How to choose proper cassette belt
Eli Luong
of the larger cables that connectors to the motor is broken). I
measured it to be about 20cm or 8in. I found this website for parts:
http://www.studiosoundelectronics.com/cassette.htm
But I'm not sure what to choose exactly. They said to account for
stretch (measured the 20cm w/out stretch), but then they have 1) flat
belts, 2) square belts, 3) square belt small types. From what I can
see on my broken belt, it appears to be square shaped, 1mm in
diameter. Any guidance, please?
Thanks,
- Eli
mm
If you think it's square, it's probably square. If it measures 1mm,
it probably is.
I've had to replace one or both belts on my phone machine every 8
years or so. It uses a square belt also, less than 2mm iirc.
I couldn't get the original width, so I got the next size bigger. No
problem. It never slippped off the pully, although I'm sure if it was
wide enough it would.
I've probably gotten about 10% shorter than the measured length, and
like I say it lasts about 8 years. They sell them, or used to, at a
store here, but I ended up buying two the last time, I guess because I
thought the second belt would fail too.
Maybe if I bought shorter, it would have enough tension to last
longer, but I think it might stretch out even sooner.
Now this machine uses microcassettes and there isn't much drag on the
wheel it has to turn, even when the cassette is in place. I wonder if
you are using full size cassettes, if that would make a difference.
It might need more tension to keep the belt from slipping??? See how
hard it is to turn when the cassette is in place. Still, I don't
think I'd go below 85% of the measured length, probably measured on
the stretched out/broken belt.
The belt manual at the store gave a guideline, and it's been 18 years
since this started, but it might have said 10 to 15% shorter. Does it
say anything on the webpage you're looking at.
Right now I'm using another machine from about the same date, 1984. I
got it on ebay 2 years ago. I don't know if the belt has been changed
or not, but surely it must have been.
http://www.pyramidbelts.com/calc_beltlength.php gives a belt length
caluculator, but I don't know for what size belts.
It says "Enter stretch percentage desired (7.5, 10, 12.5%, etc.)"
I see that some are in the range our machines use.
http://www.pyramidbelts.com/fbelts.php
Arfa Daily
"mm" <NOPSAM...@bigfoot.com> wrote in message
news:j9aik5p6c9ipntakn...@4ax.com...
> On Sat, 9 Jan 2010 16:49:39 -0800 (PST), Eli Luong
> <elil...@gmail.com> wrote:
>
>>Hello - I am trying to repair a broken cassette player (dual-deck, one
>>of the larger cables that connectors to the motor is broken). I
>>measured it to be about 20cm or 8in. I found this website for parts:
>>http://www.studiosoundelectronics.com/cassette.htm
>>
>>But I'm not sure what to choose exactly. They said to account for
>>stretch (measured the 20cm w/out stretch), but then they have 1) flat
>>belts, 2) square belts, 3) square belt small types. From what I can
>>see on my broken belt, it appears to be square shaped, 1mm in
>>diameter. Any guidance, please?
>>
>>Thanks,
>>- Eli
>
> If you think it's square, it's probably square. If it measures 1mm,
> it probably is.
>
> I've had to replace one or both belts on my phone machine every 8
> years or so. It uses a square belt also, less than 2mm iirc.
>
> I couldn't get the original width, so I got the next size bigger. No
> problem. It never slippped off the pully, although I'm sure if it was
> wide enough it would.
This is not a problem with a telephone answering machine, where speed is not
important, but it is with an audio cassette deck. It is especially a problem
if it is a dual deck machine, but driven by a single motor. If both belts
are not the same dimension across the section, then one deck will run at a
different speed to the other. Even a small discrepancy can cause a
significant speed error. As far as picking a size goes, many belt
manufacturers quote the sizes as a diameter when the belt is made into a
nice circle. I have a chart with many concentric circles on it, each marked
with a diameter. The size to pick is the next one down from where the belt
sits on the chart. Most cassette decks don't mind too much if the belt is
slightly tight, and in general, better that than loose, but it doesn't want
to be so tight that you have to really stretch it to get it on, as this can
rapidly cause bearing wear, and stop idler arms from swinging, where these
rely on light belt tension to form their spring return.
