It Could Be That The Purpose Of Your Life Is Only To Serve As A Warning To Others (Epic Fail edition)

What I learned this weekend:

When disassembling a 3rd-generation iPod Nano for use in a homebrew marriage of iPod and amplifier...

...do NOT try to separate the logic board from the battery shield. I either torqued and damaged the logic board attempting this, or (more likely) it's an Apple design feature that the logic board be in contact with the shield for grounding or some such.

A better approach may* be to remove the battery from the shield, and Dremel the shield down a less-unwieldy size. Unless of course, there's some other Apple design feature that wants the battery in direct contact with the shield too... (note, I'm mounting this in a "heatsink" case, so I don't lack for places to mount the battery to deal with heat dissipation, once separate from the shield). Back to the intartubez for another broken iPod, I suppose.


*I have not actually tested this "better approach", so it's only potentially better at the moment.

FrankenPod (a/k/a GaragePod)

What would you do with the following?

1 - 8GB iPod Nano (3rd-gen), broken

1 - iPod charging dock, with remote

1 - USB car charger

1 - Dayton DTA-2 T-amp module

Well, if you're me, and the ancient stereo receiver you've pressed into duty in your garage is starting to deteriorate, you think, "I have an idea!"

So you add:

2 - Dual Binding Post

1 - 2.1mm Panel-mount DC jack

1 - Penn-Elcom Heatsink Box

1 - Penn-Elcom Endplate (more on this in a minute)

1 - SPST Small Rocker Switch with Red Illumination 12VDC

1 - Round Red-Insert Control Knob

1 - Panel-mount USB A Female jack (scavenged from an old PC slot-mount USB pigtail, but Jameco carries it)

And you start to plan.

First off, I chose the heatsink box as an enclosure because it looks kinda rugged and cool. I only bought one endplate because I'm planning to use it as a template. Since this is destined to sit on the shelf in my garage and keep me company, I wanted it to have a kind of garage-y look to it, so my plan is to make at least the front plate (if not both) out of 1/4" wood stock. Of course, the binding posts are for the speakers, the DC jack is to accomodate a wall-wart for power, and the switch is for the power. Unlike the Podzuma and Cheapzuma, I'm not replacing the stock volume control, but I am planning to disable the on-off function of the stock pot, and put on a more attractive knob. I scrounged the USB jack from a motherboard-header-to-USB-A adapter that fits in a computer expansion slot, so it already had the wires broken out at the end of the cable.

You can't just use any old broken iPod for this. For that matter, it doesn't have to be broken, but broken ones are definitely cheaper on eBay. In this case, the iPod was broken in a very specific way: everything works except the clickwheel. It turns out that the connector between the logic board and the clickwheel had corroded (looked like moisture was the culprit). I tried replacing the clickwheel, but the tiny connector and ribbon cable were too small to clean effectively, so while I got it to work, it only ever worked intermittently. However, if you hook it to charging dock that has a remote control, it runs like a champ. This build will require me to remove the iPod innards from the original iPod case, so it's a good thing I don't have much invested in it.

You can generally find the sort of iPod dock I bought on eBay for a few dollars, like this one. Just search for "iPod dock remote" and a whole plethora of cheap crap out of China will pop up. Basically, what you're looking for (well, what I was looking for at any rate) is the USB charging/dock interface and the IR remote control. The nice thing about this one is that it boils down to two small circuit boards (each about 1/2" wide x 2" long), and if you were really desperate and/or skilled, you could get it down to one, since the second board is really just the breakout board for the ports.

Speaking of ports, I haven't decided yet if I'm going to make the video output available on the back panel of my rebox or not. Since it's a 3rd generate Nano, it will play video, but this is destined to be the stereo for my garage, and if I'm in the garage, I'm generally working, not watching video. On the other hand, knowing me like I do, this will probably see life beyond the garage at some point, so the output may come in handy.

Here's the notional block diagram for how everything should work. I'm planning to use the car charger as an easy way to get from the 12VDC that the T-Amp likes down to the 5VDC USB that the dock likes. Because I want to to be able to hook this to my computer and add new music from time to time, I'm going to extend the dock's USB jack to the back panel of the enclosure. I think that I can get away with just piggyback-splicing the external jack and the output of the charger to the input of the dock. I don't plan on using both connected at the same time (when it's in the garage, it'll be connected only to the power, when it's connected to the PC, the power cable will be unplugged) so as long as I keep the pinouts right, I should be good, particularly sincle I'm scavenging a bit of USB cable from the other jack on the surplus computer part. Beyond that, I'll short the power leads on the T-Amp's control umbilical to let the switch do its work, and probably just run a very short headphone patch cable from the iPod to the T-Amp and not fuss with desoldering and re-soldering the jacks.

Given that I've sourced the main components via eBay, I should consider calling this the PodBay, but then, I'd have to add some sort of access door to it, just so I could legitimately utter the phrase "Open the PodBay Door, please." Yes, I know. Professional help.

