Dreamcast-Talk.com

Hey guys, I have a Dreamcast with a few mods including 1. GDEMU 2. removed 12v regulator 3. battery holder 4. Noctua fan

I'm glad to not have to worry about the GDEMU heat issue, having removed the 12v regulator, but I'm just curious if this has any effect on the functionality of the modem and possibly ever dabbling with online play, like if I wanted to get a DreamPi setup someday down the line?

I've read conflicting opinions and rumors across the internet and I was hoping someone more technically-minded could chime in.

Cheers, thanks!

As far as I know only the karaoke addon used the 12v rail. Modem should be unaffected.

12V line uses only GDROM and AV port (RGB SCART)
the 12 volt line is not connected to the expansion port

Good to know. Excited to eventually get this thing back online. Thank you guys!

Can someone please give me a definitive answer on the following question?

I have a UK PAL Dreamcast.

I connect it to a UK CRT SD TV via an RGB SCART cable. The TV accepts 60Hz NTSC input. I run all my games in 60Hz NTSC mode.

I want to remove the 12V rail to reduce heat, since the official PicoPSU is sold out everywhere. I intend to use this guide for PAL systems:
https://www.reddit.com/r/dreamcast/comm ... gdemu_and/

Will the RGB SCART output still work?

This thread says yes:
https://www.reddit.com/r/dreamcast/comm ... _question/

But this guy did it and his RGB SCART stopped working:
https://www.cybdyn-systems.com.au/forum ... =40#p14063

I did the 12V Fix mod on my PAL Dreamcast and the RGB Scart output stopped working, this is with the official cables. Only the Hanzo VGA box worked. I prefer using RGB Scart on a CRT so I can use a light gun etc. I decided to just reconnect the 12V rail.

So which is it?

What does removing the 12V rail actually do to the output?

Why is there no definitive answer?

Why did the guy's DC stop working?!

Some places say it just stimulates Pin 8 on a SCART cable to switch the aspect ratio on your TV. I actually cut the cable for pin 8 on my SCART cables because it irritates the hell out of me. My GameCube kept activating the forced 16:9 ratio on my CRT, so I cut the cable to stop it. My CRT TVs are permanently on the RGB input channel, so I do not require the auto switching.

Also, I have a remote control to manually switch if needed.

Does removing the 12V rail actually stop a signal from going out?

Does it affect the screen updates?

Or does it only trigger the auto-switch on the TV?

I really cannot fathom why there is no definite answer to this.

Please help.

EDIT:
Here is another example:
https://retrozone.co/forums/threads/dre ... moval.573/

And again, one person makes a statement, another asks for confirmation, and there is no definitive consensus.

WHY?! I just need to know, is the 12V only for aspect selection, or does it actually power the sending of signal??

EDIT 2:
https://8bitplus.co.uk/projects/dreamca ... ode-board/

Removal of the regulator is usually the best way to go, except it will remove all 12v lines from the system including the AV port. You might find that RGB video stops displaying over SCART. This seems to depend on the RGB cable its self, and you may not have a problem if its wired to use 5v for video blanking.

This conflicts directly with the above Reddit link, where someone says it's absolutely fine since it only affects video switching.

Which is it?

Is 12V needed for video blanking?

Or is it only needed to switch the aspect mode?!

You could leave the 12v system in place and go with a resistor load. That's what I do. I'm using a 1k 3 watt resistor. Since you're using SCART it would be the safest way to go.
https://en.m.wikipedia.org/wiki/SCART
(pin 8 & 16)

Some Dreamcast SCART cables use +5v instead of +12v. That's the disparity and confusion why some work and others won't when the +12v system is removed.

Fucking hell!

I was about 2 minutes away from desoldering the 12V and bricking my console, when I thought: let me check DC Talk on my phone. And lo and behold - I see a diagram explaining all!

Thanks for the help.

This irritates the shit out of me - I am literally enraged due to all the incorrect nonsense I've seen online.

When notmorezombies on that Reddit thread said:

It wouldn't stop it from working, SCART uses a range of voltages on pin 8 to indicate status and aspect ratio to the display/input device. In my case even if the 12V regulator was disconnected everything would still work. You should be fine.

He was basically bullshit lying. Classic internet.

If I cut the 12V hardline I'm losing V-blanking and my TV will run the signal as if it's composite.

Who are these forum users who say ebverything is fine when quite blatantly it is NOT fine. Not even remotely fine.

No one mentions pin 16. Everyone is all like: "pin 8 is meaningless just cut the 12v". Bullshit. Cut the 12v and you lose pin 16, meaning you lose RGB meaning you end up with composite. Which is trash.

Thank you for that diagram. As I say, I was minutes away from bricking this thing. God fucking damn it! I dodged a bullet there. >_<

Now, can someone link me to a website that has a PicoPSU actually in stock? I need to do this the right way.

EDIT:

Ordered this:
https://kaicolabs.com/product/dream-psu ... placement/

Hope it works. Lots of reports say it bricks consoles. Lots of customers say they've used theirs for years.

i will just put it out there for anyone thinking about doing this and hasnt. i have a clone gdemu, and have run it for hours at a time. Never had a heating issue, and I dont have any other mods other than the coin cell battery mod.

Since this has segued into the heat discussion, I'll repost the only physical measurements I've seen anyone take of the temperature pre-GDEMU, w/ GDEMU, and w/ 12v regulator removed:

From Greg Collins aka Laserbear:
https://twitter.com/collingall/status/1 ... 82176?s=09
https://twitter.com/collingall/status/1 ... 46720?s=09
https://twitter.com/collingall/status/1 ... 99776?s=09

That was enough to convince me it was the right thing to do for my NTSC-U Dreamcast.

I'm gonna try another approach soon . I found on eBay a power supply made for medical use that actually fits inside the Dreamcast without almost any mod and it's 220v direct so you don't need an external power supply. It has all all the lines the Dreamcast needs and it's overrated for the Dreamcast . This power supply is cheap , and very efficient , built with today's technologies so it should stay cool without the drawing on 12v line . I'll let you know .