[Amateur] OtterPopJunkie's Theatre Cassette Deck [DSL warning]

This competition offered me the excuse I needed to finally execute a project I've had in mind for a while (and do a two-year computer upgrade). I've got a matching Yamaha stereo set including a radio tuner, amplifier and tape deck from around 1981. All of them work perfect, but I really don't listen to tapes often anymore... however, I use my computer every day, and it currently takes up too much desk space!

Here's what I'm starting with: 1981 Yamaha Natural Sound K-350 Cassette Deck




It's part of a home theater stereo set with amplifier and tuner.

My goal with this system is a fully functional, compact gaming machine that looks identical to the original case - because brushed aluminum looks terrific.

After 5 months of planning and construction, here's the result:
Final Product:



Looks.. the same? My goal in this Project was to build the best (reasonably priced) computer I could into my classic tape deck while maintaining the original look. You can see I accomplished this goal, with a few sweet extras as well...

Skip ahead to Section 3 for all the final details.

Here is a video which shows it off best: YouTube- OtterPopJunkie's Cassette Deck Computer

This project was an absolute blast to finally complete, and I don't think I'll ever get rid of this case.. Love it! I estimate it took 200+ hours to finish over the course of several months (I started in February). Costs were probably >$120 for all the case parts and $790 for the computer hardware. Read on for the build log and how it all got started!

Sections:
1 - Planning/Purchasing
2 - Construction

2.1 Metalwork
2.2 Plasticwork
2.3 Electrical
2.4 Woodwork

3 - Final Product

Special thanks to Gary for assisting with measurements while I was out of town, Khalil for hardware advice and electrical engineering support, OCN for teasing me with prize money, and my employer for my Xmas bonus
Edited by otterpopjunkie - 7/4/10 at 10:28pm

Section 1 - Planning

I began by measuring the case. Here are some shots of the existing internals.



I made a 3D Sketch-up model of the available space. I began searching for PC components that would fit. The case is barely longer than 8" (which is a stretch for most new gaming graphics cards), and NOT big enough for standard micro-ATX motherboards! (which can be 9.6"x9.6" I believe). Combine that with having to fit in hard drives and power supply and we've got some figuring to do.



After many, many design iterations I finally settled on an anticipated use and balance of cost and performance. I'm very frugal, already have a HTPC, and I'm still very happy with my current system, so this was very difficult for me. I finally decided to upgrade to a faster gaming system and sell off my old system parts to offset the cost a bit. I went with the highest power PSU that would fit so I could use this as a gaming machine. Unfortunately due to space limitations this meant I had to buy nearly all new components.

DDR2 and DDR3 were same price, and my 4x1GB sticks wouldn't fit in case anyway, so upgrading to DDR3 made sense. New compact PSU was necessary. Smaller graphics card was necessary. Needed compact DVD drive.. etc.

Here are some images of the final sketchup design:



And here is a video that better shows the planned layout: YouTube- case mod Sketchup v6

The list of computer hardware installed is in Section 3.


Tools used:

• Variable power supply
• Scissors
• Drill press
• Hand Drill & metal/wood bits
• Paper & pencil & marker
• Soldering iron w/ melt tip and solder
• Screwdrivers
• Dremel/RTX with grinding/cutting bits
• Hack saw
• Belt sander
• Grinder
• Sandpaper (various types)
• Ruler
• Needle nose pliers
• Files (various sizes / types)
• Jigsaw
• Safety goggles, gloves, face mask and earplugs if necessary Always take the time to work safely, shortcuts are not worth the risk.

As for the rest of the design. I decided on uses for all the buttons/controls/lights on the front of the unit. Parts list was created, and price-shopping began.

Purchased parts from:
Digi-key, DealExtreme, Sparkfun, flexible PCI-E 10cm extension cable from ITXdepot (my first one ordered from BestOfferBuy didn't work!), radio shack and local hardware & electronics stores, and computer hardware from newegg, eBay and
others online.

Other Hardware required:
Aluminum (angle and straight), nuts/bolts, roofing zinc (great for mounting and small metal work - it solders), switches, LEDs, 22awg stranded wire, resistors, Super glue, Liquid & solid epoxies, mobo mounting bolts, plastic spacers, misc. Parts torn from old computers (cables and plugs), spray paint, window screen

After waiting a couple weeks (while I was out of town) I ordered all the computer hardware from Newegg at once to save on shipping to Alaska. Once I returned home I began work on the case and placed orders for parts as needed down the line. The first thing I did back in town was clear off a nice clean workbench to start with:



Although that definitely didn't last for long.. a preview of what's to come:



All my computer parts arrived and I disassembled the tape deck to start test fitting:




It looked like everything would fit as planned.

I then benchmarked the system and folded on it for several weeks to make sure everything ran smoothly while I started modifying the case.



Unfortunately the first cheapo PCI-flexible extension cable I ordered didn't work properly, so I had to drop some cash to buy one from a reputable seller.

All the remaining planning happened on the fly.. there were a lot of unknowns going into this project and I didn't have space to spare, so there was only so much I could plan for and the rest was try it out, then fix it!

Read on for the nitty gritty construction details!
Edited by otterpopjunkie - 6/30/10 at 8:36pm

Section 2 - Construction

The construction log is roughly organized into four sections, in roughly the order of completion:

1. 2.1 Metalwork
2. 2.2 Plasticwork
3. 2.3 Electrical
4. 2.4 Woodwork

2.1 METALWORK


MOTHERBOARD MOUNTING

First, I test fit the motherboard until I convinced myself I had it in a good spot. Basically I wanted it as far back and to the side of the case as possible to avoid any interferences later on. I marked the mobo mounting hole locations on a piece of paper and used that to mark the holes on the case.



At this point it's critical to double check you have the correct spots, and while mine were slightly off everything fit. I drilled the holes in a drill press, and bolted 1/4" riser nuts to the case. This way there is no chance the motherboard will get shorted. Double checked everything again, and then I used a large drill bit to ream off any rough edges on each hole (this is something I did throughout the project). Make sure to wear gloves and safety goggles whenever working with metal - trust me, you don't want metal shavings embedded in you!





As one of the more difficult parts of this mod, I definitely procrastinated on the metalwork. The case was 1/20th inch thick steel on the back and bottom, and I anticipated designing the layout, bringing it to a friend's workplace and having him cut it out with a waterjet. I soon realized this wasn't going to be an option because of the tight tolerances in the case - it turned out to be a trial and error job to make everything fit just right.

After mustering the motivation I finally started with the most straightforward cut, the hole for the PSU (Power Supply Unit). After placing masking tape over the backplate to preserve the painted text labels I marked the location for the hole.



I decided to cut around the existing power line hole for strength, but also so the “Mains” label remained – perfect! Using the drill press I drilled large holes (~1/2”) near each corner.



Then I securely mounted the backplate against a wooden 4”x1” in a vice. Using a jigsaw with a fine metal blade I cut along my marks until I could remove the scrap metal.




I then broke out the files, starting with the large flat files to straighten and enlarge the sides, then a large round file for the corners, before using smaller finer files to smooth everything out. A bit of fine sandpaper can also help smooth the edges out. And remember, wear gloves and goggles when metalworking! I cannot emphasize this enough. The same drill, cut, and file method was used for all the metal holes following as well. Here is the first backplate hole completed:



To place the PSU flush on the metal case I also had to remove some metal bends in the bottom support. The metal was too thick to pound out by hand, so I drilled out the three metal bumps and then filed them smooth:





Next I eyeballed, marked, measured, eyeballed and measured again until I had the rear mobo (motherboard) connector panel marked and ready to cut.



While this was a straight cut, my placement of the mobo required me to get very close to the edges of the backplate, and I had to make the size just right so the thin panel cover could snap into place and stay. This took a lot of filing, testing, and filing again.



Remember, measure twice and cut once - and if you're not sure, stay on the safe side and file away later! I was finally satisfied with the location after trimming some of the panel away (because I didn't plan that well ahead when mounting the motherboard). Live and learn, but I got all the rough edges bent/filed out and it worked out allright! Finally I was able to put the motherboard and backplate in place at the same time, and make sure everything fit:



Please continue reading on the next post...
Edited by otterpopjunkie - 6/30/10 at 8:38pm

Moving on, I had to make the decision of where to mount the graphics card. This is a dual slot card, will I use a single slot later? Do I want to leave room for a larger CPU cooler later? Should I mount it flush against the wooden cover, or leave more room for air? Is the cable long enough?.



After lots of thinking, I finally got it where I wanted it, and marked the holes. After spending some time measuring temperatures on the card while folding, I decided to place it nearly all the way against the top of the case, as I anticipated drilling holes for ventilation later - but if not I thought it would stay in the acceptable temperature range (dual-slot cards usually cool well).



The same story again - marked the location, drilled, and hack-sawed away. Double check, file some more, and finally done.



In order to mount the card I had to remove the metal plate on the back and bend it flat using a vice and steel bars so it could mount flush against the back of my case.




I fashioned an aluminum plate to mount the flexible extension cable to and also provide some extra support for the card, since it hung sideways in the case. Finally I had the holes drilled and bolted it in place.



While I'd prefer it be more stable, it stays in place well and is rigid enough for transportation. Adding more metal could have complicated the design and made it harder to swap out components - and I am definitely a believer in K.I.S.S.: Keep It Straight and Simple. You can see the final mounting system below, held in place by two bolts. The nuts for each bolt are super glued in place so they won't fall off in the case when attaching/removing the card.




I also had to cut an opening for the case fan. I used the same procedure as above, drew a circle using the fan guard as a guide, drilled a hole on one edge, then secured it against wood while I used a jigsaw to cut out the hole. Plenty of filing later, I had a good looking circular hole despite the case bottom having a funny shape.



The finishing touches (for now) were made to the metal frame: I made sure all holes were burr free and everything was free of metal shavings. I also drilled a few small holes underneath the mobo on the side of the case to allow some airflow underneath the board.


Edited by otterpopjunkie - 6/30/10 at 10:11pm

PLASTICWORK

Before I started hacking apart this tape deck, a small cover would flip down to reveal the tape read/write heads, and you placed the tape into the deck. However I needed a door on this part of the case so the DVD drive could slide out, so I had some work to do. I started by swapping my soldering iron tip for a flat one that I could use to melt away the case plastic. Not all plastic-like materials melt (some burn), but luckily this case was a thermoplastic that melted quite easily.



Using a well ventilated area I started outlining the metal backing that the tape normally sat against. Eventually I got all the way around, so that a groove was melted in the plastic leaving only the aluminum cover left.



I punched this area out, and cleaned up the case edges with a razor.



The now-separated backplate now had to be trimmed down to size and attached to the small cover.



I spent a few hours shaving off metal on the plate so that it was small enough to fit through the brushed aluminum front cover. This took a lot of trial and error as well, and I had to come back at least twice when I started putting things together because things started to rub. I taped the flip cover and the tape back plate together and tested it out to make sure it flipped down, and finally epoxied them together:



Now, I removed the capstans (little black knobs that spin the tape) from the original deck parts, glued the little pieces together, and attached them to small tabs of zinc roofing metal to restore the original look of the tape backplate. With one important point: the right capstan is attached so you can push it back – and this is what hits the DVD tray button to pop the door open:



After I had the flap door complete, I built internal mounts for the DVD tray and hard drives using straight and angled aluminum. The aluminum mounts are bolted to the frame and the drives are bolted to the aluminum.



I later added another support for the DVD tray between it and the fan, to allow the second hard drive to sit on top of the DVD tray.



