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General => Off-Topic => Topic started by: Fluorescent05 on October 04, 2020, 01:51:38 PM

Title: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 04, 2020, 01:51:38 PM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: Ash on October 04, 2020, 02:47:28 PM
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
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 04, 2020, 03:53:33 PM
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 (https://fixyouraudio.com/) 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.
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 04, 2020, 04:18:26 PM
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 (https://fixyouraudio.com/) 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?
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 04, 2020, 04:20:01 PM
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!
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 04, 2020, 04:24:24 PM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: Ash on October 04, 2020, 04:26:23 PM
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
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 04, 2020, 05:49:32 PM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 04, 2020, 11:30:13 PM
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?
Title: Re: New belts for cassette tape mechanisms
Post by: Lightingguy1994 on October 05, 2020, 12:30:16 AM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: tolivac on October 05, 2020, 01:38:32 AM
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!
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 05, 2020, 02:17:24 AM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 05, 2020, 07:33:01 AM
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!
Title: Re: New belts for cassette tape mechanisms
Post by: Medved on October 05, 2020, 10:07:35 AM
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).
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 05, 2020, 10:12:56 AM
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?
Title: Re: New belts for cassette tape mechanisms
Post by: Medved on October 05, 2020, 10:52:42 AM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 05, 2020, 11:14:19 AM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: Ash on October 05, 2020, 04:38:40 PM
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
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 05, 2020, 05:04:01 PM
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?
Title: Re: New belts for cassette tape mechanisms
Post by: Ash on October 05, 2020, 06:34:13 PM
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...
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 05, 2020, 06:37:32 PM
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?
Title: Re: New belts for cassette tape mechanisms
Post by: Medved on October 05, 2020, 11:58:12 PM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 06, 2020, 02:09:49 AM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 06, 2020, 07:28:57 AM
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?
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 06, 2020, 04:12:21 PM
I believe there are a few sellers online. Vintage Electroncics (http://www.vintage-electronics.net/prb.aspx) and A1 Parts (http://www.a1parts.com/belts/prb_rubber_belts.htm) 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. 
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 06, 2020, 04:22:22 PM
I believe there are a few sellers online. Vintage Electroncics (http://www.vintage-electronics.net/prb.aspx) and A1 Parts (http://www.a1parts.com/belts/prb_rubber_belts.htm) 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?
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 06, 2020, 04:29:34 PM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 06, 2020, 05:54:28 PM
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?
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 06, 2020, 10:15:32 PM
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. 
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 06, 2020, 10:54:07 PM
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.
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 06, 2020, 11:00:48 PM
Ahh, yeah then I think your only option is to try to see if boiling it will work or replacing the belt. You can try looking up the service manual for your boombox online to see if it has the belt size or try using the PRB cross reference (http://russellind.com/client/download/PRB_Belt_XRef.pdf) for it. If you measure the belt you might want to subtract around 10% from the overall length to account for stretching over the years.

BTW if you're interested, I posted a couple of pictures of my cassette decks on the off topic gallery.
Title: Re: New belts for cassette tape mechanisms
Post by: Medved on October 07, 2020, 02:24:04 AM
I believe there are a few sellers online. Vintage Electroncics (http://www.vintage-electronics.net/prb.aspx) and A1 Parts (http://www.a1parts.com/belts/prb_rubber_belts.htm) 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. 

Or often contaminated or hardened pinch rollers are another cause.
Title: Re: New belts for cassette tape mechanisms
Post by: Medved on October 07, 2020, 02:27:43 AM
The dual capstan mechanisms I've mentioned are unidirectional and keep both capstans engaged while playing.

They are both rotating, but actually only one of them (the one pulling the tape from the heads in the selected direction) is really engaged by pressing the tape to it by the corresponding pinch roller. The other is just spinning freely in the air.
Title: Re: New belts for cassette tape mechanisms
Post by: joseph_125 on October 07, 2020, 03:00:28 AM
They are both rotating, but actually only one of them (the one pulling the tape from the heads in the selected direction) is really engaged by pressing the tape to it by the corresponding pinch roller. The other is just spinning freely in the air.


No, that is only for the auto reverse decks, I have a unidirectional dual capstan deck and both are engaged simultaneously while playing. If you read my entire comment, I differentiate between the two different types of mechanisms with dual capstans.
Title: Re: New belts for cassette tape mechanisms
Post by: Fluorescent05 on October 07, 2020, 07:34:10 AM
Or often contaminated or hardened pinch rollers are another cause.
Thanks for reminding me to clean them when I take it apart to boil the belt! I also have to clean the capstans where they touch the pinch rollers because they and the pinch rollers have this weird grime on them.