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View Full Version : Will a Sinclair SPectrum PSU frazzle my Genesis or are they lenient?



XDanger
May 13th, 2009, 03:30 PM
Game Gear is supposedly quite forgiving in its power requirements but what about the Sega Genesis?

I'm using a Sinclair Spectrum brick on one of mine at the moment and it seems fine, No smoke coming out of it.

Will I shorten its lifespan like this?

UK Megadrive likes 10v 1.2A

Spectrum PSU is 9v 1.85A

carlsson
May 13th, 2009, 10:00 PM
I'm using a switched, universal DC adapter with my Megadrive. It also delivers 9V, up to 2A or so. There is bound to be a voltage regulator inside the unit, so 9V or 10V should not matter. However I'm not sure the ZX Spectrum PSU is stabilised. If not, unloaded it could deliver up to 14V or so. Whether this affects your application I can't tell, cause the Megadrive will probably charge (?) as much load as a ZX Spectrum would.

NathanAllan
May 14th, 2009, 08:04 AM
If it will power the game gear, then it ought to work on the Genesis. Not the first model, but the second one. The polarity is different between them, and the plugs are different sizes.

The model 2 is smaller, and it ought to work. The Genesis does have power reguilation on the inside, it can handle anywhere from 9-12 volts and still work.

IF it is the larger model, it will not work, like I said the polarity is switched. You'll get a power light on and a black screen.

Nathan

XDanger
May 14th, 2009, 12:30 PM
I have the old type Mega Drive which is center neg polarity ,I'm assuming the sinclair power supply is the same since it works but cant see anything on the brick to indicate.

I know 9v is ok but I'm more worried about the 1.84A doing damage.


I know bo about electrickery

Sorry to confuse about the Game Gear (which I don't have) I just thought I'd mention it since its also a sega machine and shares some attributes with the Genesis/Megadrive

This is kind of a power supply 101 question but like I say ,I don't know diddly./

barythrin
May 14th, 2009, 12:39 PM
The recent peak in Sega/vintage gaming posts are an interesting addition to the use of the board :-) Kind of cool and something I haven't dabbled that much with so neat to see a few folks stand out. That's all, not too useful of a comment but wanted to say I'm enjoying the threads ;-)

cosam
May 14th, 2009, 12:44 PM
I know 9v is ok but I'm more worried about the 1.84A doing damage.
Power supplies are rated for the maximum they can supply, so you can run anything up to 1.84A. No worries there.

The Spectrum adapter is unregulated; not sure whether the original Mega Drive/Genesis unit is regulated or not. It shouldn't matter too much - as pointed out, it has its own internal regulators anyway.

carlsson
May 14th, 2009, 01:55 PM
Yes, it is more dangerous to use an undersized power supply, something you will suck out every watt it can produce until it cracks up. Generally power adapters are specified to deliver more power than the unit normally uses, and probably this is true for the Megadrive too. In any case 10 * 1.2 = 12W while 9 * 1.85 = 16W, using the formula P=U*I.

Dreamcast270mhz
May 14th, 2009, 04:45 PM
Yeah i've used every thinkable power adapter for my Genesis CDX 8v-12v usually, so I'd say you'd be fine. As for my Genesis 1(larger model) I've only used a 3-in-1 black power bow and the adapter supplied.

XDanger
May 14th, 2009, 09:43 PM
9 * 1.85 = 16W

But it should be ok right?

Thankyou

carlsson
May 14th, 2009, 10:07 PM
Yes, as I briefly mentioned my universal DC adapter is supposed to deliver up to 9 * 2 = 18W if I recall correctly, might be 9 * 1.5 = 13.5W though. It is a bit like a PC power supply, the larger effect the beefier stuff you can connect to it. If your 350W PSU breaks down and you find a good deal on a 500W with the same connectors, you don't hesitate because it might be too powerful for you old PC.

BG101
May 15th, 2009, 09:23 AM
As a general rule, as long as the power supply is capable of supplying enough current, it's the voltage that matters. If the device you're powering has its own regulator inside (as has been suggested) then a few extra volts shouldn't do any harm but a higher input voltage will result in more current being drawn (and can burn out the regulators if it's too high).