Directly below where the tape went in the deck are the control keys. Pause, play, record, etc. I cut a rectangle of aluminum out to fit behind the original keys, then I took each one and cut the ends off so I could glue them onto the aluminum. Hacksaw, beltsander and lots of measuring took place here to make sure they were all cut equally.



After some measurement checking, I cut out a section of the aluminum bracket for the USB ports. The side-by-side ports I bought had a rubber backing that bolted on, so I had to drill holes for this. Later I found the bolt on the end interfered with the case, so I ground it down a bit and melted some more plastic out of the case. I used the brush attachment on the grinder to sand down the aluminum to a (close) matching brushed look for the visible part.




I then taped all the keys together with toothpicks to maintain the correct spacing and glued them all onto the aluminum at once, checking periodically to ensure the correct alignment.




Test fit in the case, the keys look like they belong there!



Now, I had to fashion a cover for the USB ports. With my cheap iPod cable from Amazon I broke out the metal USB connector, then cut a hole for it in one of the remaining two keys. Again, more painstaking measuring and alignment and I figured exactly how I wanted the connector glued on. Using the solid epoxy mix I mashed the epoxy for three minutes until it was the same color, then glued the pieces together. Here’s the result:



Now, as it turned out I couldn’t have two separate keys (one for each USB port). Things just wouldn’t line up so I had to attach the two keys together. I cut out some aluminum, and after two tries I made this piece with a grinder and file and glued the keys together:



Hey, it fits! Success!!
Edited by otterpopjunkie - 6/30/10 at 10:14pm

ELECTRICAL

Since the case already had a power and reset switch (for the tape counter), I wanted to utilize those buttons for the computer power and reset buttons. The original power switch was a single-pole/double-throw switch, so I had to replace it with a momentary pushbutton switch. I got a switch from RadioShack and cut out an aluminum mounting plate so I could attach it to the original case. I measured the lengths, and cut down the original switch to fit, then epoxied it to the pushbutton switch as shown. Toothpicks and tape held it while gluing. Afterwards I mounted it as shown in the correct location. The glue didn't hold the first time, but I reglued it later and it's stayed strong since.



For the reset switch, I used a momentary contact switch I salvaged from the tape deck. The original switch was mechanical, so I had to attach this switch so the plastic arm made the connection. I wanted to leave the original tape counter in place for looks, but also intact so I can use this down the road should I want to add a counter of some sort to the machine (possibly showing hours running?). I drilled a hole in the plastic for a tab on the switch for rigidity, and after I failed to screw the switch on I ended up epoxying it in place (see photo below).




Moving on to the dynamic parts, the LED backlighting and fan controls! I needed a good use for the buttons on the front, so after a couple hours late at night I found some low-profile SPST (single-pole/single-throw) switches online from Digikey that would fit well into the case. In order to mount the switches as close as possible to avoid interfering with the motherboard I filed down the mounting threads and fit the switches partially inside the front of the case. To hold them in place I epoxied bolts to the plastic and made an aluminum bracket to hold the switches in.



I’m missing some photos here, I guess I got too wrapped up to take any. But you can see here the rest of the electronics on the back of the case. I mounted two low-profile microphone inputs to match the front of the case (originals were too big to fit), and also enlarged the knob hole so I could fit a multiple-position rotary switch large enough to handle all the current from my large fan (19W max). Originally I wanted to control the fan with a potentiometer but I wasn’t able to find one small enough to fit in the case that could handle that much current. Instead, I placed resistors in series around 5 positions on the rotary switch. At the lowest speed the fan gets approximately 4volts after ~50ohms resistance, and at full speed there is minimal resistance so it gets the full 12 volts. The fan I bought is a very high powered fan, so it’s too loud to run at full speed all the time. The front panel gets 12v/5v power via a molex connector from the PSU, then passes on the controlled power to the fan molex. The fourth switch on the front turns this case fan on and off.

