Author Topic: New belts for cassette tape mechanisms  (Read 894 times)
Medved
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Re: New belts for cassette tape mechanisms « Reply #15 on: October 05, 2020, 10:52:42 AM » Author: Medved
Not the pulleys. I was mainly pointing out all belts have component which evaporates and then once gone, the belt start to harden and crack.

For the pulleys the rubber is safe - the glycerine is inert towards most often used plastics (not aware about any where it would make problems). Don't count the residues of the degraded belt material "gluing" itself to them, but that is possible to clean out.
With other materials it is indeed a compatibility issue. But there materials like PTFE or to some extend Nylon are quite good for the pulleys - they are extremely inert against a lot of chemicals (mainly the PTFE), so do not suffer from the belts.
Cheap PVC is indeed problematic, but mainly with wire insulation (softened PVC, so containing plasticizers especially designed to soften the PVC), not seen belt material aggressive towards them to an extend it would affect the function. Even contrary, some plastic designs tend to start cracking once the plasticizer from their material evaporates (some cogs on small motors tend to break,...).
Most tape or phono mechanic designs do not require that high forces, so not completely hardened so brittle material is in fact a plus.
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Fluorescent05
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Re: New belts for cassette tape mechanisms « Reply #16 on: October 05, 2020, 11:14:19 AM » Author: Fluorescent05
Not the pulleys. I was mainly pointing out all belts have component which evaporates and then once gone, the belt start to harden and crack.

For the pulleys the rubber is safe - the glycerine is inert towards most often used plastics (not aware about any where it would make problems). Don't count the residues of the degraded belt material "gluing" itself to them, but that is possible to clean out.
With other materials it is indeed a compatibility issue. But there materials like PTFE or to some extend Nylon are quite good for the pulleys - they are extremely inert against a lot of chemicals (mainly the PTFE), so do not suffer from the belts.
Cheap PVC is indeed problematic, but mainly with wire insulation (softened PVC, so containing plasticizers especially designed to soften the PVC), not seen belt material aggressive towards them to an extend it would affect the function. Even contrary, some plastic designs tend to start cracking once the plasticizer from their material evaporates (some cogs on small motors tend to break,...).
Most tape or phono mechanic designs do not require that high forces, so not completely hardened so brittle material is in fact a plus.
Good, I don't think my good 80s boombox is cheap at all.
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Ash
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Re: New belts for cassette tape mechanisms « Reply #17 on: October 05, 2020, 04:38:40 PM » Author: Ash
To make it clear, all plastics contain plasticizers. (Without them, they would become something that looks similar to UV-damaged material that crumbles to dust). The problem is with some types of plasticizers used in cheap bands, which may not stay in place but could diffuse from the band to the pulley through the contact surface between them
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Fluorescent05
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Re: New belts for cassette tape mechanisms « Reply #18 on: October 05, 2020, 05:04:01 PM » Author: Fluorescent05
To make it clear, all plastics contain plasticizers. (Without them, they would become something that looks similar to UV-damaged material that crumbles to dust). The problem is with some types of plasticizers used in cheap bands, which may not stay in place but could diffuse from the band to the pulley through the contact surface between them

So do any belts have none of those types of plasticizers, and if so, where can I find them?
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Re: New belts for cassette tape mechanisms « Reply #19 on: October 05, 2020, 06:34:13 PM » Author: Ash
I have no definite answer to identifying the good vs bad at the retailer level. I expect that any retailer that specialises in electonic/electromechanical bits would be ok. But there always could be the one who would sell black office rubber bands as if they were belts, along with the fake capacitors...
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Fluorescent05
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Re: New belts for cassette tape mechanisms « Reply #20 on: October 05, 2020, 06:37:32 PM » Author: Fluorescent05
I have no definite answer to identifying the good vs bad at the retailer level. I expect that any retailer that specialises in electonic/electromechanical bits would be ok. But there always could be the one who would sell black office rubber bands as if they were belts, along with the fake capacitors...
Fake capacitors? What are they?
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Medved
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Re: New belts for cassette tape mechanisms « Reply #21 on: October 05, 2020, 11:58:12 PM » Author: Medved
Fake capacitors? What are they?

Standard electrolytic put into a cease of e.g. higher current or temperature rated. Mainly with the larger types.
It is not that rare type of electronic component frauds happening in the component business.
Fortunately even Chinese government is going after these fraudsters for quite some years now, but the problem havent completely disapeared.
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joseph_125
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Re: New belts for cassette tape mechanisms « Reply #22 on: October 06, 2020, 02:09:49 AM » Author: joseph_125
I think the PRB brand belts are also of decent quality.

