Introduction

The Sony MHC-3600 is a mini HI-FI system featuring an amplifier, tuner, CD player, and tape deck. This system, produced in 1991, has a bit of history—it’s older than me! My dad bought it second-hand long ago. While I don’t remember how it sounded back then, I recently wanted to listen to some good music on cassette and discovered that all I could hear was a ticking noise. I liked the beat, but I don’t think it’s supposed to sound like that! Shouldn’t I be hearing “Forever Young” by Alphaville? Upon closer inspection, I noticed the cassette reels weren’t moving…

Research - How Tape Deck creates the sound? 👨‍🏫

We need to start with the basics, how tapes work? Similarly to Vinyl, tapes are analog. It means, that we need a complex mechanism that will move the magnetic tape, and convert the signal to electrical signals.

Front tape deck mechanism Front of the mechanism - Some Kenwood deck

Playback Head is what reads the encoded audio information from magnetic tape, it converts magnetic signals to electrical signals which are send to amplifier, and further to speakers.

Supply reel holds unused portion of the magnetic tape, as the deck plays the tape moves to Take-Up reel which collects the tape after it has passed through the playback mechanism.

Capstan and Pinch Roller ensures that the tape moves smoothly at consistent speed without slipping.

Back tape deck mechanism Back of the mechanism - Sony MHC 3600

After turning the mechanism around, we can see the motor belt and the capstan belt. The capstan belt is not in place because it needs to be connected to the motor, which would then completely cover the mechanism.

Motor belt is responsible for setting the mechanism in motion.

Capstan belt is responsible for tape transport.

When doing research about tape decks, I noticed that they are often the source of problems with playback. The reason for this is that belts are made of rubber, which tends to break with age, especially when the machine has not been used frequently. The rubber gets loose or even turns into a sticky goo, preventing the reels from moving.

This will be the first thing we check on our Sony MHC 3600.

Disassembly

First we need to open the case. Unscrew the bolts on the sides, and slide off top part of the case.

Opened sony mhc-3600 Unpin the connections, unscrew bolts on the bottom and slide the mechanism to the front.

Sony mhc-3600 PCB According to service manual, we need to squeeze PCB connectors using pair of pliers.

Sony mhc-3600 Motors PCB We need to unscrew motors PCB.

Sony mhc-3600 reel mechanism We finally got to the belts!

Cleaning up

As you can see belts turned out to be sticky goo, we have to replace them. But before we do so, we need to clean the mess up! First, we need to take the remains of old belt out. Next, its important to clean the reels and capstan. What do we need? Q-tips and something alcohol based, I have used nail polish remover. Carefully take some of the cleaner on Q-tip and start the brushing.

Cleaning reels with q-tip and nail polish remover Cleaning left over belt off the reel

Replacing belts

If you are repairing your gear along with me, and your belts look alright, but they are old I would still recommend to replace them. As time goes belts tend to turn loose, which may cause slipping on reels, which may cause problems with playback.

Broken belt That belt fell apart in my hands!

Before replacing we need to make sure that we have the right size of the belts. How? I recommend to look for belts made for your specific model. There’s a chance you will find them in online auction shops, like Ebay. I have found Sony MHC-3600 belts on Allegro. If you wont be able to find them, its best to get a bag of belts with different sizes.

Bag of belts Bag of belts I have ordered for a different project!

Place the new capstan belt around the capstan motor pulley and the flywheel. Ensure the belt is properly seated and not twisted.

Motor belt placed on the reel Motor belt

Capstan belt placed on the capstan holder Capstan belt

Next, we need to assemble the parts together in the same way we disassembled them. If you have problem with this step, there are a lot of videos on youtube about similar models, that can help you.

Cleaning head

After we assemble everything, its a good idea to clean the head.

Cleaning the head is as important as having proper belts. It’s important for maintenance because a dirty head may cause the sound to be muffled. This may not be the case now, but it’s still worth making sure the head is clean, as it takes only a moment! If you have a tape deck or Walkman you would like to listen to, I encourage you to do it with me!

Use a Q-tip with alcohol-based liquid!

Cleaning head with q-tip and nail polish remover Cleaning head

Also, make sure that pinch roller, and capstan are clear. If those elements are dirty, they can cause the deck to eat tapes!

Forever Young

Is Sony MHC-3600 Forever Young after these fixes? Of course it is! Although there is a problem with CD tray, which does not want to close sometimes, I hope I will soon find the time to fix it too, and that you will me join me!

Nonetheless, enjoy the sound of good ol’ cassette tape! :)

Emotion98.3

Have you already seen my project Emotion98.3? It is a web app that allows you to enter the realm of the 80s vibe! I warmly invite you to check it out! I couldn’t resist and have played Emotion98.3 radio on that HI-FI system. Take a look at the video below!