Friend's Genesis (Model 1, 1601) Died

[Blu]

Hi Racketboy Gang!

I have a random question here that I'm asking for some help on.

My friend's Sega Genesis died a while ago, back in 2020, and he's particularly attached to it because it's his wife's original console. Here's some quick context that I gathered from him:

"So here's what happened. When I got the Genesis it had no power adapter, but I read online that a Famicom power brick would work. I plugged it in and it did.

This was 2010 or so, and I don't know if you remember, but retro gaming advice wasn't as robust. I didn't realize that it's different amps and volts and the repercussions.

So I used it in the Genesis for years. About 10 years (and I didn't play it all the time. Maybe a few times a year, then not as frequently.

Then in 2020 right as the pandemic was starting I was playing Shinobi III and then Sonic 3 and it just shut off.

That's when I did research and found retro gaming advice online was a lot better. What I gathered is that the Famicom power brick (maybe?) didn't supply the power the Genesis needed so that it had to work harder. Plus I was playing two games that also require more of the Genesis.

Since then, I bought an OEM Genesis power brick for the Model 1. It does not power on and the indicator light doesn't come on. But the heat sink gets HOT! Ridiculously hot! So something is happening.

I did a little test with a Multimeter but I honestly forget now what the conclusion was, and realized I needed a pro."

Here's the power bricks he was using:
Sega Model 1602-3
Famicom: HVC-002 (AC100V, 18VA, DC10V, 850mA)
And the Genesis Model 1 specs from a power standpoint: DC9V 1.2A

Does anyone have any suggestions here? Ziggy was really helpful and pointed me in the right direction. Would this be a simple repair, such as what Ziggy suggested: a repair to the joints on the power jack input on the board?

Similarly, does anyone typically handle these types of repairs and might want to take a crack at it? I know Genesis' are fairly plentiful, but I get the sentimental attachment given the history of my friend's console. So I wouldn't flat out suggest just replacing the board, etc.

Thanks all!

[Ziggy]

Ah, OK, with that story it sounds a little less likely that it's broken solder joints on the power input jack. Still worth checking, thought. It's an easy thing to visual confirm, and all you need is a #2 Phillips head screwdriver, and we can rule it in or out.

The first thing I would do is test the power adapter with a multimeter. It sounds like your friend already did that at some point, but cannot recall the readings. Well, ask him to do it again! The Famicom adapter, if good, will probably ready around 15v through the multimeter. This is definitely the first step in the repair though, because it's the easiest thing to do and it will point the problem to either the power adapter or the console. If the power adapter is reading below what you would expect, or no reading at all, then we can assume it's a dead power adapter. But if it's reading normally, then we can assume the problem is on the console side.

[Blu]

Updates!

He was able to run some tests with his multimeter. Set to Voltage 200 (lowest AC on his meter), and moved the meter to the soldering points on the power jack.
The Famicom power brick got 12 volts.
The Genesis power brick got 18 volts.

The Famicom (console) for certain works with the AC adapter.

Additionally, here's a photo of the Genesis power jack.

We're not certain if those are bad solder points.

[Limewater]

I haven't disassembled a Genesis before, but the next thing I would look for would be the voltage regulator.

There should be a 7805 voltage regulator close to the power jack. You'll probably find it by following that wire pair coming off the jack. It has three pins. If you have the unit plugged in and the power switch in the "on" position, you can carefully check the voltage between pins. The part should actually have a "7805" on it somewhere. You can google search for example pictures.

The center pin is ground.

Between one edge pin and the center pin you should measure your input voltage.
Between the other edge pin and the center pin you should measure 5 volts.

Be very careful not to accidentally touch two pins simultaneously with a single probe. You aren't risking death, but you could further damage the console.

[Blu]

Thanks Limewater!

Here's some updates for you based on the triage steps you provided.

He tested the voltage regulators, setting the multimeter to DC 20 volts. Then these were his readings:

Left regulator:
Input: 6.14
Output 4.21

Right regulator:
Input: 6.21
Output: 0.16

His thoughts are, "If I did it right, the readings are not what I expected. The input is low and the output is even lower. I'm glad unregulated voltage isn't spilling to the Genesis, but does this mean it's all escaping into the heat sink? That would explain why it gets so hot.

In any case, it seems like replacing these voltage regulators is worth a try.

[Ziggy]

Although it's not impossible, I'm always skeptical when I see something like this. As in, BOTH regulators happened to die at the same time? Instead of just blindly replacing the regulators, I would inspect any components that sit between the DC input jack and the regulator's input. There shouldn't be many components, if any. There's probably one capacitor that sits between voltage and ground immediately before and after the regulator. You may have to remove that heatsink, but you should be able to visually follow the traces leading to/from the regulators. Check visually for anything that is obviously damaged. And you can also use the multimeter to check for continuity and shorts.

I'm not sure what multimeter your friend has, it may or may not have a continuity setting. You can see in this picture what the continuity symbol looks like, among other symbols. If there's no continuity setting, you can just use a resistance setting. The continuity settings will make an audible beep when something is connected between the two probes. But if you have to use a resistance setting, there will be no beep, you'll have to look at the screen and note the reading. Continuity will be a reading of 0, or very close to it.

Anyways, you can check for shorts using the continuity setting. Be sure the console is powered off, unplugged, and press the power button a few times to discharge any voltage built up in caps (this is always good practice no matter what you're working on). Using the continuity setting, touch one probe to the middle pin of the regulator and another probe to each of the other two pins. You can do this for both regulators. And I would check for shorts between any capacitors immediately before and after the regulators. I would also check for continuity for all of the traces leading up to the regulators, something may not be visually bad but may be acting up.

[hidden0]

If power jack is fine , there is a power IC on a model one which can die as well as Bad switch can cause an issue as well when it doesnmt make a proper connection when u turn it on and gives low inpit voltages like in your case its 6v it should be 9v in order for the voltage regulators to work properly and provide 5v to the console.

So first check the on switch as well as power jack if both are fine , it can be the power ic , regulators don’t die like that according to my experience.

[Ziggy]

Nice tips, I was unaware the model 1 had an IC in the power regulator section. Do you know the model number of this IC ?

Checking the switch is easy using the continuity setting as I described above. You can see in the pics you posted, there's two wires running from the DC input jack to the power switch. Those two pins on the little DC input jack PCB, you can check those for continuity. When the switch is in the off position there should be NO connection between those two pins. When the switch is on, there should be a dead short (0 ohms). If there's any suspected issue with the switch, you can try cleaning it. Flood the switch with isopropyl alcohol or electrical contact cleaner, and then press the switch many times. The idea is that the alcohol will penetrate the switch, and by pressing the switch a bunch of times you are sort of scrubbing the contacts inside. Wait for it to fully dry before testing again.

[Limewater]

I'm with the other guys. Look at the switch first. My suggestion to look at the power regulators still more about trying to localize the problem than jump right to a solution.

[Ziggy]

I'm with the other guys. Look at the switch first. My suggestion to look at the power regulators still more about trying to localize the problem than jump right to a solution.

Oh, I agree. After ruling out the power adapter and broken solder joints at the power input jack, checking the regulators would be the next thing I would do too.

Also, not sure why I didn't mention this before... But as hidden0 pointed out, the voltage is much too low on the input pins of the regulators. So that points to a problem before the regulators. Since the power adapter and input jack was ruled out, the problem must exist between that and the regulators. There can't be many components that exist there, so it shouldn't be too hard to narrow it down from this.