After mounting the rotary switch and pushbutton switches in position, I started assembling the LED backlighting. As you can see in the above photo, there were originally two green lamp bulbs that backlit the glass panel with the VU meters on the front. I replaced these with various LED lights mounted on a strip of aluminum:



To construct this I marked the position of each bulb on the aluminum and drilled out the holes with a drill press. The LEDs almost stayed in the hole by themselves, but I helped them with a few drops of super glue. While I originally planned on wiring all the LEDs in series to be more efficient, I decided to wire them in parallel to make less of a mess of wiring. This way I could use a common ground for all 18 bulbs, and a single wire running across for each color of lights.



I soldered each wire, pulled back the coating a bit, soldered the next, cutting out sections of coating so that there was no way the wires would short. Lots of bare wires would be asking for trouble.




I calculated the resistance I needed to drop 12v to the 3.6v and 2.2v level required for the different colors, and made a stop at the store for 1W resistors (I required about 0.8W). After grinding the tops of the LEDs and the plastic case a bit to make things fit, I tested the look out and attached the bar. The switches were then wired. They used to tell the deck what kind of tape was in use, but now they control the backlight colors:
LH is green
CrO2 is red
METAL is now UV blacklight! (I can tan while gaming! Just don’t stare at it.)
And they can be combined to form a bright purplish-bluish light as well.




Now I ran into a slight problem, the bolts holding the switches in place were a tad too long. I cut them down to size using a Dremel and metal cutting blade. This worked just fine… until I later realized this fine metal dust collected inside my VU meters, despite being sealed away in the front of the case! I mostly remedied this with a whole can of compressed air, so it doesn’t seem to be a problem now.




And for another really cool part.. the VU displays! I intend for the first one to show the fan speed, and the second to show volume or case temperature. While I originally wanted to design a circuit to utilize the tachometer (yellow wire) signal from the case fan, I later realized this was really unnecessary since it is unlikely I’ll use a PWM fan later (not to mention I’m not an Electrical Engineer ). Rather, I connected the VU (Volume Unit) meter in parallel with the fan voltage (controlled by my rotary switch). Through a small resistor the VU meter shows the voltage of the fan, such that at 12v (100%) it reads 0dB (100%) on the meter and 40% at the lowest speed). So you know when it’s on and what speed it’s running! Check out the video in the final Section 3 to see it in action.


Wow, this is a lot of work! But things are starting to shape up… and I’m getting excited for the final product! I now had to make use of the microphone inputs I mounted, the original phono (headphone) jack, and remaining potentiometer on the front of the case. I found the pinout for my AC’97 front panel connector on the Asus motherboard online (common layout) and started looking for a 5x2 pin plug to connect to the motherboard… no luck at my local source. Luckily I snagged some 4pin connectors from an old computer recently, so I started hacking away. I cut one end in half and glued it to the other 4 pin connector, creating a 6 pin custom connector.



I soldered and shrink-wrapped the wires and cable, then cut it to length and attached all the wires to the front panel connectors, using the potentiometer to control the headphone volume. At this point I still haven’t tested any of this (because my mobo hasn’t been back in the case), but hopefully the pinout and all my connections were correct! We’ll find out later.

Here’s the inside of the front panel:




Not much room, is there? I cut off part of the 24pin mobo power connector to make it fit with that aluminum mounting plate there (no problem with that). I soon used black cable loop spool stuff to organize all the wiring and give it a cleaner look (and hopefully better airflow through this cramped case).



The final (mess of) wiring can be seen at the end of this log.