Switch-mode regulators tend to be more tolerant and will actually draw less current at higher voltages, but that's another matter.

The device will draw as much current as it needs, you could connect a PSU capable of delivering 20 amps to it and it will still only draw 1.2A. A bit like connecting a table lamp to a 16A socket ;)


BG

XDanger
May 15th, 2009, 10:45 AM
This is good news and thankyou very much. :D

I've just noticed the power supply from my x-rocker gaming chair (that I never use) also has 10v 1200mA, No idea of the polarity though.

XDanger
May 23rd, 2009, 04:37 AM
Today I found a Mastersystem center neg. supply but its only 500mA

NathanAllan
May 23rd, 2009, 06:45 AM
Power supplies are rated for the maximum they can supply, so you can run anything up to 1.84A. No worries there.

The Spectrum adapter is unregulated; not sure whether the original Mega Drive/Genesis unit is regulated or not. It shouldn't matter too much - as pointed out, it has its own internal regulators anyway.

Genesis/MD have regulation on the inside of the console, so it can be used. Lately I have been repairing a lot of these things, they're pretty fragile it turns out. I always upgrade the diodes in them, and put a fuse in when I can.

I got these really neat self-healing fuses, look like disc capacitors. A lot of these game systems don't have any kind of fuse on the inside and takes out the regulator chip when there's a spike. Got two broken Master Systems with that being the likely culprit. They'll be getting fused, too.

Xdanger, that 500mA power supply sounds like it's for a Master System II, the original one is the same rating as the Genny/MD.

Power and Gaming, toss in Batteries and it becomes my favorite subject(s)!

XDanger
May 23rd, 2009, 12:32 PM
Yup MS-II

NOW Ive found a 9v 850mAMP center negative polarity Sega model no.3084

Whats that for?

Google isnt giving me much but I may be doing the internet wrong...

Another MSII supply?
__________________
If somebody wants to swap I'll give them 3 to 1 :) (not really the postage would be too much)

carlsson
May 24th, 2009, 10:27 AM
Perhaps it is for the Mega-CD 1?

NathanAllan
May 24th, 2009, 01:29 PM
My guess would be for the Mega CD 2, the first one needs more current.

XDanger
May 24th, 2009, 10:38 PM
Yeah Mega CD1 is the same supply as MD1 I think.

I'm going hunting again today (for retro stuff) hopefully I'll find something.

XDanger
May 31st, 2009, 01:41 PM
I GOT ONE!!! :)

And a boxed Phillips G7000 ,Not tried it yet.

Starshadow
June 11th, 2009, 11:53 PM
Lately I have been repairing a lot of these things, they're pretty fragile it turns out

I found the Genesis to be one of the most durable systems out there. Most I ever had to do to one was spray contact cleaner into the cart slot.

NathanAllan
June 12th, 2009, 09:02 PM
I found the Genesis to be one of the most durable systems out there. Most I ever had to do to one was spray contact cleaner into the cart slot.
The console is very durable, yes, I was referring to the power supply. I think this is why they're so cheap-- so many are still out there from when they were new. Most other consoles have all had to be repaired.

Come to think of it, the Genesis is so far the **only** console that has not had to be repaired so far by me! 2600 needed switches, NES needs the cart slot and clip the stupid leg of the lockout chip, 7800 needed ports and power receptacle fixed, Dreamcast needed a fan (another needs the whole gd-rom), SNES needed a new back panel (probably abuse, though, no fault of the console). I have a Sega CD that needs a good lube job, but another that is perfect.

Seems the Genesis might outlive pretty much all of them, esp the new ones.

Starshadow
June 12th, 2009, 10:00 PM
I once tried to do an Internal Speaker Mod to a Type 1, problem is the headphone jack can barely power a 2 incher. Maybe next time I get a Spare Type 1, I'll put a Gameboy Speaker in it.

I was mostly doing this so it could be used with an Apple II color composite monitor and still have sound without adding external speakers.

XDanger
June 14th, 2009, 01:09 PM
what contact cleaner?

Starshadow
June 14th, 2009, 02:35 PM
I use the Radio Shack stuff, just be sure its not the Cleaner/Tuner Lube :onfire: