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Aiwa F770 cassette from 1985

N

N Cook

Jan 1, 1970
0
b said:
N Cook ha escrito:

I don't understand. have you replaced the belts with new? if so,
nothing should be falling off and nothing will need modifying.

-B.

both new bands and cleaned pulleys. moving from REW to play causes the band
to fall off, presumably due to a snatching / breaking / imbalance associated
with this double connection to the tape presumably at take up.
If I put in a guide then it can't fall off and will presumably self centre
back up the vague hump on the periphery of the "reverse" flywheel.
On baluster/ bulbous motor pulleys they usually have a preventer disc either
side of the bulging active part. This pulley has a larger pulley on one side
but nothing on the other in the way of a preventer.
 
B

b

Jan 1, 1970
0
N Cook ha escrito:
both new bands and cleaned pulleys. moving from REW to play causes the band
to fall off, presumably due to a snatching / breaking / imbalance associated
with this double connection to the tape presumably at take up.
If I put in a guide then it can't fall off and will presumably self centre
back up the vague hump on the periphery of the "reverse" flywheel.
On baluster/ bulbous motor pulleys they usually have a preventer disc either
side of the bulging active part. This pulley has a larger pulley on one side
but nothing on the other in the way of a preventer.

Hmmm....if thers no sign of there having being a preventer in the
past, i'd be inclined to think that the belt is not the correct
replacement - too slack?? It should be albe to withstand the change
of tension without slipping or wandering.
-B.
 
N

N Cook

Jan 1, 1970
0
b said:
N Cook ha escrito:

Hmmm....if thers no sign of there having being a preventer in the
past, i'd be inclined to think that the belt is not the correct
replacement - too slack?? It should be albe to withstand the change
of tension without slipping or wandering.
-B.

No signs of any preventers removed.
I think its the other way round. The one I replaced it with was a bit too
short/tight as you would normally do, it is probably highly critical. The
problem point is at moment of power switch on so the trailing pulley is
static, so inertial slack in the belt . The force in the belt to pull it
down the vague hump is higher than the differential force at the hump to
push it to the maximum part of the hump it would seem. If it rides down
initially to the axial paired larger pulley then no trouble but if it goes
the other way it falls off.
 
R

Ron(UK)

Jan 1, 1970
0
N said:
No signs of any preventers removed.
I think its the other way round. The one I replaced it with was a bit too
short/tight as you would normally do, it is probably highly critical. The
problem point is at moment of power switch on so the trailing pulley is
static, so inertial slack in the belt . The force in the belt to pull it
down the vague hump is higher than the differential force at the hump to
push it to the maximum part of the hump it would seem. If it rides down
initially to the axial paired larger pulley then no trouble but if it goes
the other way it falls off.

Have you checked for slight wear in the bearing of the shaft with the
barrel shaped pulley? Is the new belt the same width as the old one?

Ron(UK)
 
N said:
both new bands and cleaned pulleys. moving from REW to play causes the band
to fall off, presumably due to a snatching / breaking / imbalance associated
with this double connection to the tape presumably at take up.
If I put in a guide then it can't fall off and will presumably self centre
back up the vague hump on the periphery of the "reverse" flywheel.
On baluster/ bulbous motor pulleys they usually have a preventer disc either
side of the bulging active part. This pulley has a larger pulley on one side
but nothing on the other in the way of a preventer.

I've come across this one occasionally, and have fixed it by adding a
fixed guard each side, not by the drivewheel but beside the belt close
to where it goes onto the wheel. That way the belt momentarily
impacting the guard does not cause problems, and steers it properly on
the wheel.

I dont know why or how this can happen, but the fix works.


NT
 
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