Shortening stretched flat belts, cheap fix

Boombox open with a flat belt, that's otherwise in good condition, but stretched? Out of money? Shops closed? In a hurry? Need it playing asap?

I've tested this method and it works good enough.

What you need:

1. Stretched belt
2. -Sharp- knife/blade
3. Super glue (liquid, good quality)
4. Fine grit sandpaper (800-1200)
5. Flat smooth surface, for example a box cutter blade
6. Nerves

Start by making a rough estimate of how much the belt needs to be shortened to engage properly. Cut out the estimated amount, straight section.

Make a deep V shaped cut to one end. Duplicate it to the other end. Take your time and try to be as exact as possible.

Clean the belt with a good solvent/cleaner that leaves no residue. You can also sand the cut edges to get a bit more grit.

Now put the belt ends on a smooth surface and make sure they match. Apply evenly a small amount of super glue to the other end and carefully put the ends together on the surface, so you end up with flat as possible result.

Press the ends together with some force and hold on for some time. If the qlue sticks to the surface, use a knife to carefully carve it out.

No you should have the ends securely attached. Next thing to do is to sand out the glue from both sides so it wont make a slippery/hard section.

Once the sanding is finished and the ends are smooth, you can go ahead and test. I had to do this two times before I got it tight enough.

This method was tested on a Sony CFS-77L and the wow & flutter seemed to be just fine after the fix.

Or... how about just order the right size belt, wait a few days and get it fixed PROPERLY?

totally agree with superduper

Yeah i don't think this is a useful fix, I would rather wait a day and order the correct belt. Just because your ears don't pick up any w and f does not mean it's not there.

Just measured how stable 3000Hz stays. I used a Maxell XLII-S 90, these are the most "torque hungry" cassettes I own. I recorded about 2+ minutes of 3000Hz (actually 2950 Hz, because the Sony plays a bit faster, around +1,7% if I got the numbers right). I used Denon DRM-800A for recording.

The result from Sony was for most part, 2996-2999 Hz, minimum-maximum 2995-3001 Hz and peak values that I observed just one or two times were 2992-3002 Hz.

Looking at many service manuals, the acceptable output frequency range when adjusting motor speed can be quite wide.
For example (Sharp GF-575) 2985-3015 Hz (deck 1) and 2970-3000 Hz (deck 2). I think those can't be the acceptable variance/wow.

Denon DRM-800 service manual says that @ 3000Hz, a range of +-6 Hz is acceptable.

Looking at the peak values, Sony with the superglued shortened flat belt had it at +-5 Hz.

I am new to measuring things on cassette machines, but well, gotta start somewhere.

Appreciate your efforts but just buy new ones not worth the hassle .

but i understand sometimes you are fixing a mech
Cant wait
this could help to get the deck going
you need something to turn stuff
later you can order the belt
I know like most one day is a long time when the guts are on the kitchen table
and the woman is like WTF
I give this the thumbs up

I think it's a great idea I mean they make repair kits for cassettes , sometimes I don't feel like going through all the b******* ordering belts and waiting especially if I know I can fix it on the spot all these goddamn boxes waiting to break anyway so what the f***.

The only useful application for this hack is when you are trying to sell your radio on eBay and don’t mind scamming a buyer. The small $$ for a belt can’t possibly be worth the effort described above except for the cheapest of Scrooges. Heck I’ll bet it’s possible to reconnect torn panels of paper towels (or torn toilet paper) with saliva. But would you do it? And while it’s simple to say this is just a temporary stopgap, anyone ever did something to a box intending for it to be temporary but then forget about it or just didn’t want to reopen the box so it becomes permanent?

Not a good way!

Will only work with rubber in good condition. I suggest you use a new belt and cut to size. Works fine.