Cheapzuma Reborn - The Finished Product

Fresh off my success with the Podzuma rebuild, I decided to tackle rebuilding Cheapzuma. I wanted to take advantage of some of the things I'd learned with Podzuma (like the separate power switch), and I wanted to change the form factor a bit.

If you remember, the previous version of the Cheapzuma looked like:

The four OEM Ford speakers were each rated at 25W / 4 ohms, and becuase I was using a single T-Amp board to drive them, I had to wire them in series, effectively making each pair an 8-ohm speaker. The T-Amp can drive 15W into 4 ohms, but only 10W into 8 ohms. Since I wasn't really tremendously happy with the output of the first Cheapzuma (its primary design goal was cheap, not super-loud), I wanted to see about addressing that problem while I was already tearing the thing down.

Here's the front-on view of the finished product. I decided to go with a tall, narrow box, and arrange the speakers vertically, rather than the original 'X' layout. This makes for a more compact unit to drag to tournaments. The case on this rebuild is actually some 1/2" birch plywood I had leftover from a cabinet project I'd recently finished, and as is becoming my custom, the finish is Plasti-Dip.

Because I wanted to add some ooomph to the build, and having several T-Amp boards laying around, I decided to use two amp boards, and have each board drive a pair of the speakers. This allows each board to drive the speakers at 4 ohms. Instead of 2 channels at 10W per channel, I should end up with 4 channels at 15W per channel.

To accomplish this, I first decided I'd want an upgraded battery, so instead of the 5Ah SLA of the original plan, I picked up a 7Ah alarm batttery. From the power switch, I simply ran two sets of leads (one to each board) for power, and shorted the two red leads on each amp board to make them permanently "on".

Rather than try to deal with two volume controls, I also shorted the volume control leads on the amp boards, rigging them for full-volume output. On the connector, there are 2 red and 5 white wires. The red wires, as previously mentioned, are for the power switch. If you number the white wires 1 thru 5 (it doesn't matter which end you start from, as long as you're only counting the white wires), simply connect wire 1 to wire 5 and wire 2 to wire 4. Wire 3 is there to connect the ground plane to the factory potentiometer, and can be left alone. I used the same type of pot from my Podzuma rebuild in this one (50 Kohm, audio taper, dual gang), but wired it directly to the input jack on the top panel. From the pot, I simply ran two leads per channel to the amp board headphone inputs (making sure everything is also tied to the ground plane).

A quick bench test actually pointed out that I had a bad left channel in one of my recycled original Sonic Impact boards, but swapping in a Dayton DTA-2 fixed the issue, and I was able to verify that all of the speakers were being driven properly.

Instead of the Penn-Elcom steel dishes, I used the plastic tops of some Radio Shack project boxes I had. As with the Podzuma, I routed a slight relief to accomodate the lip of each cover, but I liked the way they looked sitting a bit proud of the case, so I didn't stress over really recessing them.

The bottom cover is the battery access, the tall, narrow cover is for access to the electronics, and the top cover is simply there to mount the controls. I left out the 12V-out jack (never really having used that feature on the Podzuma), but otherwise, the battery-charging circuit is the same as the original.

Finally, because I'd never encountered a situation where I'd used the original Cheapzuma without using the cheap Wal-Mart luggage dolly to roll it around, I decided to pick up some 3/4" pipe-mounting clamps and attach the new 'zuma permanently to the dolly. I used "Wall Dog" screws because they have a very large, aggressive thread which seemed like it would stand up to the normal jostling of transit better than standard wood screws.

As with the Podzuma rebuild, I'm insanely pleased with how this came out. The difference in output from the previous Cheapzuma is noticeable, although I still think the Podzuma (benefitting from being designed by a professional) has better performance, particularly on the low end.

Since it's loud and (relatively) cheap, I might have to start calling this one the Janicezuma (after Chandler's ex-girlfriend from the show Friends).

Podzuma Reborn - The Finished Product

I do still owe the world some construction pictures, but for now, here's the finished product for the rebuilt Poduma:

The case is made from 1/2" MDF. The finish is several coats of Plasti-Dip.

This is pretty much a standard Podzuma build, with the exception of the separate power switch, and replacement volume control. The volume control is a 50 Kohm audio-taper dual gang potentiometer. The power switch is a simple SPST switch with integrated 12V LED, which actually renders the super-bright blue LED power indicator somewhat redundant, but since I'd already drilled the dish, I can live with it. Everything else is as specified in the original build plans from PartsExpress. Since I'm using the separate power switch, I shorted across the red power leads on the T-Amp board.

I routed 1/16" reliefs for all of the dishes so they'd mount flush, and used T-nuts and machine screws (with the heads also coated in Plasti-Dip) to secure them, to make removing them easier.

With 4 heavy drivers and the MDF construction, this is definitely a weighty beast. I may try giving it some wheels or a cart for easy transport. The handle and case can definitely bear the load, but I certainly wouldn't want to have to carry it more than a few yards on a regular basis.

Construction photos soon.