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I bought a Sega Mark III from a seller on Ebay. It appears to be working in the pictures provided, however when I plugged it in at home, it did not work. No red LED light turned on. It was turned on their photos.

My question is, do I need some kind of transformer to get this thing to work in the US? It was the only thing the seller suggested, and I could not think of anything myself.

The power adapter is the one that comes with the console.

Thank you for any assistance.

what it says on the power adapter? 220v or 110v?

The mark 3 uses the same PSU as master system, that is 9v center negative 5.5x2.1mm barrel connector.

http://www.firebrandx.com/triads.html

A Japanese PSU should work just fine in the USA as long as the PSU says 100-120v (any number in that range is fine). The only wildcard is that eastern Japan and western Japan use different frequency voltages. Part of the country uses 50hz and part uses 60hz electricity (I'm only talking about electricity here not display rates). These days the PSUs support both but it's possible back in the 80s there were separate supplies for different parts of the country, or possible you got an aftermarket PSU or something

Anyway if you have a genesis MK2, a Famicom, av Famicom, super Famicom or super Famicom jr, coregrafx, TurboGrafx, master system, Sega CD, or gamegear, you can use the PSU from those with a mark 3 as they are all the same. I do recommend at least 1amp on the psu

The adapter that came with the system is 100 v. I will try a voltage transformer first. But if that doesn't work, I might have to return it.

It’s a simple AC to DC adaptor that matches many available ones that you may already own. It’s not worth using a step down transformer just for this.

When I first read the post (and after confusing up with down), I felt like 100v vs. 110v, whats the difference, but a little light googling revealed JP to US 100 to 110 transformers are a thing. Still seems like a long shot (my money's on a faulty mkiii unit) but worth a try I guess!
Edit: re-reading I see Maxim's point is you might have something just lying around which can provide what you need. Do just be careful to get the output polarity right.

I guess for a linear transformer it could technically produce an output voltage that's slightly too high? Or is there potentially a fuse in the transformer that might have coincidentally blown? Have you checked the output with a multimeter?

There's a voltage regulator in the console that regulates 5V. They're rated to handle up to 18V. If you use an 18V the only real difference is the voltage regulator will run a bit hotter. However, most of the wall warts rated for 12V might actually say 16V without a load.

I don't think the step down transformers make any difference in this situation. I know it does with LaserDisc players imported from Japan. Honestly, you could wire up an adapter to run this thing off a car battery. :D

Thank you all for the replies. I will receive a voltage converter on Friday and report the results back. I do not have any other plugs just lying around anymore. They are all long gone to the recycling center.

I would actually use this instead of using a bulky voltage converter and a 30+ year old PSU: https://console5.com/store/9v-1300ma-ul-certified-power-supply-transformer-for-sega-genesis-cd-nes-aes-tg16-100v-240v.html

I have one of these and it works great.

Unfortunately, the transformer did not help the situation.

If it's not powering on, there's a good chance the 7805 regulator is blown, which isn't all that uncommon given that there isn't much in the way of input protection on the Mark III. Thankfully it's a super common and cheap part and it's not too difficult to replace.

The seller said that I might have short circuited the system by plugging it in without using a transformer. Somehow I seriously doubt that at this point.

100VAC transformers (if they are the big heavy kind that actually have a literal transformer inside) can overheat and cook themselves quickly if supplied 120VAC. ... but not instantly.

If you have any other power supply of the correct voltage polarity that would be a good thing to test with.

I'm with Apolloboy on this one. It's likely the 7805 is cooked. The part is literally 50 cents and takes about 20 minutes to swap it out if you have some basic soldering skills. You can get them on amazon or Digikey, Mouser, etc. I'd say Radioshack but there are none left.

There's also the possibility that the power switch itself is broken. Have you tested continuity of the power switch? From there you should be able to test voltage going in and out of the 7805. If voltage goes in and nothing comes out then something is wrong with it or the traces around it.

