Bacteria's project - Modding a GP2x....FINISHED

Negative_Creep · Post by **Negative_Creep** » Tue Jan 15, 2008 10:23 am

Ah thanks for the infomation, I see now, it doesn't sound that big now, in the picture the gp2x mobo just looked tiny compared to everything else, I also like the "colouring" idea as it turned out really well on your PDA.

Good luck

bacteria · Post by **bacteria** » Tue Jan 15, 2008 4:57 pm

Thanks!

The GP2x mobo is quite small, as you see in comparison against a C cell battery.

The finish on this system will look miles better than on the PDA project I did and will look (should look) polished in appearance. I am hoping to make a stylish casing this time.

I may have some time tomorrow for the project, not sure yet. Next job is to get the audio working, it is all wired up but I didn't attach a ground wire from the GP2x to the PSone mobo, so that is probably why the audio is mute at the moment (audio needs ground). I had wanted to keep the TV-out cable intact, but decided to cut the three wires from the TV-out and connect the video lines to the PSone wires as having the S-video plugs are too thick for this casing and will stop the screen rotation.

The GP2x also has a quirk of running audio from the speakers on the GP2x as well as the TV at the same time (shouldn't but it does), I wired from the speaker wires from the GP2x to the audio input on the PSone screen (as I did on previous projects) - if that doesn't work, I will use the other two cables from the TV-out (left audio, right audio), if I don't need them I can just cut these TV-out wires and hot glue them to the perspex to keep them out of the way, and use them to help tidy the other wires in the system.

Lots of work to do yet, and lots of testing; definitely!

bacteria · Post by **bacteria** » Thu Jan 17, 2008 3:23 pm

I'll be able to do a posting or two tomorrow.

I decided to make the video cable longer and more flexible so therefore cut open the video cable from the GP2x TV-out cable. Easy enough. I did however come across a problem:

There are 4 cables to an S-video cable: luma, luma ground, chroma, chroma ground. Fine. I had previously opened up an S-video cable extension, had my 4 wires, great. I thought I would therefore open the GP2x cable and just extend the wires, like for like. Not fine.

Using my multimeter, I tested the GP2x S-video wires; the black and green cables were the luma and chroma wires, the red wire was ground (can't remember which), and the loose wires around which I had expected to be the other ground wire, wasn't - it was however ground for the external part of the S-video plug but not the connectors. The two grounds are separate. I therefore couldn't just extend the cables as I had first hoped as the PSone screen did not boot up; so I had to use a male and female S-video plug connected, and extend the 4 wires from the side to the GP2x and the 4 wires from the side of the PSone screen. Then all was fine. Only thing is that while I have enough room in the case for two fat S-video plugs, I wanted to make the connections neater.

What is that all about

Anyone know?

I had two batteries with slightly loose cables which were bugging me before, so I pressed a small strip of mounting board covered on one side by hot glue, onto the desoldering braid on the battery. This did the trick, and was far easier than my previous attempt with electrical tape. This method was so simple I wished I had done it before! The connections on the other batteries seem fine, so no point adjusting these unless the contacts fail.

I also spent more time making the wiring neater and as much of it away from the middle area of the project as possible.

kasar · Post by **kasar** » Thu Jan 17, 2008 4:21 pm

awesome mod bacteria. I liked it

I like a lot also the plastic glue near the solder places (on this photo: here ), nice idea!,I think I will use the glue idea also on some circuit board.

nice work

bacteria · Post by **bacteria** » Fri Jan 18, 2008 2:44 am

Thanks kasar for your comments. Pleased you like my work.

Soldering to such tiny points is fiddly, and whilst they will stay in place, even a reasonably small movement with the wire can make it break free; if the power is on to the mobo the wire could rotate and make contact with other components and short the system. Hot glue stops the wire moving, so removes the issue.

I know people say use flux when soldering to these connections, however I manage to do it without; I heat up my 30w soldering iron, get a small bead of solder on the tip and touch the contact on the mobo. After one or two attempts I can get a tiny amount of solder sticking onto the mobo contact place, I then make sure I have a little extra solder on a tinned wire, put that in place, and touch it (in position) with the soldering iron to make it bond with the small solder on the contact on the mobo. This needs a very steady hand. You only need to do this on one of the contacts for a button area as the other side is always ground (the same one for all contacts). It is wise after getting the wire connected to test with multimeter that you haven't accidentally encroached onto the ground contact with your soldered wire, if you have, use a craft knife or very small screwdriver to scrape the residue off; carefully; then retest, and when the two contacts are independent, you are ok. Then you can hot glue the wire to somewhere safe to stop the wire moving about. Hot glue is great, apply some as per the pic and you can pretty well bend the wire in any direction and it stays in place!

bacteria · Post by **bacteria** » Fri Jan 18, 2008 5:39 am

Screen pics of Psycho Pinball for the MegaDrive running below. It isn't easy to take pics indoors and get accurate colours, these aren't too bad.

