Found a Nomad today

8bitwizard · Post by **8bitwizard** » Sat Jul 21, 2007 1:23 am

Nomad, power supply, Sonic 2, extra controller, $7

But the plastic screen cover (not the display) is cracked. And the power jack is flaky, even after opening it up and resoldering the connector.

I'm seriously considering cramming a bunch of big electrolytic capacitors in there to give it more resistance to power dropouts.

Jorge Nuno · Post by **Jorge Nuno** » Sat Jul 21, 2007 1:53 am

Big Capacitors might be ok... but does the nomad has free space required for them?

The idea I have of portables is that everything is "super-packed" inside and i'm pretty sure thats the case with a nomad, so you might be in for a challenge, putting those caps inside...

I think it's better to replace the power connector on the console or on the cord or both hehe

8bitwizard · Post by **8bitwizard** » Sat Jul 21, 2007 3:08 am

Not much room, it seems. I had a 2200uf 10V which was just a little too tall (1cm diameter, 2.5cm tall) to replace an 820uf 6v on the board, and a 10000uf 16V which wouldn't fit anywhere (2cm diameter, 3.5cm tall).

But I found out that the capacitor for the power jack was a puny 100uf 25V crammed between the power jack and the power switch. The next size down that was on my work table was a 470uf 25V (about 1cm x 1cm), and I connected that with some extension wires.

It didn't seem to help much, so I got out a slot cleaner and the Nomad got a lot more reliable. Still, I could rotate the power plug and it would reset a lot (rather than lock up), so there is probably something about the design of the power adapter plug that causes problems with a handheld that it wouldn't with a fixed console.

It did flicker the battery low light without resetting a few times during the twisting, so maybe it helped a little bit. Now I can whack it with my finger in various places and Sonic and Tails keep playing in the attract mode.

I also put some clear tape on the inside of the cracked screen cover to help keep it flat. The screen was almost exactly as tall as my tape was wide, so there weren't any seams. I had to do it three times because I got too many bubbles and dust the first two times. It's still not perfect, but good enough.

I see someone selling replacement screen covers on ebay, 10 for $20+$5 shipping. I guess I should get some.

evildragon · Post by **evildragon** » Sat Jul 21, 2007 3:12 am

I wouldn't reccomend using a capacitor that is not specced for the where it's going..

I'm trying to fix my DX7 synth which has a bad cap only when warm, and it's causing major problems...

You want to match atleast the "capacity" (ph, uf).. and if possible, same voltage, or higher...

Jorge Nuno · Post by **Jorge Nuno** » Sat Jul 21, 2007 3:21 am

The batteries do their work as a Huge charged capacitor.

Those resets have to do with the duration of the drops:

small: nothing, tile corruption, lockups
medium++: resets

Try to connect the caps before the power gets down to 5V, so they drop from 10V which takes longer to reach shutdown voltage than drops from 5V

Jorge Nuno · Post by **Jorge Nuno** » Sat Jul 21, 2007 3:22 am

evildragon wrote:I wouldn't reccomend using a capacitor that is not specced for the where it's going..

I'm trying to fix my DX7 synth which has a bad cap only when warm, and it's causing major problems...

You want to match atleast the "capacity" (ph, uf).. and if possible, same voltage, or higher...

Since they are used for power filtering, the bigger the capacity, the better.

The voltage is just the breakdown voltage so anything superior to the max voltage the capacitor will get, will be fine too (this aplies to every capacitor)

For frequency filtering you have to replace with the same capacity, because changing the capacity will change the amplitude/phase over frequency range

Is it capacity or capacitance in EN? LOL

in PT-PT we say «capacity» in portuguese (capacidade)

evildragon · Post by **evildragon** » Sat Jul 21, 2007 5:03 am

to be honest, i don't know.. lol i read all sorts of books from all over the world, so i use both terms, capacitance, and capacity...

8bitwizard · Post by **8bitwizard** » Sat Jul 21, 2007 12:36 pm

Jorge Nuno wrote:The batteries do their work as a Huge charged capacitor.

What batteries? I said nothing about batteries. The Nomad is designed to work with no battery module attached. It just happens to be a little bit unreliable when used that way.

And the puny 100uf capacitor was as close to the input as I could get. The power goes through a diode to prevent reverse power from killing the unit, then the power switch, then the capacitor. It's possible that the 100uf was just meant for some filtering on the adaptor power and the 820uf is for after the 5V regulation. I didn't see an obvious 5V regulator like a 7805, but I didn't try hard to look for the regulator.

Jorge Nuno · Post by **Jorge Nuno** » Sat Jul 21, 2007 12:42 pm

Right, but I meant batteries, when someone runs a nomad from batteries, then plug it to the power outlet, without removing them...

In that case they prevent the power drops

8bitwizard · Post by **8bitwizard** » Sat Jul 21, 2007 12:43 pm

And the batteries are also heavy (either the rechargeable pack or AA pack) and this one didn't come with one anyhow.

Jorge Nuno · Post by **Jorge Nuno** » Sat Jul 21, 2007 12:47 pm

8bitwizard wrote: And the puny 100uf capacitor was as close to the input as I could get. The power goes through a diode to prevent reverse power from killing the unit, then the power switch, then the capacitor. It's possible that the 100uf was just meant for some filtering on the adaptor power and the 820uf is for after the 5V regulation. I didn't see an obvious 5V regulator like a 7805, but I didn't try hard to look for the regulator.

well you can rip out the 820uF put a bigger one in there an wire the positive lead to the input pin on the diode

Is there a L387A?
that's a low drop 5V reg

Or It could have a switching regultator (easy to notice beacuse of the coil+chip+diode)

TmEE co.(TM) · Post by **TmEE co.(TM)** » Sun Jul 22, 2007 6:49 pm

I recommend you to try caps used in cellphone batteries, these are small, and have enough capitance (I got 10V 2200µF from 5110 one... used in my S3 cart).