20 minutes, the audio would garble and it would eventually freeze and reboot. Upon turning the machine off and back on, the boot animation would be slow, stutter, blink, and/or be accompanied by very slow, spooky almost audio.

Leave the console off for 5/10 minutes, it would boot fine but regardless of game chosen, the crashes were the same; 20/30 minutes, textures and/or audio, freeze and crash/reset.

Clean the pins! I must have the cleanest pins in any Dreamcast by this point. Ruled that out.

Tried another SD card, same deal.

I have also tried booting the console with the Pico and a GDRom drive and it booted as expected to the dashboard. I have no discs to try but I did read on the GDEMU site that the GDRom and motherboard does not have under voltage detection like GDEMU, so you can return to the drive config and believe everything is fine?

Now here’s the kicker. I blamed the GDEMU clone and binned it, bought a 5.15b clone with the metal SD slot in September, and for two months it’s been fine … until two weeks ago. The same issues are now rearing their heads once more.

A friend sent me a spare PAL Dreamcast, he botched a DCHDMI install, the sound chip is missing some pins, but the components are all there.

I tried his PSU with my fully modded console, I got crashes.

I tried my GDEMU and Pico in his console, no sound as expected, but same issues.

I then “built” a console which had my motherboard and GDEMU but with the stock fan, stock PSU, and stock controller port board.

It worked. It ran for over an hour, I had found the fix … undervoltage detection on the GDEMU was causing the crashes and the stock PSU was providing all that lovely constant flow of juice.

Until …

I was upstairs, one of the kids had been sick and between bathing them and cleaning up after them, I forget the Dreamcast was downstairs running away.

I came back downstairs, and it was off. Dead. No smoke or smell, just dead.

I took the top of the shell off, I hadn’t screwed it back together, and pressed the power button, which was greeted by a low but audible whine. Turned it off immediately.

On the PSU, the largest capacitor near the front of the PSU (35v 1000uf) was domed at one side and when viewing front on, slopes from left to right. All the caps were totally flat when I first powered it on. There’s also no leakage from this capacitor.

And while the 12v regulator wasn’t removed from the PSU, it should still have been ok to run for 2 hours without a cap popping? There’s no leakage or burn makes anywhere on the PSU.

Can I put the capacitor popping down to bad luck? Was that cap just ready to go?

The combo of GDEMU and Pico PSU has been tried on two different PAL motherboards and crashes on both.

The only time I got a flawless working Dreamcast was when I went back to the stock PSU, but 2 hours running seen a cap pop.

Was the first GDEMU I binned actually ok, or was something in the system “burning it out”, and the same has now happened to the two month old replacement?

I am totally lost and have tried every possible troubleshoot I can imagine.

Help! Please.

[Motoracer5]

Can you find another PSU to try? That is what it sounds like to me. I had PSU problems that manifested in strange ways, ended up using a PSU from DreamMods and all is well now. You could try recapping that stock PSU and see if it works

[TheSegaGuy]

Can find another PSU to try? That is what it sounds like to me. I had PSU problems that manifested in strange ways, ended up using a PSU from DreamMods and all is well now. You could try recapping that stock PSU and see if it works

Yeah, I’m going to get a loan of another stock PAL PSU from a friend and try that, I was just worried that my Dreamcast fried the cap in that PSU, as even with the 12v regulator it should run for more than two hours without popping, albeit with the extra heat.

Everything does suggest it’s the Pico causing under voltage but it was more in case any “danger signs” leapt out at others on here in terms of the system doing something wrong rather than blaming everything on the PSU.

I’ve had a look over the solder work on the Pico and under the 5 PSU pins on the mobo and I don’t see any cracks or slackness.

My worry is I borrow my friends stock PSU and that blows too, although given that just that capacitor has gone, hopefully I can replace that and it’ll fire up again? All the other caps look as they were. Maybe that cap was just ready to go, but that seems far too circumstantial for my liking!