As mentioned before, please ignore the paper tape and bits of perspex (especially the one on the right of the pic) stopping the screen area falling out when the system is upside down; a necessary thing at the moment.

I wired the joystick (just placed on top for the pic) with the up and down reversed - will need to fix that!

When the batteries got to about 7.4v, the screen started to flicker a lot (indicating batteries getting low). I need to recharge them sometime at the weekend so they are ready for when I resume the project on Monday.

I incorporated the recharger plug, made a hole in the case, hot glued the PSone female plug inside the case and wired it up (red arrow). When the on/off switch is off, the batteries voltage still run through the off contact (pink arrow), so I connected the positive terminals to the recharge plug (yellow arrows) and the negative from the battery contact.

I used the male plug from the PSone PSU I used before for the MP3 player (pink arrow) and wired it to the terminals on my recharger. Logic is when the on/off switch is on, power is off from the recharger so if left in by mistake, it doesn't matter. If the on/off switch is off, then the PSone plug gets connected to the battery so can recharge. Also, as the switch is dual polarity, when in recharge mode, there is no power going to the Ti card; ideal.

I really hope that I can get good playtime with freshly charged batteries, I will be happy with 5+ hours. I will be disappointed if I don't get good playtime as I opted for heavy C-cells. If playtime is poor, I will have to resort to just using the system on mains, which will be a shame. Time will tell, after testing is done next week.

The TV-out from the GP2x is fine, perfectly acceptable; TV-out from the GP2x is not perfect, fortunately the PSone screen is 320x240 (640x480 interpolated) as is the output from the GP2x, so this helps things.

One thing though; I will need to experiment with the audio levels, the volume controls on the GP2x seem more dominant than those of the PSone screen. I don't know at this stage if it is better leaving the PSone volume to mid range and controlling the volume level from the GP2x volume control contacts or not. I will need to experiment in due course.

I also need to experiment more with the D-pad joystick to see if it feels right in practice, if it doesn't I will replace it with a NES D-pad. Lots of testing and work to do yet, in other words.

kasar · Post by **kasar** » Fri Jan 18, 2008 11:36 am

hey thanks you for the great reply, you gave me a lot of ideas to fix my projects. as I can see it have a lot of wiring stuff inside, but it also still very clean and you have a lot of photos with great quality and a lot of info on the posts, nice job.

-post edited by kasar-

bacteria · Post by **bacteria** » Fri Jan 18, 2008 5:03 pm

kasar - That isn't a headphone jack I used for the recharge plug, it is the female plug from the PSone screen power in jack, so it is the right component, designed for the purpose!

Thanks for your comments.

kasar · Post by **kasar** » Fri Jan 18, 2008 5:13 pm

bacteria wrote:kasar - That isn't a headphone jack I used for the recharge plug, it is the female plug from the PSone screen power in jack, so it is the right component, designed for the purpose!

Thanks for your comments.

oops, srry I though it was when I saw the photo at first time , but now I checked it again (yes, I can see it now clearly near the red cross), then everything is perfect

hehe ...

bacteria · Post by **bacteria** » Sun Jan 20, 2008 11:26 pm

These batteries are proving annoying. Before I installed them I testing soldering to the battery terminals of an AAA cell and did it easily, however I couldn't make solder stick to C cells, so I used desoldering braid on the centre of the contacts and wrapped them tightly in electrical tape to maintain the contact. Problem is, as it transpires, that any flex of the perspex on my case at all, and the braid can move a little and disconnect the current from the cells. This is not acceptable. I tried to recharge my battery pack, all was fine for an hour or so, then suddenly the contact was lost yet again.

The solution (as I didn't get batteries with solderable tabs at the time) is to use the small strip of mounting board with hot glue, and press it onto the desoldering braid directly on the battery terminals; as this gives a good bond, keeps the protection on the battery for air bubbles to be released (if happen during recharging process) and only needs a fairly small surface area so is not affected by any case movements at all. I did this on some of the battery terminals, I will have to do it for all of them now, as when I fix one part, I get a problem elsewhere. This has been a learning curve and a quest to find a reliable and simple solution (which I have). I just hope I haven't caused any damage to the system during the recharge before and the fluctuating power my system has been getting (I will know later in the morning when I get to test the system).

First job now is to get the battery terminal connections reliable and strong, I will then post a pic of what my solution looks like. Subject to my system not being fried, I will have this solution cracked.

bacteria · Post by **bacteria** » Mon Jan 21, 2008 4:54 am

Ok, this looks butt-ugly and messy, but the batteries are making proper connection now, and the GP2x and PSone screen boot up nicely. It doesn't matter however if the guts of the system look ugly, they will be invisible under the outer shell anyway when done.

