Reviving a Norelco Philips Cassette Recorder From the 1960's

this instructable assumes that you have basic electronics skills and above average mechanical aptitude. disassembly and reassembly of a mechanism will be required and maybe simple soldering. instructions given here are tailored to early philips / norelco machines only.

a little history..

2013 marks the 50th anniversary of the compact cassette, known as "cassette" by most folks. few consumer products have a 50 year run. in it's 50 year lifespan, the cassette dethroned the reel to reel as a portable consumer audio recording media, made taking your music with you a convenient reality, spawned the birth of the walkman, and thus the creation of the portable entertainment industry as we know it. all this caused by a lowly cassette recorder brought to market in 1963 by the philips company.

in europe, these early cassette recorders were sold under the philips name. in the USA they were sold under the norelco name. philips was sued by philco and couldn't use the philips name in the american market. philips / norelco = same thing, different market.

initially, philips / norelco machines where the only ones on the market but eventually other brands started showing up. its not uncommon to find early recorders of this type that had a philips mechanism inside and a different brand name on the outside. 

in the first pic you will see the underside of three old philips based recorders. those machines from left to right are norelco, telefunken, norelco. the first two are the later models. the machine on the right is one of the very early models. note on the first two there is a small circuit board on the bottom left of each machine. that is the speed regulator board. the earliest of machines didn't have them and were more prone to speed variations.

that little board makes a huge difference in their ability to be used for any reasonable playback of music. the earliest machines lacked this board thus making them only suited for voice at best. speed fluctuations are common with all early cassette portables but its particularly bad with the earliest philips machines that lacked that regulator board.

as mentioned earlier, some manufacturers used a philips chassis in their own housing. despite the different external appearances, there's some notable traits all philips machines have that can help you ID what mechanism is really lurking in that old cassette recorder. the pics show you these traits.

1) all early philips machines have 2 DIN plugs for audio in / out
2) all early philips machines use one control lever that moves front / back and left / right
3) all early philips machines use 5 C batts
4) all early philips machines have two volume controls, one for playback and one for record level
5) it seems that the earliest of the actual philips / norelco branded machines did NOT have a tape viewing window in the door. these very early machines are of historical importance as being the first of their kind in the world but they are also the ones that lack the speed regulator board. this rule doesn't apply to re-branded machines. ampex for example offered the micro 10 which had a solid black door and the voltage regulator board.

a word of advice..
hopefully you are wearing clothes you don't care about! it's also a good idea to find a junk towel and relocate machine onto junk towel to protect your work area.

from what on gods earth you may ask? what can this humble tape recorder contain that is so vile it requires special instructions bordering on hazmat training?

melted belt goo

go ahead.. laugh. laugh all you want. by the end of the instructable i'll be laughing at you if you did not heed my warning. melted belt goo has an incredible ability to get on everything. its a sticky tar like substance disguised in the shape of a tape recorder belt. it will get on your tools, hands, clothes, floor, etc if you aren't careful. consider yourself warned.

resist the temptation to power the machine up. you'll likely be wasting your time. the original belts on these old machines have turned to goo and the reason why we need to get inside to repair it. there are some slight variations but all these machines are taken apart in a similar fashion.

the transport control knob must be removed. on the very early machines, its just a plastic knob that pops off. on the later generation machines, the control knob pops off with a metal piece still attached to it. see the pics. in both cases some careful prying is all that needed to get it to come off.

in the cassette well (area where cassette is inserted) there will be one screw in the center, remove it. flip machine over and you will find one or two screws holding the bottom cover. the early machines used two screws. removing those screws will cause bottom cover and battery door to come off.

this is where you may find your first bit of breakage. the battery door on these machines apparently stumped lots of folks. its not uncommon to find the bottom cover broken at the screw hole because somebody was trying to pry the cover off in an attempt to get to the batteries. if your machine has tape holding the bottom, the bottom screw turret has been busted off. see pic.

bottom cover is off? locate the screws holding the chassis to the plastic shell. on the early machines they are in the 4 corners, on later machines it's slightly different. the two by the control lever are in the same place but there may be only one at the other end somewhat centered.

you should be able to wiggle the chassis in the plastic shell once all the screws holding it in place are out. the chassis will lift out. lifting the opposite side from the DIN plugs first makes for easier removal.

the achilles heel of all old tape recorders seems to be melted belts. the black rubber used in these belts becomes unstable and melts. the stuff gets on everything it touches and like a bad case of the flu, spreads over everything if you're not careful.

just an example..
black goo gets on screwdriver, screwdriver gets laid down on bench, goo gets on bench, you rest your arm on bench, goo gets on arm that later rubs on your shirt.. and so it begins.. god forbid you unknowingly drop a piece of the semi melted belt on the floor and then roll over it with your chair. that becomes a real mess.

its EXTREMELY important that for this part you work as if you're a surgeon working on a highly contagious patient.

once the lid is off you will see inside the machine. melted belt goo can be on the inside covers, on the vinyl battery flap, and on the mechanism itself. when setting down the lids, make sure there's no melted belt goo on them. the battery flap is black and its hard to see. if in doubt, set the lids down on a paper towel.

you will likely find melted belts on the pulleys and motor. that's normal. take a careful look around the inside of the machine and make sure no bits of melted belts are laying in the chassis or in the plastic shell. these are the bits that end up on the floor unknowingly causing a major mess. you can pluck them out using needle nose and a paper towel to wipe off the melted goo you just got on the pliers.

