Columbia AT take apart

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JerryVan
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Re: Columbia AT take apart

Post by JerryVan »

Does it slide along nicely, then come to a hard stop, or does it gradually get tighter until it stops? The first suggests a part or burr that's in the way, the second suggests a probable pot metal distortion issue.

ts_13
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Re: Columbia AT take apart

Post by ts_13 »

Great advice all the way around.

It slides freely and with ease all the way until the end where it catches very abruptly. It does not feel like a swollen grab (if that makes sense) it it abrupt like the half nut is catching on the inside of the tube. The half nut is disengaged from the feed screw. The reason I am taking it off, is that the carriage has swollen and will not smoothly track in the grove that is located in the bed plate. So I need to file that part down a bit, but I cannot get the darn thing out.

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phonogfp
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Re: Columbia AT take apart

Post by phonogfp »

When you try to slide the carriage off the feedscrew sleeve, the half-nut will catch at the end of the slot of the feedscrew sleeve. It's a simple technique to accomplish your disassembly.

1) When the lift lever is pushed down, it lifts the reproducer PLUS it pushes down the half-nut to disengage it from the feedscrew. But it won't push it down far enough to clear the slot of the feedscrew sleeve. Here's a picture of the half-nut on an AT:
AT1_LI.jpg
2) You'll need a thin-bladed screwdriver. If you don't have a thin-bladed screwdriver, don't mess with this until you do. I bought a good-quality set of screwdriver bits and handle at Wal-Mart for ten bucks. It has served me well for ten years.

You'll need to CAREFULLY insert the thin blade of the screwdriver between the half-nut and the bottom of the lift lever, right in the center:
AT2.JPG
3) Now CAREFULLY angle the blade of the screwdriver so the half-nut is depressed a bit further than the lift lever can depress it. The half-nut can now clear the end of the sleeve.
AT3.JPG
Just be careful and you should be fine. Good luck!

George P.

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Curt A
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Re: Columbia AT take apart

Post by Curt A »

Thanks George, for that useful information for future projects... It definitely makes sense...
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"No one needs a Victrola XX, a Perfected Graphophone Type G, or whatever you call those noisy things."
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fran604g
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Re: Columbia AT take apart

Post by fran604g »

phonogfp wrote:When you try to slide the carriage off the feedscrew sleeve, the half-nut will catch at the end of the slot of the feedscrew sleeve. It's a simple technique to accomplish your disassembly.

1) When the lift lever is pushed down, it lifts the reproducer PLUS it pushes down the half-nut to disengage it from the feedscrew. But it won't push it down far enough to clear the slot of the feedscrew sleeve. Here's a picture of the half-nut on an AT:
AT1_LI.jpg
2) You'll need a thin-bladed screwdriver. If you don't have a thin-bladed screwdriver, don't mess with this until you do. I bought a good-quality set of screwdriver bits and handle at Wal-Mart for ten bucks. It has served me well for ten years.

You'll need to CAREFULLY insert the thin blade of the screwdriver between the half-nut and the bottom of the lift lever, right in the center:
AT2.JPG
3) Now CAREFULLY angle the blade of the screwdriver so the half-nut is depressed a bit further than the lift lever can depress it. The half-nut can now clear the end of the sleeve.
AT3.JPG
Just be careful and you should be fine. Good luck!

George P.
Excellent advice (as always) George!

Best,
Fran
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phonogfp
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Re: Columbia AT take apart

Post by phonogfp »

Curt A wrote:Thanks George, for that useful information for future projects... It definitely makes sense...
fran604g wrote: Excellent advice (as always) George!

Best,
Fran
There must be some positive outcome for all the mistakes I've made over the years...

George P.

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Curt A
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Re: Columbia AT take apart

Post by Curt A »

Mistakes are part of the learning process... learning 100s of things that don't work...
"The phonograph† is not of any commercial value."
Thomas Alva Edison - Comment to his assistant, Samuel Insull.

"No one needs a Victrola XX, a Perfected Graphophone Type G, or whatever you call those noisy things."
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ts_13
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Re: Columbia AT take apart

Post by ts_13 »

Outstanding! I believe that is exactly what the problem is. I will try to tackle it in a minute and post a follow up!

Update: Touchdown! That is exactly what was holding it. It is now apart, thank you.

T

phonogfp wrote:When you try to slide the carriage off the feedscrew sleeve, the half-nut will catch at the end of the slot of the feedscrew sleeve. It's a simple technique to accomplish your disassembly.

1) When the lift lever is pushed down, it lifts the reproducer PLUS it pushes down the half-nut to disengage it from the feedscrew. But it won't push it down far enough to clear the slot of the feedscrew sleeve. Here's a picture of the half-nut on an AT:
AT1_LI.jpg
2) You'll need a thin-bladed screwdriver. If you don't have a thin-bladed screwdriver, don't mess with this until you do. I bought a good-quality set of screwdriver bits and handle at Wal-Mart for ten bucks. It has served me well for ten years.

You'll need to CAREFULLY insert the thin blade of the screwdriver between the half-nut and the bottom of the lift lever, right in the center:
AT2.JPG
3) Now CAREFULLY angle the blade of the screwdriver so the half-nut is depressed a bit further than the lift lever can depress it. The half-nut can now clear the end of the sleeve.
AT3.JPG
Just be careful and you should be fine. Good luck!

George P.

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phonogfp
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Re: Columbia AT take apart

Post by phonogfp »

Glad it worked for you. Good luck with the rest of your restoration!

George P.

ts_13
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Re: Columbia AT take apart

Post by ts_13 »

Thank you!

phonogfp wrote:Glad it worked for you. Good luck with the rest of your restoration!

George P.
:arrow: :arrow:

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