Weekly How-To: Inside the Zoom 505 II Multi-effects

Ok, ok, it really hasn't been weekly, but I'm working on that. Time is limited over here, and I make the most of it when I can. Enough rambling and excuses from me, let's tear this baby apart!

What we're going to be doing today, is exploring the insides of the Zoom 505 II Multi-effects pedal. If you're interested in the history of this pedal, it can be found here (wikipedia entry) If you want one, they can be had on eBay for around $50, and around the same in your local used music equipment dealer's shop. Just a little bit about the unit before we start, it has 6 banks of 6 preprogrammed effects, for a total of 36 effects built in, that can be modified and saved using built in flash memory. It is powered by either 6VDC from 4 AA batteries, or 9VDC from an external power supply. On the back is the input jack, power supply jack, control in jack (more on that later) and output jack. Up top, you have the two footswitches, which are used to move between effects one by one, and if pressed simultaneously, activate the bypass and tuner. There's also the mod knob, which selects what part of the effect you are modifying, and finally the bank up/down switch, and a store switch right below it.







Time to tear it apart! One thing to make sure of, when you are messing with any electronic device, is make sure that it is not powered on, and if possible remove the power source. Although this device doesn't have any high voltage or dangerous components, it's still a good idea to remove power, so you don't fry anything while taking it apart.


The 505 II, like almost all guitar effects pedals, doesn't have an off switch, but is powered on when a cable is plugged into the input jack. Turn it over on it's back, and remove the 4 AA batteries if they are installed.


On the back, you'll immediately notice two screws right next to the battery door. Remove these, and look up near the top, right near the rear jack panel, you'll see two rubber pads. Pull these off, and remove the two screws that are below them. A good rule to go by when you are taking things apart, is to take pictures of where things go, and keep screws grouped together, either with a tray with compartments, or tape. In this case, all of the screws are the same, so it doesn't matter. Set them aside with the rubber pads.





Lift up on the metal plate, you can either pick it up from the battery compartment, or use a screwdriver to pry up a corner near the top. Either way, it should come right off with no problems.



Now we get our first look inside. Notice the two screws right near the battery compartment. Remove these and set them aside. Now, right under the screws, the battery terminals meet the board. Pry these up and out of the way. Be careful not to let them pop out of the battery compartment, they can be a pain to get back in, speaking from experience here! Up near the top of the board, there are two tabs that are holding the board in. Push them aside, and pick up on the board from the bottom part, near the battery connectors, and pull it out. Since the jacks are attached to the board, and stick out a bit near the top, you'll have to pull out and down to remove the board. Be careful of the ribbon cable attached to the board as well, it's not very fragile, but still use caution when removing it.















Lay the board on it's back, like shown in the picture. Now we can do some exploring, and see what makes this thing tick. First off, you'll notice that all of the buttons with the exception of the rotary switch, are just simple tactile switches. Also, the rotary switch just appears to be a potentiometer. Back to the main board, there are 10 ICs, along with two crystals, and a bunch of passive components.









The first IC has the markings PCM3006T, which a search on Alldatasheet.com reveals that this is a 16-bit, single-ended analog input/output stereo codec (DAC/ADC)



IC2 is a 2100 JRC, you can't tell in the picture since I suck at the photography. I couldn't find any information on it online.



IC3 is another JRC chip, this time a 7082B low voltage CMOS power amp



IC4 is a 29M33 voltage regulator



IC 5 is....IC5 is really freakin' small! It's a 4 pin SMD type package, and I can't make out any markings on it.



IC6 has the markings S93C5 6V02, which turns out to be a 2kb EEPROM. This is where all the custom settings are stored.


IC7 Ahh, now we get to the brains of the 505 II, at least one of them. This is one of their inhouse chips, with the markings ZOOM 505II 0001, which I'm guessing the 0001 is a revision number. I've only taken this one apart, so I don't know if there were any other chips in the series. 0017KP007 is also printed below the previous markings.




IC8 The other half of the brains, the ZFX2L chip, also made inhouse by Zoom.



IC9 is a fairly large chip, with the markings T14L256A TA22280. This one turns out to be a high speed CMOS static RAM chip.



And finally, the last one, IC10. IC10 is stamped with VHCU04, and it seems to be a hex inverter. What it's used for, your guess is as good as mine, but I think it might form some sort of bridge between the 505 II chip and the ZFX2L.



Now on to the board itself. A good deal of the components are SMD, though there are quite a few thru-hole caps, and one resistor. Also, the LED display is thru-hole, which is very important for the second part of this article, which will be published at a much later date, once I return to the states.