I tried soldering to the batteries directly - works fine on alkaline cells, even an alkaline C cell, however for some reason these rechargeables proved to be very awkward indeed; solder didn't stick and the surface area which I tried this on stopped being conductive! Fortunately, I did this on the negative end of a battery, so I still had half the cell surface to make contact with. Weird I had this difference between rechargeable and alkaline cells.

Some of the batteries I secured in by folding some desoldering braid and putting hot glue onto a strip of mounting board and pressing it down until it dried. Some of the batteries refused to play ball, so I put a nut against the braid and used stronger electrical tape (the red stuff in the pic) to apply the pressure; the tape goes around the cell a bit to keep it taught. One or two of the cells worked best with wire wrapped around a nut, secured in place with the tape and the wire soldered to the electrical wire.

I had to use different techniques because the batteries are all hot glued in place and I have more space to do work on some that others; so space dictated the method I needed to use, and which method worked fine - if it worked one way, sense to leave it be, if not, I tried a different method on it.

Next time I will endeavour to use batteries with solderable tabs! It will save me lots of hassle. If I can't get solderable tabs I will have to mount the batteries in cases and use them that way. The issues I have had with these cells has taken a lot of time to resolve and been a real pain; however I have them, they cost me about Â£35 ($70) so I intended to use them!!

The system is currently plugged into my recharger. The light is on red, which means it is recharging. The recharger I am using came with a couple of adapters, I had to strip the wires from one of them to join onto the PSone male connector.

The recharger can recharge at either 500mA or 1000mA and 2, 4, 5, 6, 7, 8 or 10 cells at a time; so I have set it to 6 cells at 1000mA to see how it gets on. (If you have 6 cells, that is 6, if you have 2 sets of 6 cells in parallel, that is still classed as 6 cells according to the manual - that makes this recharger very useful indeed).

Anyway, off to sleep now, came off night shift and have another one tonight, so I need sleep now. When I wake up in a few hours' time, the cells should be fully charged. I am hoping all goes well on the charging process!

vskid · Post by **vskid** » Mon Jan 21, 2008 9:28 am

What is the wattage of your soldering iron, and did you try using flux? A higher wattage iron will heat the area faster instead of letting it seep into the component. Flux will clean the area and help heat transfer. I'll try using flux later on, and tell you what happens. I've been hoping to use your idea so I can give my PSP a 6 AA battery pack, but my tests without flux failed.

bacteria · Post by **bacteria** » Mon Jan 21, 2008 10:27 am

I use a 30w iron, it gets pretty hot. It was just a cheap one I got off e-bay, pencil tip end, works fine (done on my work to date on all my projects with it). I went to Maplins a few days ago but they ran out of flux, so I bought a flux pen off e-bay yesterday, awaiting it to arrive. It will be useful for soldering to traces on mobos; the only thing I can't solder to at the moment as I can't get the solder to stick otherwise.

As mentioned, I can easily get solder to stick on alkaline battery contacts, for some reason rechargeables resist, and when you take off the coating from part of the surface area it no longer conducts so you need to use an untreated area. WFT? I guess this means that you might get a wire soldered to the contacts with using flux, but if you succeed, your connection is dead!

If you come to the same findings, vskid, you might need to resort to what I had to to improvise something to make it work (ie something metal and big enough to apply pressure to a wire on the contact, like a small nut or screw); else use a couple of sets of battery compartments designed for AA cells and link them up.

UPDATE:

Recharger worked fine, I am getting 8.52v out of the 6 cells now. No idea how long the charging took, somewhere between 5-8 hours.

You always get a drop in voltage with NiMH cells a while after they have been left a while after recharge, after about 18 hours they are at about 8.21v.

bacteria · Post by **bacteria** » Tue Jan 22, 2008 8:46 am

I wanted to see how the screen rotation would be in practice and whether it worked or not, so I gave it a try. I removed the strips of plastic from the front and hot glued four strips of perspex to secure the circle in place, mimic having a case front and be better to work with:

As you see below, there is plenty of room to put my hand on the circle to rotate it (by friction). The PSone screen is under the perspex so it can't get marked or easily damaged.

Taking it carefully, very carefully! Half way there...

...and done. I now need to open the system up and see what, if any issues there were with doing this.

It proves the concept works, however the PSone screen, PSone mobo, having about 3mm or so between the PSone mobo and the perspex protector, the perspex protector (2mm), the GP2x mobo thickness and wiring and the TV-out plug thickness brings it very close to the 30mm I have to play with for the overall height of the system. I will see if there is anything I can relocate (wiring wise) or hot glue to trim, to give as much gap between the rotating screen and GP2x mobo as I can, to give a smooth rotation of the screen.

Anyway, proves concept works. It has been an interesting project so far!

project_failure · Post by **project_failure** » Tue Jan 22, 2008 7:20 pm

Nice work so far! I was wondering how well the rotating screen was going to turn out and it seems to work fine.