Consider this an addendum to other iPod boombox mods. I admit I borrowed from other Instructables. Not to take away from those Instructables, here is a "shout out" to those that inspired me to dive into my own mod. Thank you.

Instructables on modding an old school cassette player boombox to play your iPod.
Aiwa boombox
JVC boombox
Phillips boombox
Sony boombox

Instructables on building a charger for your iPod.
Super Simple
Famous MintyBoost

These are all great Instructables. Unfortunately, I ran into some snags and wanted to add a few more features. So, my Instructable covers how I solved some of those problems. I hope this will help others who've run into similar snags or want similar features. Lastly, I had many "do-overs" with this mod and wanted to motivate other modders not to give up on their projects. If you have the courage to tear apart something you just modded, you'll end up with something you can be proud of.

I started with a Sony CDF-8, an old school combo cassette tape, CD, AM/FM radio boombox. What I wanted in the end is an integrated iPod docking cradle that would both recharge the iPod and play through the docking connector Audio Line Out. I wanted to add a compartment where the old tape mechanism resided. Lastly, I also have a Motorola SLVR L7 iTunes phone so I wanted to add an aux Line In jack.

I've broken this Instructable into segments based on the features I added and the things I learned. I've skipped over most of the basic stuff since the above Instructables do a great job of explaining all of that.

Sorry, I didn't write this Instructable for newbies. The details aren't included. I glossed over things assuming the reader had some previous modding experience. You'll note most of the photos I've included are after the fact. I didn't take any before photos since I wasn't planning to make an Instructable. Without the photos I couldn't include details needed for a neophyte to tackle this mod. Therefore this is more about Hints and Tips rather than a true step by step.
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Picture of HINT - HOW TO FIND A
In the other Instructables and various other places on the internet you'll read about problems with using what I call the "cassette-tape-head-method." You know, use the black, red and white wires on the tape head and feed the headphone output from your iPod to it. This doesn't always work and it didn't work with my mod either. One solution is to search the boombox main board for a left and right channel. If you're lucky, you'll find an "L" and "R" somewhere on the main board.

Here's a hint to make your hunt easier. Most of these boomboxes have a mechanical selector switch that switches the source from the CD player, radio or cassette tape to the main amplifier. Find this selector switch.

After you find the switch, flip the main board over and locate the correct pins for the cassette tape player. I was lucky, mine were labeled.

The switch is dual pole, one side for the left channel, the other for the right. Follow these traces to a spot where you can solder on some leads. Mine happened to end up on two jumper wires on the parts side of the main board which makes soldering real easy. On my mod, I wanted to run this "clean line" to both the iPod and an Aux. Line In. Therefore, I wired a pair of leads to this spot. Where do these leads terminate? One L&R pair can be soldered and heat shrunk to the 1/8 stereo line in jack, the other L&R pair to be wired to the iPod, See STEP 3.

Why is this line "clean?" Because it bypasses the cassette tape player's preamp and associated circuitry, which was designed for a tape head not the headphone output of an iPod. If you connect your iPod to these lines and adjust the iPod volume, chances are you'll get a much cleaner sound than using the "cassette-tape-head-method." Booya!


As mentioned in the background, one of the goals was to integrate an iPod docking cradle. Why not just buy one and mod it to fit? I use a case on my iPod and most off-the-shelf docking cradles require you to remove the case prior to docking it. Who wants to do that? I decided to build one from scratch that would fit into the boombox.

Parts required:
1/16" Acrylic sheet - Tap Plastic 2'x2' $7.00
Acrylic cement - Tap Plastic $3.40
1 iPod 30 pin Connector - Sparkfun http://www.sparkfun.com/commerce/categories.php - DEV-00704 $4.95
1 1/8" stereo jack - Radio Shack - 274-249 $2.99 Optional

Here's another hint. Buy the Sparkfun docking connector! In fact, don't buy the model I bought, they have a new one called the PodBreakout, DEV-08295, $14.95 which makes soldering these little buggers much easier. I mentioned "do-overs." I don't remember how many mistakes I made with this connector (DEV-00704). Several times I accidentally broke off the internal pins after installation. I ended up having to pull out pins from pins I knew I wasn't going to use to replace the ones I broke. By the way, if you do get model DEV-00704, I found it much easier to pull the pin out of the connector body, solder and heat shrink the wire and then replace it back into the body. There's less of a chance of soldering two adjacent pins together.