Some other things, as I was looking over the board, I noticed about 10 or so "test points", little gold pads at various places on the board. Some of them are labeled, VO-L and VO-R, which I think is an output test point, 512FS, 1FS, and 32FS. Not sure what these are for. The only other one that I can make any sense of is on pin 50 of the 505 II chip.

Near the bottom of the board it gets real interesting. There are two test pads, not included in the 10 I mentioned above, with one of them having a blob of solder covering it. They are labeled 505 II and 506 II. The Zoom 506 II is a bass effects processor. The question that comes to mind, is how different are the 505 II and the 506 II? There's a couple of empty places on the board, for various SMD capacitors, and there's one thru hole empty spot for a RF choke(I think) and a diode. I'll try and get my hands on a 506 II and see what the difference is. The 506 II seems to be a bit rarer than the 505 II, at least in my experience. If anyone has one they want to donate, or even just open up and take a few pictures, send me an email!




Well, that's about it for the Zoom 505 II tear down. If I ever get my hands on another one of these little buggers, I plan on playing around with it a bit more, maybe changing out the silicon diode for another one, and adding one in the open spot. As always, I hope you enjoyed the article as much as I did writing it. Any questions, comments or complaints can go to my email joshhoose@gmail.com or posted here as a comment.

Still working on new content....

Things have been pretty busy over here, so I haven't had a lot of free time to work on projects, but once I do, I have one or two that I'll post here. Until then, here's some pictures of my latest project, in it's beginning stages.









Right now, as you can see from the photos, all it does is go forwards when you plug a battery in. I have a fairly neat project in mind for it, once I get my replacement Freeduino board in and get it put together.

Upcoming content

I have a few ideas in mind for the site. The first is an ongoing weekly series of articles, one How-To and one do it yourself electronic project. Also, product reviews once or twice a month, and disassembling guides for something new once a month. In addition to all of that, I plan on maintaining a directory of links related to hacking, and electronics in general. I'm always going to be looking for ideas from my readers, so feel free to drop me a line at joshhoose@gmail.com or post comments here, I'll read them all!

Replacing the screen on a Dell Axim x51v (How to guide)

On my first how-to guide, I'm going to go over replacing a broken touchscreen (digitizer) for a Dell Axim x51v PDA. I'm fairly sure this will apply to the x51 as well, and maybe the x50 series, but don't quote me on that. As you can see in the first image below, I broke the digitizer, but the underlying LCD works just fine. Also notice the tools you will need in the picture. The Torx #5 and a small phillips screwdriver(not pictured) are a must, but the other tools, the dental pick and the opening tools are optional. The dental pick is used to remove the rubber pads on the bottom, and the opening too is (surprise, surprise) used to open the case. If you've ever worked on any of the various iPods, you'll notice that the two cases are fairly similar in how you open them. Also, a small razor blade or X-acto hobby knife will come in handy.

The first step is to choose a good place to work. You should have a large stable surface, with some place to ground yourself, and something to lay the PDA down on, in order to not scuff it up. Have all of your tools laid out within arms reach, there's nothing more annoying than having to search for a screwdriver halfway through a project!



Once your workplace is set up, turn the PDA off, flip the hold switch to the hold position, and remove any SD/CF cards and set them aside. Then, remove the battery cover, to do this flip the cover switch located right below the battery cover to the open position, remove the cover, and remove the battery by pulling up on the small cloth pull tab. Sometimes it's a bit stuck, but you're not going to hurt it by pulling it out.

Now that you have the battery removed, set it and the cover aside, and look for the four small rubber pads on the bottom of the PDA, in each of the four corners...shouldn't be too hard to find at all. Take the top ones off first, they are the easier ones. The bottom ones need a bit more work, since they actually go down inside the PDA a bit, this is where the dental pick really comes in handy. If you don't have one, you might be able to get by with a push pin or needle, whatever is handy. Once they are off, set them aside. I like to set them inside the cover (or on top of it, if you're using the expanded battery pack) the same way they were orientated on the PDA, it makes putting everything back together so much easier.



Look at the places where the four rubber pads were, and you should find four #5 Torx screws. Remove them, and place them with the pads, next to the pad they go under, once again, makes life easier when it's time to reassemble.







Ok, now we are at the fun part. The two halves of the case come apart, the black and the chrome are two seperate pieces. The place I ordered the replacement screen from sent two green opening tools, to help crack open the case. If you don't have them, there are a few ways to take it apart. One is to use a small flathead screwdriver, but you risk damaging componets on the inside. If you're a guitar player like myself, you probably have ten thousand picks laying around. Grab a thin to medium thickness pick and use that. You'll most likely mess up the pick at the end, but hey, picks are cheap! Look at the photos below to pick the easiest place to start opening the case. I started at the bottom by the charging connector, but that probably wasn't the brightest place to start. Up near the top, by the SD/CF card slot would be a much better choice, on the side away from the headphone connector.



