In this instructable, you will learn how to properly clean the tape path (heads, pinch roller, and capstan) in a cassette recorder. Why clean a cassette recorder? Tape requires physical contact between the media and what reads it. It also requires speed that is accurately controlled. These two things can be adversely affected by a poorly maintained machine.
It is assumed the reader has some basic mechanical dexterity. No special tools required. If you can build puzzles or you played with Legos as a kid, you can handle this!
Supplies you will need..
1) Q-tips or similar
2) denatured alcohol (recommended) or good quality rubbing alcohol
3) magnifying lens (can be of help to those with diminished eyesight)
Step 1: Why Routine Cleaning Is Needed.
Why does a cassette recorder need cleaning?
All cassette tape recorders work by passing a sliver of oxide coated plastic over a tiny metal encased coil that turns the magnetic variations into an electrical signal which is amplified and turned into the audio you hear. This tape needs to be moved along at a precise speed in order for the audio to be both intelligible and enjoyable.
Tape recording has been in existence for well over 60 years now. The first cassette recorder was sold in 1964 and by the late 1960's they were everywhere. Like everything else, improvements were made in both the machines and the tapes.
All tapes shed oxide, some just shed much more than others. This oxide presents itself as a brown residue on certain parts of the tape machine. If ignored, it just keeps caking on reducing the highs in the audio at first and progressively making the sound muddier. It will not only affect the audio but can also adversely affect how the machine handles the tape. Worst case scenario the tape is skewed, pulled at an angle, which permanently damages it by leaving creases. A machine that skews tape will eat tape. One of the joys of cassette tape is having to look for a bic pen to try to manually rewind a tape a machine has eaten!
Cassette tech reached it's peak in the mid to late 1980's. The best cassettes were from that era. Premium tapes from the 1980's don't shed anywhere near as much as do cassettes from the 1960's for example. Why do you need to know this? Play one 1960's era Ampex cassette and your machine will be filthy. Play 20 1980's TDK SA cassettes and you may still have a clean machine.
In the pic there are two cassettes. The top one is a BASF from the 1980's. Note the shiny dark color. The lower one is a Scotch from the early 1970's. Note the dull brown color. Those older dull brown tapes are capable of soiling up the heads in just one pass.
For a real in depth look at different cassette formulations and some history check out this instructable.
Step 2: What Parts to Clean and Where They Are.
Let's get into the parts of a cassette recorder that need to be cleaned.
You have 4 primary parts that need to be cleaned on a cassette deck that records. 3 if you have a play only machine.
1) pinch roller
2) capstan shaft
3) record/play head
4) erase head (only found on recorders)
You will see some pics pointing these items out on 3 different machines. First one is a typical "shoebox" cassette recorder, the second is a microcassette deck. Both of these machines function in the same way despite there difference in tape size. Some parts are in slightly different locations but they do the same thing. The third pic is from Wiki and I added tags to show the name of the parts. This let's you see how everything looks when play is engaged with a tape in place.
The pinch roller is a rubber roller that presses the tape against the capstan shaft to control tape speed and keep it steady when playing or recording. The capstan is a metal rod that is connected to a flywheel that is hidden from sight. It provides mechanical control of tape speed. The record / play head is what actually reads and writes the audio signal to the tape. On very expensive machines there will actually be a seperate record and playback head in the same housing. It is cleaned the same way regardless. Finally we have the erase head which is only found on machines that record. It's purpose is to erase the tape before it reaches the record head. It's only active when the record button is pushed.
On the microcassette recorder pic, you will notice that the capstan and pinch roller are in the middle and the record/play head are off to one side. The erase head is not visible in the pic because on some machines it's actually a tiny magnet that swings out to contact the tape when the record button is pushed. Fullsize cassette recorders with lowend mechanicals will use this swing out, permanent magnet erase head system. You will find it in modern day boomboxes that still have cassette for example.
Step 3: Q's and Chems
What to use?
You will need Q-tips or other quality cotton swabs. The cheap ones can be frustrating as they dont have enough cotton on the end or it comes off easily. The next item you will need is denatured alcohol. This is what's reccomended by tape techs as the correct liquid. Denatured alcohol can be found at most any hardware store but the issue is I have never seen it in less than quart sized containers.
What about something else that gets the job done?
I have been playing with tape recorders since the 1980's and always used rubbing alcohol and Q-tips. This undoubtedly makes some folks cringe with good reason. Rubbing alcohol has some light oils in it. You don't want to leave an oily film on your heads. What I have always done is after giving the machine a thorough cleaning using rubbing alcohol, I follow up with another pass using just clean, dry, Q-tips. Clean machine, no residue, no weird can of denatured alcohol floating around the house.
The rubber pinch roller is another area of much debate on what to use. Some techs say use only rubber roller cleaner as anything else will dry the rubber out. Some say they have used denatured alcohol on them since dinosaurs roamed the earth and never had an issue. Me? I've been using the same rubbing alcohol since I made my first mixtape in the 1980's and never had an issue.
So, the textbook answer is use denatured alcohol on the heads and capstan shaft, use rubber roller cleaner on the pinch roller. My experience has been rubbing alcohol works just fine if you follow up with a dry cleaning after the rubbing alcohol. I still own some of the machines I had in the 80's and they are fine.
Step 4: Clean Here!
What to clean?
