The Story.

The year is 2008 and I'm sitting at my desk looking at and listening to my beloved Sanyo M9994 boombox, a model that I had also owned having purchased a new one 35 years ago as a teenager only to have it "stolen" from me by an opportunistic "friend." I realized that this sad looking and sounding boombox needed a lot of work. As a teen, I worked many days and nights to save the funds needed to buy that Sanyo and believe me, it was a lot of money in today's dollars. Prior to the purchase, I read all the stereo magazines, visited and pestered all the salesmen at the stereo stores. Unlike today where electronics are all sold by big box stores, back then, individual entreprenuers grew like weeds and they were places where you could actually haggle on pricing. Try that at your local Best Buy store and see if they don't laugh at you. These salesmen all knew my name. If there is one thing I can assure you, the things you worked hardest for in your life are also the things you appreciate the most.

Anyhow, like most collectors who coveted these fantastic electronic devices of old during our younger years when we either could not afford, or were just barely able afford, I was no different. Now older, more financially capable, with the world in our hands through connections of the internet, and with accounts at eBay and Craigslist now at our disposal, it has become the perfect storm for us to really grow our collections. Unfortunately, while we are older, wiser and arguably "better, lol" these boomboxes also aged along the way and get old, they do. In fact, it's a fact that these old boomboxes have well eclipsed their design lifetime.

I decided that having worked on home audio gear, why not devote some of my free time to the "restoration" of one of these beauties? There was definitely a fear that I was throwing time and money away as the final result might not be worth the effort expended. I would later put this to the test (continue reading this story). Unfortunately, at some point, I would lose all of my photos I snapped during this restoration to a hard drive crash and I was only able to restore some through a costly recovery service. So I am unable to show images of all the work performed.

Several phases of the restoration are involved. There is the Cosmetic restoration, then the mechanical restoration, and then there is the electronic restoration.

Phase 1, Disassembly and cleaning:

After 35 years, you can bet that internally, there will be lots of gross looking things. This was certainly the case. Huge dust balls, grime, grease, bugs.. you name it. The first thing was that all major pieces were taken to the garaged where all dust and loose bits were blasted out with shop air compressor and nozzle. Every board, the front and back cabinets and the deck mechanism were then all cleaned with detergent and a garden hose and a soft paint brush as well as a smaller soft bristled toothbrush. While it may seem weird to wash an electronic board in soap and water, it harms nothing. There are cases of folks in the hi-fi audio forums having washed entire home stereo receivers in the dishwasher. I haven't tried that, but I do know that in the summer where weather is very dry, cleaning and immediately allowing the components to dry in the sun has never been a problem. The low humidity basically sucks all the moisture out of the boards after cleaning.

Phase 2, Mechanical Restoration.

These photos were lost but the tape deck was removed and disassembled. The belts had turned to black goo and took hours to clean up. Using 100% tech grade isopropyl alcohol, I was able to clean them off, but in the process, the black tar got over everything. My hands, the carpet, the countertop, on my pants and face. Everytime I cleaned up, I would find a new patch of tar someplace else, seemingly appearing out of nowhere. It was a mess and in my experience, Sanyo's belts are some of the worse due to this liquifying form of degradation. The best way for these to fail is to simply dry up and crumble since it leaves no mess. This was the worse. The heads were in decent shape but covered with a rough gritty feel. Using standard head cleaner specifically designed for cleaning heads had no effect. While not an approved form of cleaning method, I used a polish and elbow grease to "polish" the heads to look like new. To those that frowns on this suggesting that such cleaning could destroy the heads, all I have to say is that not only was it highly effective restoring the heads to like new appearance and smooth feel, the sound was markedly improved. Perhaps the polish might've shaved a bit off the top during the cleaning process, much like a powered buffing session might do to the paint on a car finish. But this wasn't something that was going to be done day after day, and who uses cassettes much nowadays anyhow? Restoration was the goal and reduced deck use presumed to be a virtual certainty due to music source having gravitated away from cassettes years ago. With less reliance on cassette decks, any life reduced from the polishing is in my opinion, inconsequential anyhow. The Sanyo deck also relies on a couple of nylon disks with felt sandwiched in between. These disks is a clutch. Over the years, the disks get "polished" and loses their grip allowing excessive slippage. To restore, the assembly was disassembled and the disks was deglazed by spinning them by hand over steel wool. The felt pads were cleaned with IPA and then the nap was raised by brushing them. All of the belts were replaced and all microswitches were cleaned. Any pittng on those switches were cleaned with 400 grit sandpaper placed between the contacts, and pulled out with the contacts closed on the paper. Preservative was used on all cleaned contacts. All mechanical and moving parts were lubed if they had old grease and left dry if they appeared to be intended that way. The cassette door damper originally used a thick grease which by now all turns to oil and seeps out. I could not find grease that was thick and sticky enough to have the desired dampening effect so I used the thickest silicone grease I could find instead. I did find some automotive wheel bearing grease thick enough to work but I was concerned about the long term effects of the petroleum based grease on the plastic parts. A good compound that does seem to work and result in the proper dampening action is white plumbers thread sealant. They are supposed to never harden. Only through long term use will prove or disprove that.