Once you've loosened the top shell of the PDA from the bottom, carefully set it aside. Two notes of importance here. Be VERY careful with the microphone! The cable is threaded through a couple of little plastic notches, it is a very thin and flimsy cable, and easy to break, so make sure you're paying attention to it. Also, the buttons on the top side are not held in to the top shell by anything, so make sure you don't lose any of them.



The next step is to seperate the guts from the bottom of the shell. The only note of caution here is to be careful with the hold switch, and don't break it as you seperate the two parts. Set the bottom shell aside, and flip the PDA over on it's back (with the LCD facing down)



To remove the screen, you'll have to unhook the ribbon connectors from the mainboard. The problem with this is that the frame on the back that supports the CF card gets in the way, so you'll have to remove it. I didn't take a very good picture here, but there should be four phillips screws holding it on. Take them out, remove the frame and set it aside. I found it helpful to put the phillips screws back into the holes on the frame.



Almost there! Now look at the ribbon cable connectors on the mainboard. There is two of them that are attached to the screen. One is for the digitizer (the small, four conductor one) and the other one is for the LCD(the bigger one) Both need to be removed to replace the digitizer. For the small one, look for the two white tabs on the sides of the connector. Pry those out and away from the connector with a small screwdriver or your dental pick. It shouldn't be too hard to move them at all. Once it is out, pull the small ribbon cable out of the connector, and move on to the large LCD cable. Same thing, but the tabs are brown, and it's a bit harder to remove it. To remove the LCD ribbon cable, rock it back and forth gently while pulling on it. It's a bit harder to remove than the digitizer cable, but shouldn't be too hard at all. Once both cables are removed, pull them through the holes in the mainboard and remove the LCD/Digitizer unit.





Now the really hard part. If you're replacing the whole unit, you're done. Just replace it, and follow these steps backwards. If you're only replacing the digitizer, this is by far the hardest part of the entire project. You have to seperate the digitizer from the LCD. The problem? It's glued on to the frame! Use your razor blade to carefully cut through the adhesive that holds the two together. Make sure you don't scratch or cut the LCD while doing this! It is very fragile, and if you break it, instead of paying 10-15 dollars for a digitizer, you'll be spending $50 or more for a new LCD, so be careful! Trace around the edge of the screen to remove the digitizer, it's difficult, but you should soon get the hang of it.

Once you have the two apart, there should be enough adhesive left on the LCD frame to attach the new screen. If not, I'm not sure what you could use, maybe some thick superglue CAREFULLY applied to the edges. Rubber cement may work as well, but in my experence, I didn't have to use anything at all. Line up the digitizer with the LCD, and start doing all the steps backwards to reassemble the PDA. A few notes; be careful with the microphone, hold switch, buttons on the front bezel, and finally, the battery latch open switch. That last one got me twice! If your PDA refuses to power up after you reassemble it, take the back cover off again and make sure the switch on the board is lining up with the top of the switch on the back cover!



At this point, you SHOULD have a fully functional PDA. If not, retrace your steps, and make sure all cables are tight. Once I figured out the trick with getting the latch switch to line up, mine fired right back up. Now here's where I ran into my problem. The digitizer I picked up off of Ebay was the wrong one! The x51v apparently uses a slightly different digitizer than the x51, and x50. It's the same size, but the connector is on backwards, and will not work! Look at the pictures below, and make sure if you're getting a screen for the x51v, it has the connector that is on the left in the picture below, or it won't work! It'll fit, but won't work at all. I'm still waiting on my replacement, and as soon as I get it in, I'll take a few more detailed pictures that I should have taken towards the end of this guide.



I hope you found the guide useful. If you have any questions, comments, or if I totally assed something up, drop me a line at joshhoose@gmail.com or leave a comment here.

-Josh

Welcome!

Welcome to Hacks in Progress, my first blog. I intend this to be a place where myself, and other contributors can post accounts of their electronic projects, both finished, and still on the workbench. I will also be publishing reviews of whatever equipment I use, how-to guides for basic electronic and audio projects, and things I've learned as I experiment.

I should have some more content over the next few days, as I get things together and organize my thoughts and pictures into something somewhat coherent. If you have any ideas, would like to see something done here, or even become a contributer, drop me a line at joshhoose@gmail.com , or post here.

-Josh