Hello everyone,
I'm new here in a way but have been a member for a while now and, yes, I do give financial support so I'm not just a drive-by. Up front I'll say that I'm a fellow traveler as an "audio guy", not cutting now, though I have at times.
Specifically I run Fairchild 750 tables for playback and am trying to develop a source for belts, which they share in common with the 740 lathe. I've been doing a bit of work on this but thought I'd ask if anyone here has already gone down this path. If so I'd love to know what has been found as a source and even if no one has that's a help too. I'll certainly share what I end up with. Nothing being sold as a 750 or 740 belt that I've seen is anywhere near correct. I'm working out the details to have some fabricated but I'd be much happier if one of you has a solution already.
Thanks!
Topper
Fairchild 740 Belts
Moderators: piaptk, tragwag, Steve E., Aussie0zborn
Re: Fairchild 740 Belts
Oh that it was that simple. I wasted my money buying two of these a while back and they were way too thin and way too narrow and immediately ran afoul of the speed change. It was pretty obvious that they had never come close to the real thing. If you actually have a 740 and more recent experience with these I'd love to know that but I'm sceptical. I do appreciate the suggestion, though.
W
W
Re: Fairchild 740 Belts
They look pretty darned thick. I use belts for my lathe platters, but they're only 3.0 mils thick. so my OEM may not be helpful if you need them thick. The thickness (aka 'ply') is definitely part of the gear-ratio of the platter and motor pulley system. I could not use a 3.5 mils thick belt, for example. Has to be 3 point o.
Of course, I would still love to 'belt' you. (;
There's a different belt vendor also in shady Las Vegas who cites 750 replacement belts, here:
http://www.elexatelier.com/fairchild.htm
There are 740 belts (supposedly) sold here:
http://turntablebasics.com/belts/fairchild.html
...and a round belt (supposedly) for the 750, here:
https://www.turntableneedles.com/fairchild-model-750-round-drive-belt-rbs4.6-fairchild-750
A 750 player, without tonearm. was being sold on ebay, and the auction ended just yesterday. The description reads that it comes with 'several extra belts'.
https://i.ebayimg.com/images/g/ghMAAOSw91FhgCnF/s-l1600.jpg
It's the same vendor (going by "peace.love.and.music") who's selling a Fairchild 642 cutting head (5k USD!).
Reaching out to this vendor and/or posting a similar enquiry on the Vinyl Engine may yield better results.
Bonne chance!
Of course, I would still love to 'belt' you. (;
There's a different belt vendor also in shady Las Vegas who cites 750 replacement belts, here:
http://www.elexatelier.com/fairchild.htm
There are 740 belts (supposedly) sold here:
http://turntablebasics.com/belts/fairchild.html
...and a round belt (supposedly) for the 750, here:
https://www.turntableneedles.com/fairchild-model-750-round-drive-belt-rbs4.6-fairchild-750
A 750 player, without tonearm. was being sold on ebay, and the auction ended just yesterday. The description reads that it comes with 'several extra belts'.
https://i.ebayimg.com/images/g/ghMAAOSw91FhgCnF/s-l1600.jpg
It's the same vendor (going by "peace.love.and.music") who's selling a Fairchild 642 cutting head (5k USD!).
Reaching out to this vendor and/or posting a similar enquiry on the Vinyl Engine may yield better results.
Bonne chance!
Re: Fairchild 740 Belts
I reached out to the Fairchild on ebay guy about buying one of the belts and he told me no. 
I am also looking for a 750 belt. The 750-2 definitely has a flat belt, not a round belt.
I am also looking for a 750 belt. The 750-2 definitely has a flat belt, not a round belt.
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Re: Fairchild 740 Belts
For the general interest and to document this here...
The picture of the LP tunes belt looks fine but it's generic and not at all what the supply. And LP tunes is the same operation as Alexatelier so that is a dead end as well.
The Turntable Basics site lists a 35.1 belt for the 740 which isn't correct by (pardon the pun) any stretch. They also have a listing for the belt for a Fairchild 500, which is a tonearm not a table. Oops. (Another btw is that there are quite a few different thicknesses of 35.1 belts available across the web and most of them are incorrect for the smaller Fairchild tables, too.)
A round belt is just wrong, though if one were willing to do the math, locate the proper thickness, and forgo speed change replacing the pulley might allow that to be an option. I've considered it.
Lastly, finding an original replacement belt is appealing and I've found a few but I have a growing pile of snapped and about to snap ones sitting here. I just swapped out another yesterday, cracked almost through in two places. It's not the answer, sadly, as after 50 years or so they're too fragile in use even though they seem fine visually at first. I'm keeping on this.
The picture of the LP tunes belt looks fine but it's generic and not at all what the supply. And LP tunes is the same operation as Alexatelier so that is a dead end as well.
The Turntable Basics site lists a 35.1 belt for the 740 which isn't correct by (pardon the pun) any stretch. They also have a listing for the belt for a Fairchild 500, which is a tonearm not a table. Oops. (Another btw is that there are quite a few different thicknesses of 35.1 belts available across the web and most of them are incorrect for the smaller Fairchild tables, too.)
A round belt is just wrong, though if one were willing to do the math, locate the proper thickness, and forgo speed change replacing the pulley might allow that to be an option. I've considered it.
Lastly, finding an original replacement belt is appealing and I've found a few but I have a growing pile of snapped and about to snap ones sitting here. I just swapped out another yesterday, cracked almost through in two places. It's not the answer, sadly, as after 50 years or so they're too fragile in use even though they seem fine visually at first. I'm keeping on this.
Re: Fairchild 740 Belts
As you may know already, the circumference of a belt doesn't affect the speed - but it will affect the removal and replacement ability, given whatever positioning constraints are applied by the motor mount and/or for æsthetics, if the position of the works is at all visible.
I'm almost gladdened to read about someone else having difficulty sourcing a compatible belt for a gramophone machine, since I had a hell of a time getting the right belt, even after I contacted the OEM. He was already semi-retired and had stored his belt-making jig away, which took a while for him to set back up. Also, he didn't have the exact specs, anymore, since he hadn't made them for the manufacturer since 1979, and I was calling him in 2013 or so. Plus which, since the belts I use are made from a calendar which is ultrasonically welded to the target circumference and is then slit, just like analog tape, into individual belts, I had to buy multiple belts at once, since no other customer would likely require these specs. Each time, we had to experiment with the ply and also, to some degree, the material, which ended up having to be Mylar and not Kapton, even though they're very similar and normally Kapton is a good replacement material for Mylar belts (where speed is either adjustable or at least more tolerant). But its coefficient of friction was not the same and caused the strobe pattern to drift and make audible flutter. Once we narrowed down the ply to 3.0 mils, I still had to order a subsequent batch because the last one's belts had a bit too much length, so the motor cover was not close to the edge of the platter, where it normally should be. It cost so many thousands of rupees, just to get a new set of belts (which are a lifetime supply for the lathes) that it was as if I had become a lathe manufacturer, rather than just an owner-operator.
So, though unhelpful, it actually sounds as if the ebay vendor is making the right choice in not selling spare belts. His Fairchild 750 has no tonearm, and, without these unobtainable belts, his machine would be a boat anchor. Without the right stylus model, a cutting head is a fancy paper weight. Similarly, without the correct belt, or at least one with the necessary attributes, a record (non-)player is merely a curio.
Hopefully you will find NOS belts, but you might have to use one of your old and breaking ones as a modelo to have someone 3-D print a replica (; , or something even more elaborate, such as get into belt manufacturing, as I had to do for mine, in order for your machine to be usable well into the future.
- B. V.
I'm almost gladdened to read about someone else having difficulty sourcing a compatible belt for a gramophone machine, since I had a hell of a time getting the right belt, even after I contacted the OEM. He was already semi-retired and had stored his belt-making jig away, which took a while for him to set back up. Also, he didn't have the exact specs, anymore, since he hadn't made them for the manufacturer since 1979, and I was calling him in 2013 or so. Plus which, since the belts I use are made from a calendar which is ultrasonically welded to the target circumference and is then slit, just like analog tape, into individual belts, I had to buy multiple belts at once, since no other customer would likely require these specs. Each time, we had to experiment with the ply and also, to some degree, the material, which ended up having to be Mylar and not Kapton, even though they're very similar and normally Kapton is a good replacement material for Mylar belts (where speed is either adjustable or at least more tolerant). But its coefficient of friction was not the same and caused the strobe pattern to drift and make audible flutter. Once we narrowed down the ply to 3.0 mils, I still had to order a subsequent batch because the last one's belts had a bit too much length, so the motor cover was not close to the edge of the platter, where it normally should be. It cost so many thousands of rupees, just to get a new set of belts (which are a lifetime supply for the lathes) that it was as if I had become a lathe manufacturer, rather than just an owner-operator.