Phase 3, Electronic Restoration.

Now we are getting into it. A standard servicing always include solvent cleaning of the controls to remove oxidation. This was performed everywhere there was a switch, control or contact. To do this service right, you do need to disassemble far enough to get at the access holes usually present on most controls. Luckily the solvent sprays have thin straws that help get the solvent where it is supposed to. Wipe off the excess. I did not do that on this boombox but I am now inclined to disassemble most controls because I have found that a far better cleaning can be performed and the effects of the cleaning more durable than just spraying externally. Additionally, the feel of the controls simply can't be restored without a proper disassembly and lubing of the control slides or shafts.

This is an image of the PCB before recapping service. Note the wire looms tethered everywhere which blocks access to much of the caps. In this photo, it doesn't even look like there are many caps to replace. You will soon see how many there will be. All of the looms needs to be unbundled and should be restored to the proper location when service is completed.

Here are images of the replacement cap leads before being snipped. Although it may seem like it would be better to just snip them off as they are installed, I found that having them protruding made it easier to determine which caps were replaced and which were not. They also acted as placemarkers making it easier to navigate and match the top and bottom pin holes or pads, which is a far more difficult task than you might imagine.

Here are images of the boards having been recapped. Most of the replacement caps are Nichicon gold audio grade which costs substantially more than regular replacements but given the labor intensive aspect of the service, the cost increase was a good investment.

This is a photo of the tone control board. Notice once again, the gold Nichicon replacements. The tone controls were all cleaned of course.

Phase 4, Cosmetic Restoration.

Luckily, the antennas are original and intact, a rarity it seems these days. The rest of the cabinet however has seen better days. The speakers were all faded and the chrome dust caps were all rusty and tarnished. I dyed the speaker cones with fresh black and the caps were painted silver. While not identical in looks to the factory chrome caps, the fresh clean look is definitely far better than faded speakers with tarned rusty caps.

The front cabinet was then stripped down except for the side trims which did not want to come. The top panel was already somewhat loose which was a blessing. After going through the stripped cabinet some more to ensure complete cleanliness, it was masked for a new coat of charcoal gray.

The shell repainted and drying. I used charcoal gray which is sold by automotive parts stores for use on wheels. It seems pretty durable and I clearcoated it to give it a good finish. After that, the side trims were restored by giving it a brushing with a brass brush going in one direction. This gave evened out the finish and those trims were than also clearcoated to protect them as much as possible. The top trims, once reaffixed were also top coated with clear to protect the silkscreening.

The top panel, which was clearcoated.

The acrylic meter panel are held in place by plastic rivets. I removed them by carefully cutting off the mashed pegs from behind with an exacto hobby knife, then pushing them out from behind. This panel needed to be removed in order to paint the cabinet. Also, it's usually pretty grimy and grubby behind that clear panel and it is not possible to do a proper cleaning without removing it. Luckily, the silkscreening is on the acrylic panel and not on the cabinet. On another future example I worked on where some rivets were missing, I did replace them with small head screws that were painted black. As you can see, after cabinet repainting and reinstallation of the panel and meters, the results looks like brand new. Notice also that the grills are repainted. Additionally, this shot probably best depicts the new gleaming sheen of the cabinet, which looks far newer than a brand new M9994! In real life, the results is stunning.

The back and front cabinets, repopulated after cleaning and degreasing. As you can see, clean enough to eat off. They did not look that way before!

After reassembly, all I can say is that the results were well worth it. In the beginning of this story, I told you that I would put to the test about recovering the what was invested in this boombox. I did eventually sell this through eBay for, if memory serves me correct, $600'ish. I wouldn't say I profited off the sale nor did I lose money. However it was a fun project and I wanted to move onto other projects and needed the funds to help finance those other projects. After reassembly, the deck was adjusted for tape speed, azimuth (using oscilloscope to check phase alignment), the tuner worked wll aside from a small tracking adjustment and pilot signal centering. The sound was incredible. All I can say is that there definitely is a difference between an example with aging caps and one with fresh modern caps. I often wonder about this model but I hope that the new owner took good care of it, and that it's still rocking.