Don't think you can cut corners by using an iPod connector from one of those off brand iPod chargers. I bought two of these and found they only contain the pins for charging your iPod. They do not have the pins for the Left and Right Audio Line Out (pins 2, 3, 4). iPod Docking Connector Pinout Save yourself some heartache, just buy the Sparkfun docking connector...

At this point, pull out the cassette tape mechanism. Mine had four screws and two connectors. Now you have lots of space for a docking cradle.

The fabrication of the iPod docking cradle is straight forward. Basically, you are building a "box" out of 1/16" acrylic sheet. Find a location for the cradle. I have an iPod Nano 2G so even with its case, it was slim enough to fit where the mechanical cassette tape buttons used to be.

After you've chosen a suitable location, mock up the box in cardboard then transfer it to the acrylic sheet. Cut it out and glue it together using the acrylic glue. Cut a hole in the bottom so the docking connector will fit snugly in the hole. Glue this in place only after you're 100% sure all connections are working correctly, see below steps.

I had to grind down some plastic bits inside the boombox enclosure which wasn't easy because it was hard to get a big file into a tiny space. In the end, I used a cardboard nail file that was broken in half. A Dremel would have helped but I don't have one.

I also had enough room to install and On/Off switch (red button) and a stereo Line In jack (see STEP 4, below). Before gluing to the boombox you can spray paint it like I did.


Parts Needed:
2 Audio Isolation Transformers - Radio Shack Radio Shack - 273-1380 $2.99
Scrap of perfboard

Okay, here's the biggest hint of the entire mod. In STEP 1, I found a clean line. However, after I wired up the docking connector to test it, the Audio Line Out (Pins 2, 3, 4) Pinout signal was waaaaaay overdriven. I tested it with the headphone output and it sounded fine at about 1/2 iPod volume. However, the volume doesn't work when you use the Audio Line Out from the docking connector. The sound was absolutely gross. Back to the internet for some research I went.

On the internet I ran across some black magic called "impedance matching." Here's a link for some information. http://hyperphysics.phy-astr.gsu.edu/hbase/audio/imped.html Turns out, the Audio Line Out from the iPod is high impedance while the headphone output is low impedance. I figured the cassette tape circuit is designed for low impedance since it sounded fine with the headphone output connected. I needed to figure out how to lower the impedance of the iPod's Audio Line Out. I first tried to insert a simple headphone volume control in between the Audio Line Out and "clean line." All that did was made an overdriven signal less loud but still gross.

Then, I came across this device at DAK Industries. Impedance thingy It takes a low impedance circuit and matches it to a high impedance circuit via an isolation transformer. I wondered if I could reverse that principle.

Back to Radio Shack. I found these audio transformers and bought two of them (one for each channel). I used these "backwards."

I wired and heat shrunk the 8 ohm windings of the transformers to the "clean line" found in STEP 1. The bigger 1K ohm windings I connected to the docking connector (pins 2, 3, 4) Pinout. The grounds can be wired per the diagram. I mounted the transformers on an old piece of old perfboard. Then I modded one of the cassette mechanism brackets to mount the transformers. Lo and behold, the transformers worked! Booya!

Remember I was talking about do-overs? I finished up all the soldering, wiring and reassembled everything. I thought I was finished with the entire project. Not so! I powered up the boombox and eeeeeeeeeeeeeeeeeeeee - audio feedback! When I plugged in the iPod, the feedback disappeared. That meant I had a no load audio feedback loop. Doh! I wanted to drop kick the darn thing. Did I have the courage to tear it all apart to try to fix it? Not courageous, just stupid.

