Where is the best place to find a replacement belt for a cassette tape mechanism? I am currently trying to repair a 1980s boombox with a slipping belt. Specifically, the belt I need is a 3 and 1/4 inch diameter belt that is about 1 millimeter thick.

The term to search is "square section belt 1mm" (then look for the closest match on length). I tried and quite a few retailers of those showed up, so go through them.... And warm 80s cheers for restoring some 80s goodies

eBay should have those 1mm square belt sets for fairly cheap. However, they seem to be pretty hit or miss as it seems like some of them have really bad wow and flutter characteristics.

For the component cassette decks I prefer ordering the model specific kits instead.

Fix Your Audio is pretty good for cassette deck parts too. I've ordered a pair of odd sized pinch rollers from them last year. I believe they also have belts too.

A cheap fix for a belt that's still intact but only just barely slipping is to get some 90% isopropyl alcohol and clean the belt path and pulleys as well as the belt itself. Doing so might improve the grip just enough to work. However if a belt is available I would just replace the belt. Make sure to still clean the belt path and pulleys though.

eBay should have those 1mm square belt sets for fairly cheap. However, they seem to be pretty hit or miss as it seems like some of them have really bad wow and flutter characteristics.

For the component cassette decks I prefer ordering the model specific kits instead.

Fix Your Audio is pretty good for cassette deck parts too. I've ordered a pair of odd sized pinch rollers from them last year. I believe they also have belts too.

A cheap fix for a belt that's still intact but only just barely slipping is to get some 90% isopropyl alcohol and clean the belt path and pulleys as well as the belt itself. Doing so might improve the grip just enough to work. However if a belt is available I would just replace the belt. Make sure to still clean the belt path and pulleys though.

For the isopropyl alcohol fix, will the alcohol destroy the belt in any way?

The term to search is "square section belt 1mm" (then look for the closest match on length). I tried and quite a few retailers of those showed up, so go through them.... And warm 80s cheers for restoring some 80s goodies

Thank you! I put a rubber band in there (very temporary) now but I still want to get a belt. I love the look of the boombox I am restoring so I just had to restore it!

For the isopropyl alcohol fix, will the alcohol destroy the belt in any way?

I've personally never had problems cleaning my belts and pinch rollers with it but I guess it also depends on the composition of the belt. Some seem to just melt over time regardless of if you cleaned them with alcohol or not.  

I've read on audio forums that some people also try to boil the belts to get them to shrink a bit, never tried that one myself.

With most cassette mechanisms I find getting to the belts is enough of a PITA that I usually just replace all of them at once.

I would be worried about belts from unknown source - Some might contain plasticizers that could diffuse into the machine's pulleys (which are probably made of Plastic) over the place where the belt touches the pulley, and basically melt the pulley. Rubber bands are often made of rubbers that also do the same reaction, so i'd remove the band immediately. Proper belts are made of materials that won't do this

If the band is only a little loose, you can also try to turn it inside-out

I've personally never had problems cleaning my belts and pinch rollers with it but I guess it also depends on the composition of the belt. Some seem to just melt over time regardless of if you cleaned them with alcohol or not.  

I've read on audio forums that some people also try to boil the belts to get them to shrink a bit, never tried that one myself.

With most cassette mechanisms I find getting to the belts is enough of a PITA that I usually just replace all of them at once.

With the boombox I'm working on, the belt can be replaced just by taking out the cassette mechanism and looking around the back. It only has that one belt (The rest is done by gears), which is a great design in my opinion. It's also an auto-reverse deck so it's very complicated. However, the cassette mechanism itself is a pain to get out because the tuner/graphic equalizer assembly has to come out first. The boards on said assembly use these real PITA connectors to connect to the main board. They are almost like the stab in connections on wiring devices! At least the cassette mechanism itself uses normal connectors.

I would be worried about belts from unknown source - Some might contain plasticizers that could diffuse into the machine's pulleys (which are probably made of Plastic) over the place where the belt touches the pulley, and basically melt the pulley. Rubber bands are often made of rubbers that also do the same reaction, so i'd remove the band immediately. Proper belts are made of materials that won't do this

If the band is only a little loose, you can also try to turn it inside-out

I figured there would be at least one thing wrong with those cheap Chinese belts. Where should I get belts that I can be sure do not contain plasticizers?

You may look on ebay to find packs of assorted belts. Cannot guarantee they are high quality but they should do the trick and you can just replace them again in the future before they degrade.

Side note; anyone who is interested in older audio equipment and sources, give Techmoan a search on youtube. He reviews and services all the iolder forms of audio formats and players.

Don't laugh--if a belt can't be found---try an equivalent sized rubber band.Did this with a radio station cart machine-capstan drive belts.Used several rubber bands from the secretarys desk-the station didn't have spares-and the machine was fine!

While I haven't ordered belts from them, the pinch rollers I ordered from the Fix Your Audio site are still working great. I believe they're made in Europe too.

Yeah Techmoan is a great channel for those interested in older audio gear.

You may look on ebay to find packs of assorted belts. Cannot guarantee they are high quality but they should do the trick and you can just replace them again in the future before they degrade.

Side note; anyone who is interested in older audio equipment and sources, give Techmoan a search on youtube. He reviews and services all the iolder forms of audio formats and players.

Apparently according to Ash, some cheap belts may contain plasticizers. By the way, I love Techmoan!

Apparently according to Ash, some cheap belts may contain plasticizers. By the way, I love Techmoan!

Actually all of them. Even the true rubber ones (glycerine). So all will degrade over time, sooner or later. It mainly depends on the storage environment (small sealed bag may slow down the plasticizer evaporation significantly, so does low storage temperature).

Actually all of them. Even the true rubber ones (glycerine). So all will degrade over time, sooner or later. It mainly depends on the storage environment (small sealed bag may slow down the plasticizer evaporation significantly, so does low storage temperature).

So all belts will degrade the pulleys in the cassette deck at some point?