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Audio-Technica Sound Burger (AT727) battery cover 3D model

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Audio-Technica Sound Burger (AT727) battery cover 3D model

Postby AudioVile » 18 Dec 2017 15:22

Hi!

I have a soundburger without a battery cover. I have recently gained access to a 3D printer.

Does anyone have a ready made 3D model file for a battery cover? That would save some trouble taking the measurements and making the model myself :D

Also, the motor makes a noticeable sound when powered on (it will be overdrowned by loud music but not by quiet passages). Is it supposed to make this noticeable motor sound? I'd presume this one has never been refurbished by anyone (save I've changed the broken needle)!

Thanks!

p.s. Just to make clear, the sound is coming externally from the unit/motor itself. The signal coming from the audio outputs is clear without (any obvious) interference!
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby AudioVile » 25 Feb 2018 17:29

It just happens that someone posted this on tingiverse, with sample pictures suspiciously looking exactly like they were taken from my unit! :D
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby Coffee Phil » 26 Feb 2018 04:40

Hi AudioVile,

If that file doesn't work out for you, I have an AT 770 which is the same machine with in my view a bit less silly name: Mister Disc. We have to find someone who can do a sutiable scan, then send you the file.

The motor in my Mister Disc does not make noise which is noticable to me. You might open the unit to see if the capstan is rubbing on anything. Also the motor is mounted to a plate which in turn is mounted to the case via grommets which are refered to as dampers in the parts list. You might check the condition of the "dampers".

https://www.vinylengine.com/library/audio-technica/at-727-sound-burger.shtml

Phil

AudioVile wrote:Hi!

I have a soundburger without a battery cover. I have recently gained access to a 3D printer.

Does anyone have a ready made 3D model file for a battery cover? That would save some trouble taking the measurements and making the model myself :D

Also, the motor makes a noticeable sound when powered on (it will be overdrowned by loud music but not by quiet passages). Is it supposed to make this noticeable motor sound? I'd presume this one has never been refurbished by anyone (save I've changed the broken needle)!

Thanks!

p.s. Just to make clear, the sound is coming externally from the unit/motor itself. The signal coming from the audio outputs is clear without (any obvious) interference!
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby AudioVile » 26 Feb 2018 18:07

Coffee Phil wrote:If that file doesn't work out for you, I have an AT 770 which is the same machine with in my view a bit less silly name: Mister Disc. We have to find someone who can do a sutiable scan, then send you the file.

I was being a bit silly / trying to be funny, but I know the person who uploaded the model to thingiverse, and the pictures actually are from my unit :wink:

It does work just fine. There's room for some improvement (also depending on the printer and type of plastic used): the sloped part tends to droop. That's why supports are needed for the model and / or tinkering with the settings of the 3D printer in use. I think the person printed the cover for me put some comments in the file (I never actually opened the file posted, but he said he would). He took this as just a nice project to test his printer!

Coffee Phil wrote:The motor in my Mister Disc does not make noise which is noticable to me. You might open the unit to see if the capstan is rubbing on anything. Also the motor is mounted to a plate which in turn is mounted to the case via grommets which are refered to as dampers in the parts list. You might check the condition of the "dampers".

https://www.vinylengine.com/library/audio-technica/at-727-sound-burger.shtml

Thanks, I suspected there's something wrong and I will open it up (when I have the time; this is not my primary turntable, just a nice collectible to own!). I was just wondering since I've checked with a strobodisc (or whatever you call that thing with the pattern for 50 and 60Hz), and I presumed if there was something wrong the rotation speed would be off, which it isn't. I suppose the dampers could cause this or something brushing against something that shouldn't, or perhaps dried out grease in the axle (?); in any case it isn't impeding rotation much, or the unit can compensate for it (since speed is OK).

It also has another issue: the aplification circuit takes some time to "warm up"; it takes 90+ seconds for both channels to give output (the other one is totally silent in the beginning, forgot which one). After this it seems quite OK to my ears, however! I suspect some electrolytic capacitors have dried out or something.