After taking it all apart again, I stripped off the shrink tubing, desoldered the connections and basically started all over. I reconnected it in different configurations. Nothing was working. Finally, I figured it out. Remember those two jumper wires I found on the main board, where I found the "clean lines?" I decided to cut them. Lo and behold, it worked! What I had done is cut out the preamp circuit. The circuit was causing a no load feedback loop.

In fact the sound was better than before. No hiss or humming, very clean. Booya!


One of the goals was to build in an iPod charger into the boombox. I figured this would be easy. Find a 5 volt line and connect it to pins 16 and 23 Pinout on the Sparkfun docking connector. Wham bam, done. Yeah right. Easy as the Manhattan Project.

Parts required:
1 push on/push off switch - Radio Shack - 275-617 $2.49
1 5V Fixed 7805 Regulator - Radio Shack - 276-1770 $1.59
1 10uf Capacitor - Radio Shack - 272-1025 $0.99
1 100uf Capacitor - Radio Shack - 272-1028 $1.29
1 Diode - Radio Shack - 276-1104 $0.89
2 50K ohm resistors - Mouser Mouser Industries - 270-49.9K-RC $0.11
2 75K ohm resistors - Mouser - 270-75K-RC $0.11
Scrap perfboard
heat shrink tubing

The first question is where to get the 5 volts. I decided to look at the circuit that drove the cassette tape motor. After ripping out the cassette tape mechanism, I fiddled with it trying to determine how it worked. Boy it looks complex!

The mechanism has many levers and springs but it is fairly simple. The play lever pushes down the tape head carriage and a reed switch that activates the audio and motor circuit.

Like Instructable Sony boombox I wanted the ability to turn on/off the iPod charging circuit. So I bought a Push On/Push Off switch at Radio Shack. It's the red button in the photos. I measured 10 volts on the motor circuit and confirmed that it turned off when the Stop cassette button was pushed (which disengaged the reed switch). Sure, there are many 5 volt circuits on the main board but those circuits did not sync on and off with the cassette tape audio circuit. Plus, the circuit connection was easy, since both the reed switch and the motor circuit were both routed through a single connector on the main board.

The next challenge was to convert the measured 10 volt to 5 volts. I started with this Instructable. Super Simple I searched the internet further and found this circuit and decided to use it. 5 Volt Regulator Build

Another trip to Radio Shack, a scrap of old perfboard, some soldering and blam, a regulated 5 volt source that could be used to recharge the iPod.

I used the connector that powered the motor and reed switch. I wired the output to the iPod docking connector (pins 16 and 23) Pinout.

I modified the cassette mechanism mounting bracket to hold the new 5 volt regulated charging circuit.

In STEP 3 I mentioned the "do-over". Well at that time, I found the iPod wasn't charging! It was getting the 5 volts but the iPod charging bolt would come on then disappear. That meant the iPod was running on battery while docked! Doh! Back to the internet for more research, I went. I found that newer iPod firmware requires a small voltage on pins 25 and 27 in order to charge. Why oh why!? Like I said, I wanted to drop kick the thing. Persistence yields perfection.

Hint - There is more than one way to charge an iPod. In STEP 2 I mentioned I bought two iPod chargers. I pulled out a VOM to analyze these chargers since I knew both of them actually charged my iPod. I found something interesting. One charger used an AA battery as a power source. The other used a wall wart. Both had different charging circuits. The battery powered charger used the typical 5 volt USB type power (pins 16 and 23). The wall wart version used the 12 volt Firewire circuit (pins 19/20 and 29/30). The Firewire version was more attractive, since it didn't require any additional components. Simply connect 12 volts to pins 19 and 29. However, I didn't have a 12 volt source on the main board. The power supply circuit of the boombox had only an output rated at nominal 9 volts. So I took apart the USB style charger and found a bunch of resistors configured in a simple voltage divider circuit.

These resistor (50K ohm, 75K ohm) values aren't available at Radio Shack so I ordered them from Mouser...and waited anxiously for UPS. After getting the four resistors I created a small subBoard.

I soldered and glued this board to the main charging circuit board and wired it up.

I tested and found it didn't charge! I jiggled the docking connector and found I mounted the docking connector too low. The charging circuit pins were not making good contact with the iPod. Doh! I had to break the glue bonds on the cradle (again) and reinsert the connector into the cradle. Success! It was finally charging.

