Loud hum or roar when playing a cassette tape

Record/Play switches

This tip can apply to many different types of audio cassette tape recorders, from inexpensive classroom models to expensive stereo component decks. The one thing that all of these have in common is a mechanical record/play switch. Newer high-end cassette decks usually don't use mechanical switches these days, so this will not apply to them. Unfortunately it's nearly impossible to determine what type you have unless you have a technician look inside the unit, but the good news is that this won't hurt the newer type of deck, it just won't help.

Problem: Your cassette recorder is suddenly emitting a loud roaring sound, similar to feedback, when you attempt to play a tape.

Solution: This is a temporary fix that will let you get your cassette recorder to work for a short period of time and hopefully get you out of a jam. Take out the tape you are trying to play and insert a blank cassette tape (or one that hasn't had the record prevention tabs knocked out). Put your machine into Record mode and then hit Stop. Continue alternating from Record to Stop 5 to 10 times. Try playing a tape again and see if the problem is gone. If not, repeat the process. If it doesn't work after 2 attempts, it probably won't work at all. Also, if it does work, the problem is guaranteed to return again, possibly within minutes or hours of use. Either way, take the cassette recorder in for service and tell them you have a bad or dirty record/play switch and they should know what you are talking about. The repair may not be worth the cost on units costing less than $75.00.

Explanation: A mechanical record/play switch is merely a long switch containing numerous contacts capable of switching several separate circuits simultaneously. The contacts are made of silver or copper and are coated to prevent tarnishing. Unfortunately, tarnishing of the contacts will always occur eventually causing bad connections on the switch contacts. These contacts are responsible for switching your cassette recorder's circuitry from record mode to playback mode. When something goes wrong here, you get all kinds of interesting noises generated by the amplifier. By switching the machine in and out of record mode, the switch contacts are moved and scrape against each other removing some of the tarnish. If enough is removed, the unit will start working, but of course the coating is already gone and the contacts will tarnish again quickly.