Faulty Guitar Hero Guitar – multiple button presses (disassembly)

Posted on May 4, 2016 by Gareth

A friend recently picked up a 2nd hand Guitar Hero guitar. It worked mostly well, but at times when pressing some of the frets, other frets would also register. This makes playing the games normally a nightmare, as you’re currently being penalised for mistakes you didn’t actually make.

I took it apart but couldn’t find much wrong with it, besides some odd design decisions. /start side rant

There are 5 buttons on the fretboard. So if I were to design it, I would have 6 wires, 1 for each button, and one ground. But the fretboard has 8 connectors. I’m not sure if it allows a wire to be damaged and it to continue to work, but it doesn’t seem so. All I can think is that they had 8 pin connectors, and decided to use them. On the guitar itself, the 8 pins connect to a small PCB, with 6 lines coming from it straight to the microcontroller. It confuses me.

/end side rant

I didn’t have any way to test the guitar, so I gave it back, but my friend returned saying it seemed slightly worse. This was concerning. I got him to return it to me so I could take another look, this time requesting the receiver dongle as well so I could do testing myself.

USB Guitar Hero Dongle

The USB receiver is detected by Windows, and shows up as a game controller, so it’s quite easy to test the response of the system. What I found is that when the red button was depressed, the yellow button would trigger for a few 100ms as well. And likewise when depressing the yellow button, the red button would also be triggered for a few 100ms.

Windows sees the Guitar Hero as a gamepad, allowing one to monitor the inputs.

So again I opened up the guitar, spent some time with a multi-meter probing around, but didn’t find much. The connection from the buttons to the microcontroller all seemed to be in order, without any obvious problems. I don’t know what the problem actually was. The soldering on the board was relatively poor in my opinion, quite a bit of splatter, and several potentially joined lines. I took a scalpel to the board and cleared off any extra residue and solder I noted. Plugged everything back in and it all appears to be functioning 100%.

Main PCB, some solder contamination noted.

Again, I don’t know what was/is actually wrong with the board. Time will tell if the problem reoccurs, but at the moment it seems to be working well.

Disassembly
The guitar is fairly straightforward to disassemble. The fretboard pops out and is secured by multiple Torx-screws, and inside the PCB is secured by the same screws.

Screws to loosen to open fretboard

Two screws holding PCB in place. Slight press-fit.

The body of the guitar is similarly assembled. Remove the face plate and loosen all the screws on the back (11 in total, one is hidden behind a ‘warranty void’ sticker). Take care when separating, as the whammy bar needs to be threaded through, and some wires connect the two halves of the guitar together (namely the battery connector), these can be unplugged fairly easily.

Location of screws to loosen to open guitar body

The main PCB is secured by screws which can be easily removed to give access to the board.

Location of various items within the guitar body

Remington F4790 Partial disassembly

Posted on October 13, 2015 by Gareth

Recently the foil on my Remington F4790 got a hole in it, it makes the foil and cutter part of the razor unusable. While I placed replacement foils on order, I figured I’d just use the trimmer, but then trimmer stopped working.

Apologies for the poor image quality, they’re screengrabs from a video.

The foil and the cutters pop straight off with a little bit of a pull. Thereafter there are two small screws at the hinge point which can be loosened.
The foil and cutter head then comes out. Take care when reassembling to align the pop-out with the slot on the head.

From here there are 4 screws easily accessible that can be loosened.

A black rubber seal is then visible, which comes off easily to reveal two white plastic mechanisms which are driven by a motor. Align the drive shaft (1) on the motor so that the point is away from the trimmer. Plastic mechanism [2] can come straight off. Plastic mechanism [3] drives the trimmer and has a shaft going down. It can now be lifted out.There’s a round rubber seal between the trimmer and the motor housing which must be removed. The trimmer must now be fully extended. With a bit of jiggling the trimmer will come out completely. There is a metal spring near the bottom which might catch, see below.The trimmer is unfortunately a sealed mechanism. The outer casing is two parts which look like they clipped into each other, but looks like some heat was used to ‘seal’ it. Anyway, I pried it apart, because there was nothing left to do. Not too much seemed to break.

When I opened it up it was clogged up with hair preventing it from moving. I cleared all of it up, and the cover fortunately managed to clip back together and seemed to hold.I don’t really know how to disassemble the razor further. There are two screws visible, but loosening them doesn’t achieve anything. Through the clear motor housing other screws can be seen connecting it to the outer case, but no way to access them.

I think the outer case is all just clipped together, but felt nervous in forcing it apart when I still want to use the razor. If my foils don’t make it in the post, then maybe I’ll do it, but for now I can’t see any further way to take the razor apart besides forcing the outer casing apart.