Lastly, solder and heat shrink the connections to the red Push On/Off button that was mounted in the docking cradle in STEP 3. You use the wires that were connected to the reed switch mentioned earlier. Remember, that reed switch activated the audio circuit and the motor circuit (which now acts as an iPod charging circuit).

You should now have a docking cradle that charges your iPod and plays music through the boombox! Booya!


After I yanked out the cassette tape mechanism from the boombox, the cassette door didn't close. The door was spring loaded and the door latch was part of the mechanism. I could have glued the door shut but it seemed a waste of space. I decided to build a clear acrylic box and light the box from behind with a blue LED.

Parts Needed:
1 blue LED diode - Frys - 149mcd 3.8Vf @20mA
1 330 ohm resistor - Radio Shack - 271-1315 $0.99
some 28awg - 24awg wire
1/16" Acrylic sheet - Tap Plastic Tap Plastic 2'x2' $7.00
Acrylic cement Tap Plastic $3.40

First you need to cut away all the unnecessary plastic. On the cassette door, most of the plastic is used to hold the cassette tape in place. This is the fun part. With pliers, wire cutters, Exacto knife, saw and sandpaper, remove all plastic bits except for the hinge nubs and doorstop nubs.

I fabricated a spring loaded latching lever that holds the door shut. I stole a spring from the cassette tape mechanism.

On the boombox's front panel, cut away all the plastic but leave a piece of plastic that will act as an anchor to hold the door shut. Make rough measurements for a 5 sided box. Transfer these measurements to cardboard templates. Mock up a compartment in cardboard first. Make your mistakes on the cardboard templates. When satisfied, transfer the cardboard templates to the 1/16" clear acrylic sheet. Cut out the pieces. Fit one piece at a time taking time to trial fit over and over again. Start with the top piece, then fit the bottom, then the sides and the last part is the back piece. If you want a real professional looking installation, sand the exposed edges of the acrylic to a smooth finish using finer and finer grades of sandpaper. Use plastic polish (from Tap Plastics) to finish it off. Use acrylic cement for final assembly.

Now that I had a clear compartment, I had the idea to add a blue LED to light it up. I decided to power the LED with the motor circuit (9v) instead of the regulated 5 volt circuit I created. Why? I figured drawing more power from the motor circuit it would "help" the 7805 regulator. If I used the 5 volt side, it would have loaded the 7805 even more, causing it to heat up even further.

I bought a blue LED (specs. 3.8 Vf, 20 mA) at Fry's. Using this LED Calculator I came up with a 330ohm resistor, using the measured 10 volt motor circuit. The LED circuit is simple. Wire the resistor in series with the diode and use heat shrink on everything. Hot glue it to the inside of the boombox. Aim the light so that it will light up the compartment.

The final step is to simply zip tie all the loose wires for a neat appearance and reassemble the boombox. Booya! You're done! Feels good, doesn't it?