the plastic shells can be cleaned with creme style Go-Jo mechanics hand cleaner. it works amazingly well for this. it will dissolve melted belt goo easily. for the pulleys and internal metal parts there are a number of documented choices. windex, mineral spirits, acetone, goof-off, etc. all chemicals have their good points and bad. some will attack the plastic used in the machine so be very careful.

my cleaning chemical of choice? goof-off.
goof-off has a strong chemical smell so work somewhere with good ventilation. it will attack some plastics but i have found it doesn't affect good rubber parts nor nylon like whats used in tape recorder pulleys. this is solely my experience. i am not a chemist.

i use goof-off and a bunch of q-tips to get all the melted rubber off the machines internals. this is a messy and time consuming job. you will go through LOTS of q-tips. make sure to get the goo out of the V cut in the pulleys.

the motor is housed in a square metal box. to get to its pulley, you must remove a simple cover. the cover has one screw. inside the cover will be one or two pencil eraser sized rubber spacers. those are important. they keep the motor lined up properly in the can. if your spacers are melted or missing, you must make up some spacers out of foam rubber or any suitable material.

check your battery contacts. this machine uses 5 C batts. make sure all the contacts are free from corrosion. if corroded, a brass bristle brush is good for cleaning them up. in the battery compartment there will be a paper tag with your machines model number if you are curious.

there are two rubber drive wheels on the top side and one on the bottom side that must be cleaned. i have yet to see one of these melted but they do get glazed or melted belt goo on them. they can be cleaned by soaking a q-tip in goof-off and gently spinning the wheel while holding the q-tip against the rubber edge. when the q-tip stops coming up covered in black stuff, its clean.

on the top side you have a rubber roller called a pinch roller that must be cleaned. these are often caked with rust colored residue from old tapes. clean it the same way you just cleaned the rubber drive wheels. 2nd pic is of dirty roller, 3rd pic is of clean roller.

finally the heads and capstan shaft must be cleaned. this can be done with alcohol and a q-tip. the heads are the two plastic rectangular parts in pic 2 with the wires going to them. the one in the middle is the play / record head. the one on the right is the erase head. technically you are supposed to use only denatured alcohol for this. rubbing alcohol will work but make sure to wipe head with dry q-tip when you are done cleaning it. any residue here will appear rust colored.

the capstan shaft is the metal shaft that the rubber roller presses against. any residue on that will appear as rust colored.

all machines need an oiling at some point.

here you will be applying a tiny amount to the areas pictured. these are the contact surfaces of the slide mechanism and the capstan shaft. you will also need to get a tiny drop into the pulley shaft end of the motor. you should oil the other end but i will leave that judgment call to the reader. the wires to the motor may not take well to being pulled out and reinserted.

when oiling the motor and capstan shaft, put your drop of oil on there, spin the part and wiggle it a bit, then take a clean q-tip and soak up any extra oil so it doesn't get on your belts later. clean the capstan shaft with an alcohol dipped q-tip when you are done oiling so you dont acidently get oil on your tapes.

this machine has two belts. one is critical, one is not. the longer belt that wraps around the large metal pulley and the large nylon pulley is the critical one. you can NOT use a rubber band here. you need a real belt. the second belt is a smaller one that drives the tape hubs. you can get away with a rubber band here but it wont last as long as a real belt.

the belts on this machine are square cut. stick with that. once again the smaller one isn't as critical to tape speed so i used what i had but that belt really is a wee bit too thick. in choosing a correct sized belt from an assortment, find a belt that fits but isn't tight like a banjo string. it should be tight enough to present good resistance to slippage but not so tight that its binding up the mechanism.

belt routing is pictured. to get the belt over the flywheel you must remove the metal retainer plate that is pictured. this plate must go back on when you are done as it keeps the pulley lined up.

where to get belts? i like to purchase an assortment cassette deck belt kit from ebay as that gives me enough belts to fix several machines.

got your belts on? all clean? all lubed? put it all back together. these machines are fairly robust and all except one i have worked on have been easy fixes. drop some batteries and a known good cassette in and lest see if she works.

to play, push play lever towards tape. volume control is knob closer to tape. you should hear music if all is well and your tape is good.

possible issues and their solutions..

low audio - there is a (fortunately) easy to get to cap on the edge of the board in one of the pics below that sometimes goes bad. its an audio coupling cap. you can test if that's your problem easily by just jumpering a suitable cap onto the board traces. note polarity. + is side closer to board edge. if audio comes up with jumpered cap, you need to desolder and replace that cap. there isn't enough room to just add it under the board and that's ghetto! the cap is usually a 40uF at like 10v. its soo easy to get to, might as well replace it if in doubt. see pic 1.

rubbing noise when machine runs - the flywheel cover on some of these machines had a poorly designed shim that rubs on the flywheel instead of just the bearing point. you will need to sand away part of the shim so that the bearing point contacts it but not the flywheel. be careful doing this. the part you need to sand happens to be the part that holds the plastic shim in place. see pic 2.

improper play speed - if you have a machine with a regulator board, this may be an easy fix. if you have a very early machine, tough luck. you'll just have to deal with it or only play tapes recorded on your particular machine. for machines with the regulator board, there is a small potentiometer on the board that may have paint on it. this is the speed control. you can tweak that with a known good tape and a fresh set of batteries and get your speed about right. see pic 3.