Arfa
<snip>
Eli Luong
> This is not a problem with a telephone answering machine, where speed is not
> important, but it is with an audio cassette deck. It is especially a problem
> if it is a dual deck machine, but driven by a single motor. If both belts
> are not the same dimension across the section, then one deck will run at a
> different speed to the other. Even a small discrepancy can cause a
> significant speed error. As far as picking a size goes, many belt
> manufacturers quote the sizes as a diameter when the belt is made into a
> nice circle. I have a chart with many concentric circles on it, each marked
> with a diameter. The size to pick is the next one down from where the belt
> sits on the chart. Most cassette decks don't mind too much if the belt is
> slightly tight, and in general, better that than loose, but it doesn't want
> to be so tight that you have to really stretch it to get it on, as this can
> rapidly cause bearing wear, and stop idler arms from swinging, where these
> rely on light belt tension to form their spring return.
>
> Arfa
>
> <snip>
Thanks. It does look like it's driven by just one motor. What you said
suggests I would have to change both belts at the time time, in order
to keep the cassette decks running at the same speed? If I change both
belts, and it differs a little bit, would that mean I would have to
readjust the speed of the motor? The service manual for the shelf
stereo mentions speed adjustment of the tape deck.
- Eli
hr(bob) hofmann@att.net
>
> - Show quoted text -
Unless the belt actually is slipping, the belt size does not effect
the actual speed.
Rheilly Phoull
"Eli Luong" <elil...@gmail.com> wrote in message
news:4f4de5d5-a662-4350...@h9g2000yqa.googlegroups.com...
- Eli
If you have it down it would be foolish not to replace both belts since they
are the same age presumably and to avoid doing the job again when the older
one fails.
--
Regards .............. Rheilly P
Eli Luong
>
> Thanks. It does look like it's driven by just one motor. What you said
> suggests I would have to change both belts at the time time, in order
> to keep the cassette decks running at the same speed? If I change both
> belts, and it differs a little bit, would that mean I would have to
> readjust the speed of the motor? The service manual for the shelf
> stereo mentions speed adjustment of the tape deck.
>
> - Eli
>
> If you have it down it would be foolish not to replace both belts since they
> are the same age presumably and to avoid doing the job again when the older
> one fails.
> --
> Regards .............. Rheilly P
Good point! I just have to find a local place that sells some of this
stuff...
mm
That seems right to me. If there is no slippage, the speed of the
motor and the size of the two pulleys seem like the only things that
control the speed of the driven wheel. An even more extreme case is
a bicycle chain where there can be plenty of slack on the bottom, but
the top is tight.
But maybe Arfa can explain it to me.
hr(bob) hofmann@att.net
> On Sat, 9 Jan 2010 20:46:07 -0800 (PST), "hr(bob) hofm...@att.net"
>
> - Show quoted text -
EXACTLY!!!
Michael A. Terrell
I found this place the other day: http://www.turntableneedles.com/
They appear to use the old PRB measuring system. PRB had a cross
refference by brand and model number. Check and see if thay have updated
it to include your unit.
I've never dealt with them, but finding belts is getting harder and
harder. Most of the old suppliers are out of business.
--
Greed is the root of all eBay.
David
<d0175230-4dad-4108...@j5g2000yqm.googlegroups.com>,
Eli Luong <elil...@gmail.com> wrote:
Dick Smith Electonics (DSE.com.au) sell a package of belts of varying
sizes - probably will be one in the package that suits
David
Mark Zacharias
news:eb7be913-0fab-4a5f...@u7g2000yqm.googlegroups.com...
If it's square-cut it does. Seen it many times.
Mark Z.
Arfa Daily
The size of the belt section *does* matter. If one belt is of smaller
section than the other, they will ride at different points on their drive
pullies and capstans. This effectively alters the diameters of the pullies
with respect to one another, making one deck run at a slightly different
speed to the other. It's not a lot, granted, but certainly enough to hear,
and most definitely enough to see on a speed-test strobe tape. Sometimes, if
not using manufacturer's original belts, there is no option but to use
different section-size belts on the two decks in order to get the correct
length-sizes. When this is the case, any speed differences can be removed
enough to not hear them, by adjusting the motor speed such that one deck is
running very slightly slow, and the other very slightly fast. All this of
course, refers *only* to dual decks driven by a single motor - for instance
the hundreds of Aiwa models with the three and five CD carousel units in the
top, that were popular barn items a few years back. Where each deck is
driven by its own motor, then the speeds can be set independantly.