And finally we get to the case temperature sensor. The second VU meter was unused, until I was able to get my temperature sensor to power the meter. This required a long time testing circuits on a breadboard, until I finally got one that worked thanks to my electrical engineering buddy Khalil. Using two standard op-amps, a LM335A analog temperature sensor and lots of resistors, we came up with this circuit, which initially used a test VU meter to avoid frying the important one:



This takes the 1.4-1.5 volt range output from the temperature sensor and converts it to 0 to 0.6V, the correct range for driving the VU meter. Once I got the circuit working on the breadboard I mounted it on a PCB and installed it inside the case behind the VU meter:



Here is a video of the meter in action, heating it up quickly with a blowdryer:

YouTube- OtterPopJunkie's Cassette Deck Temp Sensor
Edited by otterpopjunkie - 7/1/10 at 8:53pm

WOODWORK

Definitely the smallest section of the project, but also one of the most important. The original (fake) wooden paneling covering the top and sides of the case gives it a classic feel that I really couldn’t mess with. Yet, I needed effective ventilation if I’ll be folding for the cause 24/7!

Earlier during some case work I ran some tests to check airflow in the case. I mounted everything inside and covered/taped the case with cardboard. Turned it on and started some burn-in tests. Temperatures would definitely be a problem without airflow, but when I had the case fan on full speed it was so powerful it caused the PSU fan to reverse – definitely not ideal. So for now the case fan will blow into the case. I added some screen mesh over the PSU fan since it’s right next to the case fan, this way the case fan will blow nearly all the air out the side near the CPU.




While originally I planned to drill a grid-pattern of holes directly above the CPU for ventilation, I later decided it would be best to drill large holes and avoid the potential disaster of perfectly aligning, drilling, and painting 50 little holes. So, it had to be done on the side of the case (or nothing could sit on top!). I measured where I had room to cut so no metal would be exposed inside the case, and determined a size that (should I want to later) matches a common small fan size. So for now I only have one large case fan, but now I have the option later to add more smaller fans. I triple checked the hole locations and drilled away. It's important to note here that I sandwiched my case between two pieces of wood to keep the edge nice, and only did this after drilling many test holes in similar wood:



And here we can see the light colored wood inside – definitely not blending in. I masked over the holes with tape and used a can of spray paint I had lying around to paint a flat black on the edges of the holes.



I’ve seen other old stereos that use mesh screen for ventilation holes – so that’s what I did. With some spare window screen (don’t tell the neighbors.. jk) I spray painted it matching black and mounted it inside the case. The tape is temporary, I assure you.



ANNNND now I can finally see what it will look like when it’s done! I was bouncing around at this point, 95% complete but yet still a project log to finish… have to get it done 100% before I start showing it off! The fan is there to show the size of the hole, I haven't installed any there yet.

In Section 3 below you can see the final product!
Edited by otterpopjunkie - 6/30/10 at 8:24pm

Section 3 - Final Product

The final computer is indistinguishable to the cassette deck I began with (at first glance), and while it no longer plays tapes it has a few new features:

• push the right capstan, and the cover opens and dvd tray pops out.
• the left VU meter shows fan speed, 0 to 4500rpm/100%.
• the right VU meter shows case temperature, from room temp to ~50C.
• left knob controls fan speed
• right knob controls headphone volume
• switches control three different sets of colored backlights: green,
  red, and UV (blacklight)
• Dolby noise reduction switch turns off the loud case fan
• REC light shows HDD activity
• working power button, reset button, headphone and mic jacks!

Here's a video showing all the new tricks: YouTube- OtterPopJunkie's Cassette Deck Computer

And final photos of the completed inside and outside!




















Here are the final system specs:

• gfx: ATI Radeon 1GB HD 5770
• ram: Kingston 2x2GB DDR3 1333
• cpu: Intel Core 2 Duo E8400 Wolfdale @ 3.0GHz (6MB L2 Cache LGA 775)
• mobo: ASUS P5G43T-M Pro LGA 775 Micro ATX
• psu: Diablotek PHD Series PHD380M 380W Micro ATX Power Supply
• hdd: OS: 250GB Sata2 7200rpm Samsung Spinpoint F1
• hdd: GAMES: 2TB Sata2 HITACHI HD32000
• dvd: 8X DVD+-RW Sata2 laptop Drive
• fan: 4500rpm Vantec 92mm

Thanks for checking my mod out, remember to vote!
Edited by otterpopjunkie - 7/4/10 at 10:26pm