In the pics you will see a Q-tip pointing to each part you need to clean. Does it matter which way you scrub? Not really. I have found it easier to clean a pinch roller by scrubbing across the face of it in the same direction the capstan engages it.
On some machines you can actually get your hands into the mechanism and put a finger on the roller to keep it from moving while you clean a little bit at a time. On others you can barely get a Q-tip near it. If the machine has mechanical controls that engage even when the power is off, you can use this to put the machine in play. This will at least keep the roller from getting away from you as you scrub.
Some machines have removable doors as seen in the second to last pic. On home units, if the door does come off it's usually by giving the face of the door a light pull up and away from the rest of the door. Not all have removable doors. Close examination of the door when it's open will usually tell you if it's removable. You'll see they are two distinct pieces.
Removable doors are generally only found on middle to high end home units and on very old shoebox style portables. Few boomboxes had them and only pro type portables of later years had them.
How much to clean? On the heads and capstan, till no more brown stuff shows up on your moist Q-tip. On the pinch roller till no more BROWN residue comes off. Some rollers may shed black when being cleaned. This is because they are breaking down with age and there is nothing you can do about it. It may still give you months-years of service but it is going to eventually dry rot and crack or turn to soft goop.
The last pic shows you the dirty capstans on an auto reverse home deck. Auto reverse means the machine can play both sides of the tape without you manual flipping it. You have two pinch rollers and two capstans. There are also dual capstan non-auto reverse machines, you still clean both rollers and both capstans.
** a little cheat for those with good dexterity **
Some cassette decks will allow you to put them into play while powered on with no tape in them. This causes the pinch roller to contact the spinning capstan. If you are careful, you can get in there with Q-tip and use the rotating parts to your advantage. The downside to this is the Q-tip can get caught up in the spinning capstan shaft. Best case scenario, you hit stop and unwind the cotton from the capstan shaft. Absolute worst case is the Q-tip gets pulled in through the roller and you break something. If you choose to do this, be very careful.
What about demagnetizing?
It seems the jury is once again out on demagnetizing. Demagnetizing is using a special tool to remove any stray magnetic fields that may have accumulated on the tape transport. A magnetized transport will slowly erase tapes. Some folks are saying it's not needed unless the machine was worked on with magnetized tools, others say it should be done regularly. Demagnetizers are no longer easy to find and can do more harm than good if used improperly. If you really want to learn more about them search for the topic on tapeheads.net and you will surely get plenty of answers.
Step 5: What Shouldn't Be Seen.
What about damaged parts?
Now that you have cleaned up the tape path you can take a good look for damage. In pic 1 you see a good reflective shot of a perfect play/record head. The surface of a good head has no ridges. Ridges indicate wear. As the tape goes past the head, it does so under tension and eventually wears away at the head. A worn head will playback with poor highs or muddied sound.
In pic 2 I have pointed out a dimple on the roller. This dimple is caused by the recorder having been stored in the "play" mode. The roller was left pressed onto the capstan shaft for a long time. On a voice recorder, this dimple may not be a big deal but on a machine used for music, you will hear the dimple as a weird wavering of speed at a regular interval. There's no fix for the dimple other than roller replacement. Fortunately this problem is almost nonexistent on electronically controlled tape decks.
In pic 3 I pointed out the center of the heads and guides. The tape crosses the heads at the center, the guides are mainly there to prevent very poorly made cassettes from jamming things up. The guides will collect tape oxide in the corners and that should be cleaned.
On very old machines like the 1960's Norelco that's in pic 3, it's not uncommon for the heads to have a little weirdness on the edges. If its not in the tape path, it's not an issue. This is just leftover "flash" from the plastic machining. Plastic encased heads like those seen on early Philips / Norelco machines became uncommon as tape tech advanced.
What can be done about a bad roller?
The roller can fail in a few ways. It can harden and crack. It can soften and turn to goo. It can end up dimpled like the one in the pic. Dimpling isn't too annoying on a machine used just for voice but can be very annoying with music. A soft roller is on its way to turning into goo. This is just due to the rubber breaking down. The only fix is replacement. A hardened roller can sometimes be saved by removing it and soaking it in brake fluid for a few hours. This is a hail mary approach that *might* yield results and beyond the scope of this instructable. Don't confuse hardened with firm. The rubber roller should be firm like car tire rubber. A truly hardened roller is like rock and can even crumble if you mess with it.
A hardened roller will lead to tape skewing issues. This is when the tape wanders off it's intended path across the heads and gets crinkled by the guides. The crinkling eventually gets bad enough to jam things up and the machine will eat your tape. This is yet another good reason to do regular maintenance to your machines so you know how the heads and roller are doing.
Step 6: Different Machines, Same Stuff.
Here's some views of different machines. The first is a 1960's Norelco, The second an early 80's Toshiba portable (walkman). The third through fifth are of an early 1990's Technics double cassette deck with auto reverse. Note how despite several decades of difference, it's still the same basic parts to clean. Pic 4 shows the Technics with the door off. You can easily get to everything you need this way.
Step 7: Clean Machines Should Be Enjoyed!
Once all cleaned up don't be afraid to enjoy your machine and get it dirty again. Cleaning of a tape machine is considered regular maintenance. Enjoy your tapes but don't forget to clean more regularly when listening to cassettes made in the 60's and 70's or off brand stuff as they are just as bad.
Check out my instructables for more tape related articles. If you are looking for a forum of fellow tape enthusiasts, check out tapeheads,net.