Whenever a main drive belt is replaced on any cassette deck, the speed
should be checked anyway, purely as a matter of good and professional repair
practice ...
Arfa
Arfa Daily
"Rheilly Phoull" <rhe...@bigslong.com> wrote in message
news:U-OdnfADrOHR-tTW...@westnet.com.au...
Agreed, and see my reply to Bob further up the thread
Arfa
Arfa Daily
"Mark Zacharias" <mark_za...@sbclobal.net> wrote in message
news:00a8bb53$0$8158$c3e...@news.astraweb.com...
Thanks, Mark :-)
Arfa
Arfa Daily
"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
news:_8udnUFFMdc3gNfW...@earthlink.com...
Same this side of the pond. I have a row of probably 30 nails in the wall at
the back of the bench, each marked for a different size of drive belt, with
the smaller sizes going up in one and two mm steps. I used to be able to
keep these stocked from several suppliers without any problem at all. Now
there are only a couple that keep them, and as they run out of stock of any
size, they do not seem to replace them - or maybe they can't obtain them
themselves. I would guess that at least a third of my nails are now either
empty, or down to one or two belts from the ten minimum that I used to keep
...
Arfa
Sansui Samari
> "Michael A. Terrell" <mike.terr...@earthlink.net> wrote in messagenews:_8udnUFFMdc3gNfW...@earthlink.com...
I wonder how difficult it would be to produce rubberized belts.
Anyone know if they were mold injected or extruded and joined at the
ends, or anything about the process. I work in a mold injection plant
right now, so even if it's not feasible, it would still be interesting
for me, to know the process.
mm
And indeed, you convinced me. Thanks.
Arfa Daily
<snip>
>>>>
>>>>Unless the belt actually is slipping, the belt size does not effect
>>>>the actual speed.
>>>
>>> That seems right to me. If there is no slippage, the speed of the
>>> motor and the size of the two pulleys seem like the only things that
>>> control the speed of the driven wheel. An even more extreme case is
>>> a bicycle chain where there can be plenty of slack on the bottom, but
>>> the top is tight.
>>>
>>> But maybe Arfa can explain it to me.
>>
>>The size of the belt section *does* matter. If one belt is of smaller
>>section than the other, they will ride at different points on their drive
>>pullies and capstans. This effectively alters the diameters of the pullies
>>with respect to one another, making one deck run at a slightly different
>
> And indeed, you convinced me. Thanks.
... No probs. A good example just occured to me. Do you remember the "DAF
Variomatic" auto transmission ? This was a belt-drive system able to provide
continuously variable 'gear' ratios by squeezing the sides of the pullies
together or allowing them to part differentially, which altered the point at
which the belt 'rode', effectively altering the ratio of one pulley
diameter, to the other.
see http://www.youtube.com/watch?v=R8AzqtomwD0
Arfa
Chuck
<elil...@gmail.com> wrote:
A word of caution. We discovered years ago that using PRB square
belts would greatly increase the deck's wow and flutter so I would
avoid them. Chuck
Michael A. Terrell
PRB has been gone for a long time. They were bought by Russell
Industries.
Mark Zacharias
Yes, but they still have the "PRB Line" and that product looks the same.
Trouble is, there are fewer and fewer choices for replacements these days.
Mark Z.
mike
I can't tell if it's relevant here, but...
The dual-capstan cassette player I had used capstan pulleys
of different diameter. In order to keep the capstans at the same speed,
the belt had to stretch on one side of the pulley more than the other.
That amount of stretch determined the tape tension.
In that case, the amount of stretch in the belt might be considered
an important parameter.
Michael A. Terrell
That is supposed to be the remaining inventory from purchasing PRB.
> Trouble is, there are fewer and fewer choices for replacements these days.
Yes. I miss the Oneida belt kit I had back in the mid '70s. It had
rolls of various belt stock and a cutting jig to make custom belts.
>
> Mark Z.