Final Shout Out - Kudos to all for contributing to this site! I never realized how much effort it took!
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Thanks for the comment. Umm, yes. The AM selector probably could be used instead of the tape. I got rid of my tapes long ago so I had no need for a tape player. Good idea though! Later! : )
smoak2 years ago
Could you rather than losing a tape player section, instead lose the AM station selection? So your selections would consist of cd/tape/fm/mp3?
aompes2 years ago
i have tried this project 5 years eariel then i give up the clean line search and i just plug the head reader of the tape and yeas the sound was noisy
then when i have read your instructubale i was happy that someone have success and give me hope so i opens the boombox ind i searh for the magical line by testing the board with a sound source and bingoooo the sound was so clear and my old dream come true
so thank you because you have inspired me
hafid from Algeria sorry for my English
unknownuser2007 (author)  aompes2 years ago
You are welcome! : )
hey thanks that was a tutorial. i have a problem intalling the aux jack i found the cable which is marked tar,tal.so can u plz guide me.i have attached snap shots of my boombox .two cables coming out from the casset mechanism. thanks
unknownuser2007 (author)  007.sammy1122 years ago
Hi Sammy-
Sorry but I don't know what those markings refer to. I didn't see any attachments either.
Even so, it is difficult to reverse engineer via correspondence. Even with the circuit board in hand, it isn't easy, especially when nothing is labeled. I did this mod to another boombox which I could not reverse engineer. The design was simply too complex for my experience level and tools available to me. I ended up buying schematic diagrams. Which I consider a last resort but not unreasonable since you can usually get them online for about $5.
Sorry I couldn't be more help. : (
jacobsteel2 years ago
amazing!- and yes, this must've taken a _long_ time.... good details, great instructable! thank you
unknownuser2007 (author)  jacobsteel2 years ago
Thanks for the comment! : )
Hey, ive been trying to make my tape player radio "ipod compatible" and tried the tape head techniuqe.Your right,it didnt work too for me,all i hear is static.Guess ill have to try step 1.
unknownuser2007 (author)  mastermakoko3 years ago
Yes, you have to probe around and get lucky. If all else fails, try to find/buy a schematic of your boombox online. I had to resort to this on a similar build. Good luck! : )
goethes3 years ago
nice work! i also got an old JVC stero with CD/FM/Tape. currently i just use a iphone dock and connect its line out to JVC's AUX in. but your work inspired me. :D
unknownuser2007 (author)  goethes3 years ago
Thanks! Post an Instructable on it! : )
scarrazzoni3 years ago
Tried it out and it worked. It was complicated, and I was pretty lucky. I found the right connectors messing around , nothing was labelled. The only issue is that when I select the CD mode and play a CD, sound only comes out from the right speaker. I don't really care as I simply use the AUX input that I created and, sometimes, the radio, which works fine. I powered the boombox with a 12V 2.3 AH battery that beautifully fits in the battery compartment (takes 8 D size batteries = 12V) and then i mounted everything on my bicycle :D. It sounds so well!
unknownuser2007 (author)  scarrazzoni3 years ago
Great! Another boombox repurposed! : )
Kaiven3 years ago
My left and right audios aren't blatantly labeled, though I can clearly see a left and right, I cannot tell which leads connect to cassette 1, cassette 2, or the radio. There are 7 pairs of leads from the input selector and I have no idea what connects to what.
unknownuser2007 (author)  Kaiven3 years ago
I was lucky, my board was labeled. You can connect the power and probe around. The common ground is pretty easy to find. Just be careful you don't short anything or shock yourself. Or to be safe you can purchase a schematic diagram online. I used 911manuals.com to buy one using Paypal. Sorry couldn't be more help. Good luck! : )
I fixed it up! I found two ICs and googled what they were, both were amp chips. I found which one affected the Tape I on the ghetto blaster and hooked my MP3 directly to the IC's input. I had to put 3.3k ohm resistors on both channels, but it now works fine. I can get audible sound with low distortion up to 500ft away!
unknownuser2007 (author)  Kaiven3 years ago
Great solution! : )
drkfox464 years ago
Thank you so much! This really improved my sound quality as opposed to the connecting my ipod to the cassete head.
unknownuser2007 (author)  drkfox464 years ago
You are welcome! I am glad it worked for you. : )
rhonyg5 years ago
Hi, how can I do if my selector switch is digital?
unknownuser2007 (author)  rhonyg5 years ago
Thanks for the comment. : ) Sorry but I don't have experience with a digital interface.
threewheela5 years ago
thanks soo much! your instructions on how to find a clean line helped me to complete a similar mod on an old sanyo radio that looks much like the one in your ible
unknownuser2007 (author)  threewheela5 years ago
Thank you. You are welcome! : )
boris1115 years ago
I'm trying your method by connecting directly to the line in on a Panosonic boombox. I'm not getting any sound out, but my phone does detect headphones.   I'm thinking the boombox needs to detect that the play button is pressed before it will turn on the amp.   Unfortunately I already canabalized the ribbon cable going from the casette to the board on the boombox.   Do you think putting a resistor from the 5 V cassette motor power to ground will mock the play button being pressed?
unknownuser2007 (author)  boris1115 years ago
Oh gosh too bad you removed the ribbon cable. 
I really doubt that the circuitry is sophisticated enough to sense motor movement or motor load. It's just a tape cassette drive but I guess it is possible.