EDIT: Some typos and clarification of my thoughts

EDIT: It is also worth to mention, that the model was made by measuring the battery compartment hole. We had no original part to measure. The result is quite functional, however! At least the batteries are not falling out :D
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby Coffee Phil » 27 Feb 2018 18:30

Hi AudioVile,

I dragged mine out and turned it on. Even with my ear next to the case I can't hear the motor. I am of course pretty old. Maybe tonight I'll put a record on it and have a listen. It has never failed to impress me. I have misplaced to power supply which is bugging me, but it ran fine with the old C cells which were in it. I have to take those out and store them in a baggie. If they were to leak inside the player I'd be very upset.

If I remember the platter bearing is inverted so oil will leak out. I used white lithium grease. You may be able to drop some sewing machine oil into the top motor bearing, but the bottom bearing will be a challenge.

Compare the rise of voltage at the nodes in the bad channel to those in the good channel to aid in figuring out what is going on in the electronics. Also try the line out into your stereo to isolate the issue to the phono stage or the headphone amp.

Phil

AudioVile wrote:
Coffee Phil wrote:If that file doesn't work out for you, I have an AT 770 which is the same machine with in my view a bit less silly name: Mister Disc. We have to find someone who can do a sutiable scan, then send you the file.

I was being a bit silly / trying to be funny, but I know the person who uploaded the model to thingiverse, and the pictures actually are from my unit :wink:

It does work just fine. There's room for some improvement (also depending on the printer and type of plastic used): the sloped part tends to droop. That's why supports are needed for the model and / or tinkering with the settings of the 3D printer in use. I think the person printed the cover for me put some comments in the file (I never actually opened the file posted, but he said he would). He took this as just a nice project to test his printer!

Coffee Phil wrote:The motor in my Mister Disc does not make noise which is noticable to me. You might open the unit to see if the capstan is rubbing on anything. Also the motor is mounted to a plate which in turn is mounted to the case via grommets which are refered to as dampers in the parts list. You might check the condition of the "dampers".

https://www.vinylengine.com/library/audio-technica/at-727-sound-burger.shtml

Thanks, I suspected there's something wrong and I will open it up (when I have the time; this is not my primary turntable, just a nice collectible to own!). I was just wondering since I've checked with a strobodisc (or whatever you call that thing with the pattern for 50 and 60Hz), and I presumed if there was something wrong the rotation speed would be off, which it isn't. I suppose the dampers could cause this or something brushing against something that shouldn't, or perhaps dried out grease in the axle (?); in any case it isn't impeding rotation much, or the unit can compensate for it (since speed is OK).

It also has another issue: the aplification circuit takes some time to "warm up"; it takes 90+ seconds for both channels to give output (the other one is totally silent in the beginning, forgot which one). After this it seems quite OK to my ears, however! I suspect some electrolytic capacitors have dried out or something.

EDIT: Some typos and clarification of my thoughts

EDIT: It is also worth to mention, that the model was made by measuring the battery compartment hole. We had no original part to measure. The result is quite functional, however! At least the batteries are not falling out :D
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby dahoo » 27 Feb 2018 20:12

AudioVile wrote:It does work just fine. There's room for some improvement (also depending on the printer and type of plastic used): the sloped part tends to droop. That's why supports are needed for the model and / or tinkering with the settings of the 3D printer in use. I think the person printed the cover for me put some comments in the file (I never actually opened the file posted, but he said he would). He took this as just a nice project to test his printer!

Thanks for the pointer and I ordered one battery cover for one of my AT770 too.
It is in RED since i think the color won't match exactly anyway and why not use red for it to stand out and match the color of the stylus. Not sure of the setting you used for yours but more infill density as I researched will make the piece stronger.
Let me wait and see what mine will feel like.
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby dahoo » 03 Mar 2018 06:22

Red battery cover is here. It wasn't a perfect fit not because of the scan but the left side seems to have some rougher edges than the right, which is smooth plastic surface. I have to use knife to scratch the edges and make it fit.
Overall looks great.
IMG_3404.JPG
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby AudioVile » 13 Apr 2018 16:41

Nice that the 3D model has been put to use!