Chromecast – first thoughts

Posted on September 16, 2015 by Gareth

A friend got his hands on a Chromecast recently, but due to some technical restrictions was unable to use it, as such he lent it to me to give it a twirl. A Chromecast has been on my wishlist for quite a while. I really like the idea of the product, but the I haven’t been able to warrant the price of buying one when I have a PS3 plugged into my TV which will accomplish most of the things I want a Chromecast for.

Setup was a cinch. Plug the Chromecast into an HDMI port and a USB port on your TV and it’s set up its own wi-fi hotspot. I installed the Chromecast app on my Android phone and connected directly to the Chromecast. Then used that connection to get my Chromecast onto my home wi-fi, after that I was good to go, or so I thought.

First thing I wanted to do was play music from my phone onto the TV. Open my default music app (Samsung Music) and continually press the ‘cast’ button, but am unable to find any devices. Realise this isn’t a Chrome’cast’ icon but a Samsung feature. Decide to try Google Music instead. Surely. First I had to re-enable it. Can’t find a ‘cast’ icon. Update Google Music, still can’t find a ‘cast’ icon.

Samsung Music App

After much Googling, still can’t find out why my ‘cast’ icon isn’t showing, but find out that it will anyway only allow you to play music in your Google Music cloud, of which mine is empty. Give up. Open Youtube app, works perfectly. Youtube takes a bit longer to open on the Chromecast itself than what I’d like, but after its loaded it works fairly well.

After a while I found the LocalCast app. Install that and am finally able to play music from my phone onto the Chromecast. However the free version has horrendous advert implementation. After a few songs a video ad would start playing on my phone, and at the end of the advert the music would stop casting to the TV, this happened on several occasions.

Give up and try Soundcloud app. This worked fairly well, however after listening for a while, when the next song would come on, it would first play on my phone speaker for 10s before jumping over to the Chromecast, slightly annoying. I eventually gave-up on the phone and started playing with Chrome on my PC.

I installed the browser’s Chromecast extension and connected to my Chromecast. Amongst other things this lets you cast your browser tab to the TV. This worked very well. I ended up playing individual podcasts and Soundcloud from my browser to the TV.

I then installed the recommended Videostream extension. From this I managed to watch videos on my TV. This worked relatively well, although depending on the file format, I could watch flawless 720p video, or get buffering issues on a 360p clip. A bit annoying; maybe my wi-fi is partially to blame.

Overall I love the product, the apps however need some work. A lot of work. Maybe I didn’t try hard enough, maybe I should have tried out one of the paid for apps, but I really expected it to be better supported by Google application and extensions. I still don’t have a nice way to play music from my phone or computer in a nice library format.

In any case, I gave the Chromecast back. It’s still on my wishlist, and if there’s a massive sale I might buy one, but not at the R650 Takealot is asking.

New backwards compatible USB cable

Posted on May 2, 2015 by Gareth

Why hasn’t there been a USB cable developed that is reversible like Apple’s lightning connector? This is something that has bothered me for a while. There are a lot of jokes around the USB connector, my favourite being this one from SMBC.

But why can’t we have a reversible one. So I did a speed run through the 56 MB of documentation on USB 2.0, and can’t see any specific reason that this can’t be done. The only reason I’ve come up with is that there is a risk of shorting, especially if someone doesn’t conform to the standard. I also read on StackExchange, one person’s answer relating to USB specifications that the USB logo must be displayed on the top of the connector, something I feel can be easily overcome.

I have seen a prototype demonstrated before, and while nice, I don’t think it’s the simplest solution to the problem. I believe this solution makes use of a similar mechanism. Also I really feel a plug shouldn’t have moving parts.

So that leaves us with this:

I decided to test out Sketchup, having being spoilt with student version’s of Autodesk software throughout university, it was something new to try out. So excuse the poor animation and model.

In any case, I took an old USB cable and shaved off the casing to test out the feasibility of this option. And my initial thought played true. If you have contacts on both sides of the plug, on the side not connecting to the USB port, the contacts short with the springs in the port housing, which in practice would result in an overload warning from your computer, and the USB port shutting down.

So, I can see why no one has done this yet, but I still think there’s a better solution than what we currently have. And I’m not convinced that my method, with some minor adjustments, can’t work.

Some funny things I found in the standards document include maximum insertion and extraction forces, of 35 N at 12.5mm/min and 10 N at 12.5mm/min respectively. Also a cable pull-out specification, because who is going to try grip a plug, when you can just tug on the wire :)

note: this post was started in June 2014, but I’ve only now made time to tie everything together and publish, in May 2015

Fiddlings

Gareth's Random Blog of Fiddlings

Category Archives: electronics

Faulty Guitar Hero Guitar – multiple button presses (disassembly)

Remington F4790 Partial disassembly

Chromecast – first thoughts

New backwards compatible USB cable