Hmm, what else. Did you find the reed switch I mentioned Step 4, third photo? That may need to be closed/shorted to turn on the amp.

When you switch the function selector switch to radio, does the radio work?

I also ran across an Instructable called "Ghettoblaster MP3 player installation". Check it out because it is a Panasonic mod. You may see something in there to help debug your problem. 

Sorry I couldn't be more help. : (

I figured it out.   I needed to run a short from the 12 Volt power to a label called "Tape H"   First tried 5 volts, but that didn't do anything. 

Sounds great!    Thanks for writing this though.  It inspired me to bring new life to my mid 90's boombox instead of spending $150 on a new  boombox with comparable sound quality.
unknownuser2007 (author)  boris1115 years ago
Great! I'm glad you figured it out. : )
mpikas5 years ago
I see your left and right connections, but where did you connect the ground for the 2 speaker channels?
unknownuser2007 (author)  mpikas5 years ago
For the iPod connector, the ground is either Pins 1 or 2. They can be tied together since they are common. : ) 
Actually, I was wondering on the board in the boombox, where you wired the clean line at the selector switch, you showed the left and right signal connections, but not the ground.
unknownuser2007 (author)  mpikas5 years ago
Oh sorry. On the board it is usually the ground plane. Meaning where the negative is connected from the output of the transformer. The ground plane is common so it is at numerous places on the board. Usually these traces are very fat and cover a wide areas since  designers sometimes use them as a RF shield. Almost all bare metal parts are connected to the ground plane so you can poke around with a continuity meter to find it.
As with most things, I am speaking in general. There are exceptions.
Hope that helps. : )
Thanks, I can find the ground plane, I just didn't realize that you can use it for the signal... I guess that's why old school GM radios are a pain to make work with "standard" stuff since they run a negative signal to the speakers.
endolith5 years ago
What brand and model number is your USB charger?  Are any other pins connected besides the four you listed?

Are you sure the pins are actually numbered and connected like this?  Both 50K resistors are connected to both pins 25 and 27?  Why didn't they just use a 25K resistor?  These pin numbers seem to be reversed from yours: http://www.ipodlinux.org/wiki/Dock_Connector
unknownuser2007 (author)  endolith5 years ago
The USB charger was an off brand with the name of Inspire on it. I don't recall where I bought it. Sorry. I used the audio line pins too in my mod.

Sorry, I didn't realize my pinout links were broken. Here is the new link. Yes, the 50K resistors are redundant. I didn't realize this until later. A single 25K should work. However, it depends on the model iPod. Refer to the link for specific requirements for your model. Yes, the pin numbering is different depending on the connector. There is a note about it on the pinout page.

I highly recommend the PodGizmo breakout connector from Sparkfun. It is large but makes the modding so much easier! : )
nitorud6 years ago
Many thank you's on the post preamp connection idea. I was using a Panasonic RZ-3940 without L or R labels. I plugged my iPod to the ground before the tape preamp and started touching the R to spots that looked promising. Bingo. Now I can crank the iPod volume and the sound is pristine. Thanks for the post!
unknownuser2007 (author)  nitorud6 years ago
Great! Glad to help! : )
GamingRobot6 years ago
Nice im working on a project just like this but im having trouble with static i used the cd linein instead is the tape player linein, does the cd linein have a high inpedence? Also i shocked myself in the project!
turn down volume on ipod, turn up volume on boombox.
unknownuser2007 (author)  GamingRobot6 years ago
Thanks. Looks like you're doing a great job. When you say static, can you describe the sound? Is it like a constant hum or hiss? Is it happening only when you dock the iPod? Or is there static when the iPod is undocked? Does playing the iPod make any difference? There are many possibilities here. Yes, you have to watch what you're grabbing. An easy way of getting shocked is grabbing the bottom of the circuit board while it's still plugged in. Those solder joints are live! Later! : - )
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