[xzer0PL]

I had the same problem. Strange slow audio, game reset. I started to make some experiments, and I figured out that old connector is faulty. I couldn't find the same type of connector, so I decides to use a connector with the same pitch. I soldered it to atx power supply cable and it works great. I think in original power supply connector is the worst part. Here are photos.

[TheSegaGuy]

I had the same problem. Strange slow audio, game reset. I started to make some experiments, and I figured out that old connector is faulty. I couldn't find the same type of connector, so I decides to use a connector with the same pitch. I soldered it to atx power supply cable and it works great. I think in original power supply connector is the worst part. Here are photos.

Thanks for that. By connector do you mean the connector on the Pico was faulty or the connector on the motherboard with the metal pins?

Someone has also suggested to me that my GDEMU clone could be drawing an out of spec load from the PSU and breaking/blowing them?

But if that was the case then the Pico wouldn’t have worked when I put the GDROM drive back in, even allowing for the lack of under voltage protection.

I just don’t know where to go next with this console

Do I get a stock and remove the 12v regulator?

Do I go for a DreamPSU or DreamPower alternative to the Pico PSU?

Or do I buy an alternate to the Pico PSU and a new GDEMU clone? Did my GDEMU blow the capacitor on the stock PSU?

I’m just lost at this point.

[megavolt85]

But if that was the case then the Pico wouldn’t have worked when I put the GDROM drive back in, even allowing for the lack of under voltage protection.

does your console work with PICO and GDROM installed?

[TheSegaGuy]

But if that was the case then the Pico wouldn’t have worked when I put the GDROM drive back in, even allowing for the lack of under voltage protection.

does your console work with PICO and GDROM installed?

Yes, it does although by working properly I mean it boots properly and goes to the dashboard as expected and responds as expected when opening/closing the lid.

I don’t own any physical discs any more, so was unable to run a game for an hour to test that aspect.

However on the GDEMU site it does say that putting the drive back in can appear to “fix” the issue as the drive doesn’t have undervoltage detection like GDEMU does.

[megavolt85]

However on the GDEMU site it does say that putting the drive back in can appear to “fix” the issue as the drive doesn’t have undervoltage detection like GDEMU does.

do you have a multimeter? you need to check the voltage that your PICO gives out

[TheSegaGuy]

So an update …

I purchased a DreamPower PSU from Coaster2k on eBay, and it’s worked great.

Tonight, was on a monster run on Crazy Taxi. 70 mins in and on $42k with 32 seconds on the clock.

Suddenly the music stutters, stops, and the road and backgrounds begin to vanish - same as before just a lot later.

I can power off and back on without issue and get back to any game and the LED on the GDEMU is off when it happened (as opposed to flickering pre-DreamPower).

Could it be the build/GDI I’m using? It’s a TOSEC rip.

[fraggle200]

So an update …

I purchased a DreamPower PSU from Coaster2k on eBay, and it’s worked great.

Tonight, was on a monster run on Crazy Taxi. 70 mins in and on $42k with 32 seconds on the clock.

Suddenly the music stutters, stops, and the road and backgrounds begin to vanish - same as before just a lot later.

I can power off and back on without issue and get back to any game and the LED on the GDEMU is off when it happened (as opposed to flickering pre-DreamPower).

Could it be the build/GDI I’m using? It’s a TOSEC rip.

Jeez, you're not having much luck here at all. 2 ways to rule out the image being the issue would be either to get another version of the TOSEC GDI from the internet archive , search for "manydumpedgames". the whole TOSEC set was put up there for the 20th anniversary. Or go to Dubcity's great PAL/USA collection and get it from there. https://www.dreamcast-talk.com/forum/vi ... 22&t=13313 bonus from there is that it'll be truncated already as well so will save on a bit of bandwidth when downloading it.

At this point, I'd questioning the motherboard as we're now on a diff PSU, GDEMU etc etc. It's a pity that mobo I sent you had a busted sound proc otherwise it's an easy swap to at least rule out the motherboard. Spose you could still swap it in, if you still have it and let it run. there's no sound but thats only cos the pins are broken, not cos the chip is faulty so it'll still be working as hard, you just won't hear it. Worth a shot at this point.