A word of warning on using too cheap belts though, some of them will significantly increase the wow and flutter of your cassette mechanism, in that I mean to a level that would be audible especially in passages with sustained notes or piano music.
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Fluorescent05
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Re: New belts for cassette tape mechanisms « Reply #23 on: October 06, 2020, 07:28:57 AM » Author: Fluorescent05
I think the PRB brand belts are also of decent quality.

A word of warning on using too cheap belts though, some of them will significantly increase the wow and flutter of your cassette mechanism, in that I mean to a level that would be audible especially in passages with sustained notes or piano music.
Is that caused by thinner and thicker belt spots? Where do you find PRB belts?
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joseph_125
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Re: New belts for cassette tape mechanisms « Reply #24 on: October 06, 2020, 04:12:21 PM » Author: joseph_125
I believe there are a few sellers online. Vintage Electroncics and A1 Parts list them.

Yeah uneven thickness, improper belt size, and sometimes even too thick of a belt can cause excess W&F. Granted the problem is seen more in the more complicated mechanisms like the ones that use dual capstans. 
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Fluorescent05
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Re: New belts for cassette tape mechanisms « Reply #25 on: October 06, 2020, 04:22:22 PM » Author: Fluorescent05
I believe there are a few sellers online. Vintage Electroncics and A1 Parts list them.

Yeah uneven thickness, improper belt size, and sometimes even too thick of a belt can cause excess W&F. Granted the problem is seen more in the more complicated mechanisms like the ones that use dual capstans. 
Sorry for the dumb question but what is a capstan? Are they the thin shafts (usually attached to a large wheel behind) that the pinch rollers press up against?
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Re: New belts for cassette tape mechanisms « Reply #26 on: October 06, 2020, 04:29:34 PM » Author: joseph_125
Yeah the thin shafts with a flywheel attached to them that the pinch rollers press against are the capstans. Auto reverse mechanisms also have dual capstans but only one side is ever engaged when playing, the second capstan on those would be for the reverse direction.

The dual capstan mechanisms I've mentioned are unidirectional and keep both capstans engaged while playing.
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Fluorescent05
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Re: New belts for cassette tape mechanisms « Reply #27 on: October 06, 2020, 05:54:28 PM » Author: Fluorescent05
Yeah the thin shafts with a flywheel attached to them that the pinch rollers press against are the capstans. Auto reverse mechanisms also have dual capstans but only one side is ever engaged when playing, the second capstan on those would be for the reverse direction.

The dual capstan mechanisms I've mentioned are unidirectional and keep both capstans engaged while playing.
My mechanism is an auto reverse that has 2 capstans and a large (3.25 inch diameter) belt. Is the longer belt the reason cheap Chinese belts might have wow and flutter problems? In that case, would I be better off just boiling the belt because it only slips a bit on the reverse side where it doesn't make as much contact with the capstan?
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Re: New belts for cassette tape mechanisms « Reply #28 on: October 06, 2020, 10:15:32 PM » Author: joseph_125
The cheap Chinese belts are definitely hit or miss IMO. The pack I got seemed to cause excessive wow and flutter in every deck or walkman I've put them in. I've stopped using them for capstans and only use them as reel and counter belts now.

I never tried boiling a belt but I heard you could tighten them up that way, but did you try cleaning the belt and pulleys with isopropyl and seeing if that improves the grip?

I guess whether you buy a cheap belt or a more expensive belt depends on how much you plan to listen to it and if you plan to do any recording. I would opt for the more expensive belt if you plan to listen to it often as audible wow and flutter is kind of annoying IMO. 
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Fluorescent05
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Re: New belts for cassette tape mechanisms « Reply #29 on: October 06, 2020, 10:54:07 PM » Author: Fluorescent05
The cheap Chinese belts are definitely hit or miss IMO. The pack I got seemed to cause excessive wow and flutter in every deck or walkman I've put them in. I've stopped using them for capstans and only use them as reel and counter belts now.

I never tried boiling a belt but I heard you could tighten them up that way, but did you try cleaning the belt and pulleys with isopropyl and seeing if that improves the grip?

I guess whether you buy a cheap belt or a more expensive belt depends on how much you plan to listen to it and if you plan to do any recording. I would opt for the more expensive belt if you plan to listen to it often as audible wow and flutter is kind of annoying IMO. 
I have cleaned the belt slots on both capstans and the motor's belt slot with 70% isopropyl  alcohol. I also cleaned the belt with the same 70% isopropyl alcohol. Before cleaning, forward play and fast forward were normal speed and there was enough force to automatically reverse, however, reverse play and rewind were slowed down and it slipped too much to either reverse back to forward play (if the "reverse mode" button is out) or reverse back and pop the play button (if the reverse mode button is in). Now, the forward play and fast forward still work fine. The reverse play now plays at the proper speed, but it still slips too much to reverse back to forward.
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