This is getting a bit OT now (I'm not talking about the cover anymore); sorry about that :wink:

I finally had the time to open up my unit, partially inspired by the fresh review by Techmoan. In that review he also compares it with the Killer rip-off by Crosley - recommended! 8)

In that review, he takes the unit apart. I ordered replacement belts from the link in the description, and changed them.

While doing that, I examined what is causing the noise. It is coming from the motor itself. The smaller (original) belt I have has becomed hardened/less stretchy and kind of loose (it is tear-shaped instead instead of round). The noise from the motor is alleviated with the fresh belt, since some sideways pressure on the motor axle will lessen the noise made by the motor, but it is not eliminated.

However, I'm having the same issue as Techmoan - both speeds are just a little bit too fast even with the adjustement screws at minimum. But with the original belts, I can adjust the speed to be 100% correct - although it will take some time for the speed to catch up, since the (smaller) belt is a bit too loose.

Any ideas - is this speed issue a common one? Have you tried / tested the exact speed of your unit(s) with a strobodisc?

Cheers!
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby Spinner45 » 13 Apr 2018 17:44

AudioVile wrote:While doing that, I examined what is causing the noise. It is coming from the motor itself. The smaller (original) belt I have has becomed hardened/less stretchy and kind of loose (it is tear-shaped instead instead of round). The noise from the motor is alleviated with the fresh belt, since some sideways pressure on the motor axle will lessen the noise made by the motor, but it is not eliminated.
Cheers!


Why ignore the obvious?
OIL the darn motor bearing!
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby Coffee Phil » 13 Apr 2018 18:03

Hi AudioVile,

I have set mine with a strobe disc. The speed stability is fairly good.

There are fixed resistors in series with the 5 K Ohm speed pots. R 401 is for 45RPM and is 20 K Ohms. R 404 is for 33 1/3 RPM and is 15 K Ohms. The manual is here: https://www.vinylengine.com/library/audio-technica/at-727-sound-burger.shtml

Greater resistance gives higher speed. I have even pushed mine up to 78.26 RPM although the motor control chip is running out of headroom. With a 5 Volt supply all is well. I have actually played 78 RPM micro groove records on it.

Phil


[ol ="AudioVile"]Nice that the 3D model has been put to use!

This is getting a bit OT now (I'm not talking about the cover anymore); sorry about that :wink:

I finally had the time to open up my unit, partially inspired by the fresh review by Techmoan. In that review he also compares it with the Killer rip-off by Crosley - recommended! 8)

In that review, he takes the unit apart. I ordered replacement belts from the link in the description, and changed them.

While doing that, I examined what is causing the noise. It is coming from the motor itself. The smaller (original) belt I have has becomed hardened/less stretchy and kind of loose (it is tear-shaped instead instead of round). The noise from the motor is alleviated with the fresh belt, since some sideways pressure on the motor axle will lessen the noise made by the motor, but it is not eliminated.

However, I'm having the same issue as Techmoan - both speeds are just a little bit too fast even with the adjustement screws at minimum. But with the original belts, I can adjust the speed to be 100% correct - although it will take some time for the speed to catch up, since the (smaller) belt is a bit too loose.

Any ideas - is this speed issue a common one? Have you tried / tested the exact speed of your unit(s) with a strobodisc?

Cheers![/quote]
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby dahoo » 14 Apr 2018 02:36

i remember when i replaced mine with new belts, it was a tight fit and the speed would go faster than normal. the adjustment pots were not enough.
i later had to reuse the old one by putting it in boiling water and cooling it down fast to acquire some elasticity.
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby Coffee Phil » 14 Apr 2018 04:35

As long as the belts are not so tight as to worry over excessive bearing loading another approach could be to measure the two resistors which I mentioned. If they are in tolerance, replace R 404 with 13 K Ohms and R 401 with 18 K Ohms. Put the removed parts in a zip-lock bag for possible future use.