So, though unhelpful, it actually sounds as if the ebay vendor is making the right choice in not selling spare belts. His Fairchild 750 has no tonearm, and, without these unobtainable belts, his machine would be a boat anchor. Without the right stylus model, a cutting head is a fancy paper weight. Similarly, without the correct belt, or at least one with the necessary attributes, a record (non-)player is merely a curio.
Hopefully you will find NOS belts, but you might have to use one of your old and breaking ones as a modelo to have someone 3-D print a replica (; , or something even more elaborate, such as get into belt manufacturing, as I had to do for mine, in order for your machine to be usable well into the future.
- B. V.
Re: Fairchild 740 Belts
I do understand the math and the interactions. It would be a lot simpler just to be oblivious but it's way too late for that. My mention of "stretch" there is that they're suggesting a belt that's almost a foot too short and the wrong everything else, too. The challenge is finding the correct thickness in pre-made belting for the 740/750 and so far I haven't. This week's step forward is probably asking how heavy a hit I take working them up from scratch. One of the reasons I was asking here was to see if there was any greater interest and demand. I'm still curious about how any cutters can be running a 740 lathe without a properly sized belt...
Re: Fairchild 740 Belts
Oblivious to...?
Have you tried contacting Hamilton Records, in Argentina? They show a 740... and boast having "3 unidades indepentes".
http://www.hamiltonrecords.com.ar/tecnica.html
Alternatively, could a miniature variable frequency drive inverter can be obtained that would allow you to adjust the rate of the alternation of the power current going to the 750 to the specific frequency it needs when using a given wrong belt. That way, in the future, you could use belts that are within a range of plies, as needed, by adjusting the output frequency of the mVFD.
Have you tried contacting Hamilton Records, in Argentina? They show a 740... and boast having "3 unidades indepentes".
http://www.hamiltonrecords.com.ar/tecnica.html
Alternatively, could a miniature variable frequency drive inverter can be obtained that would allow you to adjust the rate of the alternation of the power current going to the 750 to the specific frequency it needs when using a given wrong belt. That way, in the future, you could use belts that are within a range of plies, as needed, by adjusting the output frequency of the mVFD.
Re: Fairchild 740 Belts
By oblivious I mean to the relationship of thickness to speed and blissfully not realizing if I'm running slow or fast. I'm committed to working this out.
I haven't contacted Hamilton but will. Just about every search I've done for the 740 through the years includes them but I haven't asked about a belt source.
And, interestingly, one of today's projects has already been to dig out my last VFD project.. A few years back I worked out how to speed control a Fairchild 412 with a small Siemens drive but that involved hooking the 3 phase motor up directly. The next iteration of that was to replace the Ashland motor on a 750 with a 3 phase and build up a drive for that.. The concept is good though the Bodine I used is too noisy and I moved on without taming it. (If anyone thinks about going this route for either table be aware that it makes a HUGE difference to filter the output after the Siemens. There's a similar Hitachi that may be cleaner but I haven't set that one up yet.)
The drawback to using a VFD is that it doesn't provide a universally applicable solution.
The right belt is one answer, a VFD is the second and cutting a different pulley is a third, though that may just be pushing the headache along to a future where it becomes a different sourcing problem. I have cut replacement 750 pulleys before and a run of new ones sized to use a standard belting dimension could be engineered again, I suppose.
And thank you indeed for the input here!
I haven't contacted Hamilton but will. Just about every search I've done for the 740 through the years includes them but I haven't asked about a belt source.
And, interestingly, one of today's projects has already been to dig out my last VFD project.. A few years back I worked out how to speed control a Fairchild 412 with a small Siemens drive but that involved hooking the 3 phase motor up directly. The next iteration of that was to replace the Ashland motor on a 750 with a 3 phase and build up a drive for that.. The concept is good though the Bodine I used is too noisy and I moved on without taming it. (If anyone thinks about going this route for either table be aware that it makes a HUGE difference to filter the output after the Siemens. There's a similar Hitachi that may be cleaner but I haven't set that one up yet.)
The drawback to using a VFD is that it doesn't provide a universally applicable solution.
The right belt is one answer, a VFD is the second and cutting a different pulley is a third, though that may just be pushing the headache along to a future where it becomes a different sourcing problem. I have cut replacement 750 pulleys before and a run of new ones sized to use a standard belting dimension could be engineered again, I suppose.
And thank you indeed for the input here!