OK, I will try to replace that component, and I bought another AC adapter. It seems like it will be easy enough to replace. Another question, or I can start another topic. I need a replacement reset button. However I don't have a 3D printer or anything like that. Where could I possibly get one?

Syxx573 wrote

OK, I will try to replace that component, and I bought another AC adapter. It seems like it will be easy enough to replace. Another question, or I can start another topic. I need a replacement reset button. However I don't have a 3D printer or anything like that. Where could I possibly get one?

As far as I know, there is no aftermarket so you'll have to have someone design and 3d print one.

Author	Message
Syxx573 Joined: 04 Oct 2023 Posts: 8	Sega Mark III, US user Posted: Wed Oct 04, 2023 2:27 am
Syxx573 Joined: 04 Oct 2023 Posts: 8	I bought a Sega Mark III from a seller on Ebay. It appears to be working in the pictures provided, however when I plugged it in at home, it did not work. No red LED light turned on. It was turned on their photos. My question is, do I need some kind of transformer to get this thing to work in the US? It was the only thing the seller suggested, and I could not think of anything myself. The power adapter is the one that comes with the console. Thank you for any assistance.

sverx Joined: 05 Sep 2013 Posts: 3828 Location: Stockholm, Sweden	Posted: Wed Oct 04, 2023 7:40 am
	what it says on the power adapter? 220v or 110v?

Lifeisasimulation Joined: 30 Sep 2023 Posts: 16	Posted: Wed Oct 04, 2023 8:09 am
Lifeisasimulation Joined: 30 Sep 2023 Posts: 16	The mark 3 uses the same PSU as master system, that is 9v center negative 5.5x2.1mm barrel connector. http://www.firebrandx.com/triads.html A Japanese PSU should work just fine in the USA as long as the PSU says 100-120v (any number in that range is fine). The only wildcard is that eastern Japan and western Japan use different frequency voltages. Part of the country uses 50hz and part uses 60hz electricity (I'm only talking about electricity here not display rates). These days the PSUs support both but it's possible back in the 80s there were separate supplies for different parts of the country, or possible you got an aftermarket PSU or something Anyway if you have a genesis MK2, a Famicom, av Famicom, super Famicom or super Famicom jr, coregrafx, TurboGrafx, master system, Sega CD, or gamegear, you can use the PSU from those with a mark 3 as they are all the same. I do recommend at least 1amp on the psu

Syxx573 Joined: 04 Oct 2023 Posts: 8	Posted: Wed Oct 04, 2023 12:15 pm
Syxx573 Joined: 04 Oct 2023 Posts: 8	The adapter that came with the system is 100 v. I will try a voltage transformer first. But if that doesn't work, I might have to return it.

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Wed Oct 04, 2023 5:58 pm
	It’s a simple AC to DC adaptor that matches many available ones that you may already own. It’s not worth using a step down transformer just for this.

willbritton Joined: 06 Mar 2022 Posts: 671 Location: London, UK	Posted: Wed Oct 04, 2023 6:21 pm
	When I first read the post (and after confusing up with down), I felt like 100v vs. 110v, whats the difference, but a little light googling revealed JP to US 100 to 110 transformers are a thing. Still seems like a long shot (my money's on a faulty mkiii unit) but worth a try I guess! Edit: re-reading I see Maxim's point is you might have something just lying around which can provide what you need. Do just be careful to get the output polarity right. I guess for a linear transformer it could technically produce an output voltage that's slightly too high? Or is there potentially a fuse in the transformer that might have coincidentally blown? Have you checked the output with a multimeter?