Phil

dahoo wrote:i remember when i replaced mine with new belts, it was a tight fit and the speed would go faster than normal. the adjustment pots were not enough.
i later had to reuse the old one by putting it in boiling water and cooling it down fast to acquire some elasticity.
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby Keso77 » 14 Apr 2018 10:09

Hey!

Since we have some AT727/AT770 knowledge I thought I´d ask for some advice,

I got a Sound burger in a decent visual shape.

1AE85563-9B50-46AC-BF36-17CF6DF26771.jpeg
AT727 Sound burger


But It isn´t complete. Appart from the powersupply missing I will have to replace the belt, change the tonearm cables, grease it up and, toughest of it all, replace the missing cart.

0A67CA27-DB0B-4229-9322-F87B3C906302.jpeg
AT727 Sound burger tonearm


From what I gather I can use a stripped AT100 with a AT103 needle to get the work done but I am a bit puzzled when it comes to the headshell. Looks like there´s a screw and that it used to be glued. Anyone with any experience with replacing the cart with some pro tips?

DF8AD2E2-1C56-42B7-9518-DCE01858D349.jpeg
AT727 Sound burger HS
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby AudioVile » 14 Apr 2018 13:32

Spinner45 wrote:Why ignore the obvious?
OIL the darn motor bearing!

I will, as soon as I can gather some oil sufficient for this job :wink:

Coffee Phil wrote:There are fixed resistors in series with the 5 K Ohm speed pots. R 401 is for 45RPM and is 20 K Ohms. R 404 is for 33 1/3 RPM and is 15 K Ohms. The manual is here: https://www.vinylengine.com/library/audio-technica/at-727-sound-burger.shtml

Thanks, Phil (again).

It seems my unit has a 22k (Red-Red-Orange-Red) and a 15k (Brown-Green-Orange-Gold) resistors there. Any idea why they used 22k? The service manual indeed lists the part as 20k. Good thing I ahve a huge collection of resistors :-).
I think I will try some contact spray at the var resistors first (just in case they have oxidized) and see if it helps. If not, they'll get replaced.
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Re: Audio-Technica Sound Burger (AT727) battery cover 3D mod

Postby Coffee Phil » 14 Apr 2018 13:34

Hi Keso77,

It doesn’t look too bad. The belt are available on line. You can likely find them on eBay. Since speed is adjustable they aren’t too critical. I’m out of town now so I can’t measure the power supply plug, but it is common. Remember the center pin is negative. If you can’t find a 4.5 volt supply, 5 volts is OK and that is common as dirt.

The cartridge thing is where I didn’t want to go. If you figure how to get the cover for the cartridge screw off non destructively please share that info. The plastic 1/2 mounting bracket on many AT cartridges is retained with a screw and can be removed. There are AT experts here who can advise on which cartridge is the most compatible. I’m trying to play 78s on mine. This thread may have some useful cartridge info in it. https://www.vinylengine.com/turntable_forum/viewtopic.php?f=19&t=102775

The OEM cartridge is an AT 103 without the mounting bracket.

Removing the arm is not bad and is covered in the manual on this site.

Keep us posted on the progress.

Phil

Keso77 wrote:Hey!

Since we have some AT727/AT770 knowledge I thought I´d ask for some advice,

I got a Sound burger in a decent visual shape.

1AE85563-9B50-46AC-BF36-17CF6DF26771.jpeg


But It isn´t complete. Appart from the powersupply missing I will have to replace the belt, change the tonearm cables, grease it up and, toughest of it all, replace the missing cart.

0A67CA27-DB0B-4229-9322-F87B3C906302.jpeg


From what I gather I can use a stripped AT100 with a AT103 needle to get the work done but I am a bit puzzled when it comes to the headshell. Looks like there´s a screw and that it used to be glued. Anyone with any experience with replacing the cart with some pro tips?

DF8AD2E2-1C56-42B7-9518-DCE01858D349.jpeg
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