Virgin Stock Turbo Duo Not Powering On ??

[Nec.Game.head]

I just recently scored on my very first US Turbo Duo in non working order. The previous owner told me it was already experiencing audio issues as a result of the old bad capacitors still being in the system. Besides that it work just fine. He that said he stored it away for a month or so and just recently when he decided to power it on to play some Bonks Adventure it did not work anymore. He passed it on as a gift to me with the agreement that I would do my absolute very best to get back up and running.

Here is what I have tried out so far. With my multimeter I tested out the AC adapter jack and it's receiving the 9 volts that the AC outputs. I tested out where the power cable connects from the AC power board to the motherboard and that checks out fine. I tested out what looks like a black fuse or something and that's passing the 9 volts. I tested out the fuse which physically looks fine and that dose not show a reading on my multimeter. I also tested out both of the 5 volt 7805 voltage regulators and they also do not show any readings on my multimeter. Not sure where to go from here. Should I replace the fuse that dose not look blown out or should I replace both of the 5 volt 7805 voltage regulators ?? Once I get her powered on the next thing will be recapping the motherboard.

[Fidde_se]

7805 has grund in the middle leg, one of the outer legs is in the other is out, check if there is anything going in and work yourself back to the DC plug, somewhere there your problem is luring.

[NightWolve]

If neither outer leg on the regulators showed any power (one would be 9-10+V, the other the regulated 5V) then your problem is further back. Good deal if you get this up and running and I should think so!

If there is 9 VDC before the fuse, but not after, then you've figured out your problem right there regardless of how it looks... Kind of a no brainer to replace that before doing something more difficult like replacing a possibly burned out regulator...

[Nec.Game.head]

Sweet tested out both 7805 voltage regulators on both out and ins, no power. Will go ahead and replace the fuse first and see if that is my issue to start off with. The reason I asked about the fuse was because I did some research and found a dude on Youtube that seemed to have the same problem as I do. He replaced the fuse first that was not passing power through and got no results from it. He never did put out a second video to show if he did in fact ever fix his Duo. Messaged him and haven't heard back from him either. Thanks I will go ahead and give it a shot to today.

[Fidde_se]

Just test the fuse for continuity, if it works then it's no need to replace it.

[Nec.Game.head]

Yep I tested out the fuse for continuity there is none. Gonna go buy a replacement later on today. Hopefully it'll be as simple as that. Excited to get this Duo back up and running properly !!

[Nec.Game.head]

If neither outer leg on the regulators showed any power (one would be 9-10+V, the other the regulated 5V) then your problem is further back. Good deal if you get this up and running and I should think so!

If there is 9 VDC before the fuse, but not after, then you've figured out your problem right there regardless of how it looks... Kind of a no brainer to replace that before doing something more difficult like replacing a possibly burned out regulator...

Well I went ahead and replaced the 3 amp fuse, tested it out with my multimeter and nothing no voltage passing through. I suppose the next thing to try out is replacing both 5 volt 7805 voltage regulators and see what happens then. If anyone else has any other suggestions I would greatly appreciate it.

[NightWolve]

Tangent: I swear, I'm gonna break this Android tablet of mine in half one day to force myself to buy a new one... I lost my previous post to this thread using the default browser it came with... It may be faster than Chrome, but sometimes it just closes out or redirects without warning or reason... The terrible speed and responsiveness just to type something up is beyond frustrating no matter what you're using... I WANT TO BREAK IT, I DO!!!!!! /rant

OK, nechead, pump the brakes on your eagerness to replace the regulators... If you didn't see 9-12 VDC on either leg of any of the regulators, and 5 VDC on the opposite leg, you've not established them as being the problem just yet...

From what I read, you verified that the 3 Amp fuse was blown, OK, that's a start. Something happened, a short, a surge, etc. that led to that and now possibly something is permanently damaged or it could be as simple as an open/cut trace line.

Do you still see 9-12 VDC anywhere on the motherboard ? The black thing you mentioned is a diode, do you see 9-12 VDC before it or the fuse, etc. ? You do say you have power after the choke I guess (the board you plug the wire in), and that means you don't have a short, because that would cause a voltage drop and possibly burn the fuse in your power supply.

Since you see 9-12 VDC on the motherboard somewhere, that kind of rules out a short, as I said, so I'm leaning towards an open/burned trace line or some component the power passes through having given up... You're seeing 0 VDC at the regulators, so stop suspecting them just yet...

Just work your way forward from the power input, and follow the flow of power to where it stops...


Pro Tip: If you manage to fix this, switch to a 1 to 1.5 Amp glass fuse. 3 Amps is WAY too much and risks permanent component damage to IC chips, memory, etc. I damaged one of the SRAM chips in my SNES because I ran out of 1.5 Amp fuses and kept burning them out, then used a 3 Amp one I had available, which burned out again, but this time I got graphics corrupting in certain games because of the damage!

I think Hudson made a mistake with using such a high-rated fuse for something that runs on 850 mA to 1000 mA... I made the recommendation to Desh for 1 Amp also, and that if it burns out again during the normal course of play to switch to 1.5 Amps which should be perfect. The SNES by default has a 1.5 Amp pico fuse soldered in place, so after it burns out you need to mod the area with 2 clips for switching to glass type fuses for easier replacement.

[Desh]

I think Hudson made a mistake with using such a high-rated fuse for something that runs on 850 mA to 1000 mA... I made the recommendation to Desh for 1 Amp also, and that if it burns out again during the normal course of play to switch to 1.5 Amps which should be perfect. The SNES by default has a 1.5 Amp pico fuse soldered in place, so after it burns out you need to mod the area with 2 clips for switching to glass type fuses for easier replacement.

Truth... and I haven't had any problems with it yet.  However, I also don't have hours and hours of continuous play time because I'm still diagnosing my non-functioning controller issue.  I will jump back into it once I receive the logic probe I ordered.

[Nec.Game.head]

Sweet thanks for all the useful info NightWolf. If at the end I can't figure it out, I'll be sending it out to one of the techs on here.

[NightWolve]

So no luck yet ? If you're reading full power up to the fuse, then the power switch, etc. yet nothing further down the path the power line travels in, it's getting cut off somewhere seems to me. Be sure to check again if the new fuse burned out after installing it BTW. The burned out regulator in my SNES showed the high voltage on one side, but no output on the other. I would also bet another breakdown scenario for it is it causes a short and hence voltage drop, so you'd read far less than the 9-12 VDC going in and maybe the fuse pops too. But anyhow, you're not seeing a voltage drop and you're seeing nothing on any leg at the regulators, so the high voltage is simply not getting there judging by what you said so far.