So this is a really easy mod that you can do in about an hour or less. I really like my old 80's Pioneer boombox and just wanted to make a little dock in it for my iPod without having to modify the actual boombox itself too much.
Since the cassette deck died on me long ago, I thought it would be an ideal space for my dock. If your cassette deck still works and you still use it, don't worry, this mod will not affect the operation of your cassette deck.
Stuff you'll need:
-3.5mm aux cable
-Cassette tape that you don't need anymore (the type that are screwed together are much easier to work with)
-Some adhesive Velcro
-Various screwdrivers depending on which ones your boombox needs for disassembly
-Soldering iron and solder
-heat shrink tubing
Step 1: Take apart your cassette tape and get it ready for your iPod
Unfortunately, I didn't take many photos of this project while I was building it. It was pretty easy though, and if you have any questions, feel free to ask!
Most cassette tapes will have 4 or 5 little Phillips screws on the back side. Take these screws out and separate the two halves of your tape. Remove all of the magnetic tape itself (you can just take the two reels out and all of the tape will come with it)
Then just trace an outline of the iPod you are going to use onto one half of the cassette and mark a spot to put a hole on the other half for your aux cable to snugly fit into.
Use a hobby knife or exacto knife to cut the plastic out where you outlined your iPod. This may take a little bit of work. Then just get a drill bit that is slightly smaller than the diameter of your aux cable's connector and drill out the hole you marked.
Step 2: Wire your aux cable
This is the only real mod you have to do to the boombox. Cut one end off of your aux cable and strip the wires. There should be a small red wire and a small white wire and each should be surrounded by some ground wire. Once you strip the ends, twist the two ground wires together.
Then unscrew the case of your boombox and separate the two halves. Most of these old boomboxes have an aux/line in somewhere. Once you have the case separated, find the backside of the aux L and R channels and solder your red and white wires to them and also solder the grounds that you twisted together to the ground on the backside also. Remember to use heat shrink also.
Step 3: Route your aux cable
Now just route your aux cable through the inside of the casing and have it come up through the bottom of the cassette deck. There is usually a fair bit of clearance in these old boomboxes, so space usually isn't really an issue. Once you've done that, you can screw your case back together.
Step 4: Cut some Velcro for your cassette tape and deck
Now you just need to cut some small strips of Velcro to stick to your tape and deck. You need 4 in all. 2 for the tape and 2 for the deck. You may want to find a different way for this step if you want to be able to use your cassette deck still. I can't guarantee that it won't affect tape play.
Step 5: Put your tape in and mount your iPod
Now all you have to do is put your cassette in with the aux cable coming through it and mount your iPod. Then when you switch your stereo to 'aux' function, your iPod will play through the speakers! I suggest blasting some Run DMC to celebrate. Then when it's time to put it away, pull the cable back out through your tape and stick it down in the area you fished it up through the deck and put your tape in the deck for easy transport!
I've entered this in the 'Vintage' contest, so if you like it, please vote!