Maraakate Joined: 05 Jun 2010 Posts: 757 Location: Pennsylvania, USA	Posted: Wed Oct 04, 2023 8:42 pm
	There's a voltage regulator in the console that regulates 5V. They're rated to handle up to 18V. If you use an 18V the only real difference is the voltage regulator will run a bit hotter. However, most of the wall warts rated for 12V might actually say 16V without a load. I don't think the step down transformers make any difference in this situation. I know it does with LaserDisc players imported from Japan. Honestly, you could wire up an adapter to run this thing off a car battery. :D

Syxx573 Joined: 04 Oct 2023 Posts: 8	Posted: Thu Oct 05, 2023 2:11 am
Syxx573 Joined: 04 Oct 2023 Posts: 8	Thank you all for the replies. I will receive a voltage converter on Friday and report the results back. I do not have any other plugs just lying around anymore. They are all long gone to the recycling center.

ApolloBoy Joined: 30 Jan 2007 Posts: 317 Location: San Jose, CA	Posted: Fri Oct 06, 2023 7:18 am
	I would actually use this instead of using a bulky voltage converter and a 30+ year old PSU: https://console5.com/store/9v-1300ma-ul-certified-power-supply-transformer-for-sega-genesis-cd-nes-aes-tg16-100v-240v.html I have one of these and it works great.

Syxx573 Joined: 04 Oct 2023 Posts: 8	Posted: Sat Oct 07, 2023 2:40 am
Syxx573 Joined: 04 Oct 2023 Posts: 8	Unfortunately, the transformer did not help the situation.

ApolloBoy Joined: 30 Jan 2007 Posts: 317 Location: San Jose, CA	Posted: Sat Oct 07, 2023 5:02 am
	If it's not powering on, there's a good chance the 7805 regulator is blown, which isn't all that uncommon given that there isn't much in the way of input protection on the Mark III. Thankfully it's a super common and cheap part and it's not too difficult to replace.

Syxx573 Joined: 04 Oct 2023 Posts: 8	Posted: Sat Oct 07, 2023 12:04 pm
Syxx573 Joined: 04 Oct 2023 Posts: 8	The seller said that I might have short circuited the system by plugging it in without using a transformer. Somehow I seriously doubt that at this point.

lidnariq Joined: 24 Mar 2021 Posts: 120	Posted: Sat Oct 07, 2023 6:15 pm
lidnariq Joined: 24 Mar 2021 Posts: 120	100VAC transformers (if they are the big heavy kind that actually have a literal transformer inside) can overheat and cook themselves quickly if supplied 120VAC. ... but not instantly. If you have any other power supply of the correct voltage polarity that would be a good thing to test with.

Maraakate Joined: 05 Jun 2010 Posts: 757 Location: Pennsylvania, USA	Posted: Sun Oct 08, 2023 12:33 pm
	I'm with Apolloboy on this one. It's likely the 7805 is cooked. The part is literally 50 cents and takes about 20 minutes to swap it out if you have some basic soldering skills. You can get them on amazon or Digikey, Mouser, etc. I'd say Radioshack but there are none left. There's also the possibility that the power switch itself is broken. Have you tested continuity of the power switch? From there you should be able to test voltage going in and out of the 7805. If voltage goes in and nothing comes out then something is wrong with it or the traces around it.

Syxx573 Joined: 04 Oct 2023 Posts: 8	Posted: Tue Oct 10, 2023 7:05 am
Syxx573 Joined: 04 Oct 2023 Posts: 8	OK, I will try to replace that component, and I bought another AC adapter. It seems like it will be easy enough to replace. Another question, or I can start another topic. I need a replacement reset button. However I don't have a 3D printer or anything like that. Where could I possibly get one?

Maraakate Joined: 05 Jun 2010 Posts: 757 Location: Pennsylvania, USA	Posted: Tue Oct 10, 2023 2:43 pm
	Syxx573 wrote OK, I will try to replace that component, and I bought another AC adapter. It seems like it will be easy enough to replace. Another question, or I can start another topic. I need a replacement reset button. However I don't have a 3D printer or anything like that. Where could I possibly get one? As far as I know, there is no aftermarket so you'll have to have someone design and 3d print one.

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