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301 thrift store find

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more stakes and holy water for the undead

Postby josephazannieri » 14 Feb 2009 22:24

Just a quicky, and I have a hard time doing that. The screws that hold the TT to the motor board are 1/4 inch, but the Garrard screws are an oddball thread. You can't just go to the hardware store and get a Tee-nut that's going to work. You have the option of getting an oval-head standard thread screw, either coarse, 1/4 x 20 or fine, 1/4 x 28, and using a threaded insert. If you want to use the Garrard screws, you will have to find the nonstandard thread Tee-nut, which I think is 1/4 x 26. You will have to be sure that the oval head screw that you buy is the right size for the hole in the top of the Garrard. Otherwise, you can just use the standard Garrard screws, and drill up into the base far enough so that the standard Garrard nut can be used. At times like this, I am not the biggest fan of British engineering.

You said that your speed was spot on. That's great. You're in far better shape than I was when I got mine, provided that your speed control is CENTERED when the speed is spot on. I was able to get my speed spot on when I started with mine, but I had to have the speed control nailed to do it. Wound up having to clean and lube the motor to get it to come up to proper speed.

Great result!

Joe Z.
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301

Postby Blue Angel » 15 Feb 2009 00:37

Hi Iain

I've followed the resurrection of your 301 and Joe Z's and that of J.D.'s invaluable advices with much pleasure. I am sure once your turntable is set up, you will have a great deal of musical pleasure from it.

I did once ID the original Garrard screws by size, tpi and type of thread and still have the information somewhere on my computer. I already know this type of screw is available in the USA from suppliers and will look up the info if you need it.

In the meantime, I once had a similar problem in finding suitable screws but I'm not sure of Joe Z's t-nut description. I solved my own problem with a perfectly acceptable metric alternative, which I could order off the shelf locally. The screws needed (in metric) are dome-headed, countersunk and slotted 6mm stainless steel screws. I ordered mine in 75mm length, with matching stainless nuts and washers for each nut underneath.

The problem with any other kind of screw is that non-countersunk screws will damage the paintwork in the countersunk recesses. If you decide on the metric alternative, ensure that the screwdriver slots in the screwheads don't go right through the head as such slots will have burrs and also damage the paintwork as the screws are tightened. Also, when mounting the chassis in a plinth, care should be taken not to overtighten the screws as the chassis aluminium is fairly soft and can easily be deformed or dented around the screw recesses.

blue
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Re: more stakes and holy water for the undead

Postby iain42 » 15 Feb 2009 19:52

josephazannieri wrote:Just a quicky, and I have a hard time doing that. The screws that hold the TT to the motor board are 1/4 inch, but the Garrard screws are an oddball thread. You can't just go to the hardware store and get a Tee-nut that's going to work. You have the option of getting an oval-head standard thread screw, either coarse, 1/4 x 20 or fine, 1/4 x 28, and using a threaded insert. If you want to use the Garrard screws, you will have to find the nonstandard thread Tee-nut, which I think is 1/4 x 26. You will have to be sure that the oval head screw that you buy is the right size for the hole in the top of the Garrard. Otherwise, you can just use the standard Garrard screws, and drill up into the base far enough so that the standard Garrard nut can be used. At times like this, I am not the biggest fan of British engineering.

You said that your speed was spot on. That's great. You're in far better shape than I was when I got mine, provided that your speed control is CENTERED when the speed is spot on. I was able to get my speed spot on when I started with mine, but I had to have the speed control nailed to do it. Wound up having to clean and lube the motor to get it to come up to proper speed.

Great result!

Joe Z.


I could not resist the urge. The cannibalistic urges prevailed. I scavenged my RC88/4 for its switch assembly. I like it better as it has the clear top. The new one is still on the way but that is all right.

My brother bought a vintage British car and he did alot of cursing getting it restored. Thank god their aren't too many parts for me to worry about. I'd like to use the original screw but if I can't I'll try to match the best I can. I'll try to find a 1/4 x 26 tee nut to see if that works.

I spoke to soon about the speed being spot on as that was with a cold start and the speed control was at the -. After it runs for 15 minutes it is abit fast 2.5 - 3 rpm too fast. If I use the Variac to dial down the power I can get it perfect. I hope this is acceptable. I can't believe it is too fast but I guess that is better than too slow.
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Re: 301

Postby iain42 » 15 Feb 2009 20:03

Blue Angel wrote:Hi Iain

I've followed the resurrection of your 301 and Joe Z's and that of J.D.'s invaluable advices with much pleasure. I am sure once your turntable is set up, you will have a great deal of musical pleasure from it.

I did once ID the original Garrard screws by size, tpi and type of thread and still have the information somewhere on my computer. I already know this type of screw is available in the USA from suppliers and will look up the info if you need it.

In the meantime, I once had a similar problem in finding suitable screws but I'm not sure of Joe Z's t-nut description. I solved my own problem with a perfectly acceptable metric alternative, which I could order off the shelf locally. The screws needed (in metric) are dome-headed, countersunk and slotted 6mm stainless steel screws. I ordered mine in 75mm length, with matching stainless nuts and washers for each nut underneath.

The problem with any other kind of screw is that non-countersunk screws will damage the paintwork in the countersunk recesses. If you decide on the metric alternative, ensure that the screwdriver slots in the screwheads don't go right through the head as such slots will have burrs and also damage the paintwork as the screws are tightened. Also, when mounting the chassis in a plinth, care should be taken not to overtighten the screws as the chassis aluminium is fairly soft and can easily be deformed or dented around the screw recesses.

blue


I really hope others find this thread useful because I understood most of it and I'm not the most technical person in the lot.

The by size, tpi and type of thread would be a great help or compatable would also work : ). I'd like to be able to start seriously on the plinth in March. I'd like to use the original bolts but I can always got to the hardware store and match the best I can. The worst case is I spend a couple dollars on bolts so no big deal. I'll be very careful with the TT chasis. I'll treat it like it is not mine lol..

Thanks
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Postby iain42 » 15 Feb 2009 20:51

Sorry for spamming with posts today. :oops:

The actual size templates are going to be a big help for positioning holes for tonearms two 9 inch and a 12. I am going to use the plinth the Garrard was mounted on to make the initial cut with a router and a pattern bearing bit. This should yield the proper cut out for the table to sit in. The plinth is going to be a little larger than some of the ones out there. I'm thinking 10-12 layers of birch ply or something with a nicer grain IF I can find it locally. I read where someone rotated each ply 90 degrees from the previous ply to help reduce/absorb vibration. This seems easy enough to try.


Does it really matter what glue is used? I saw some talking about hide glue.



I really wish there was a "standard" for tonearm holes or is there and I haven't noticed. I'd like to have all cuts made at once but this may not be feasable. I've found ground plates for the rega and sme which makes life easier. As far as 9 inch I'll use the Garrad TPA for 78s and I already have that mount hole in the original plinth so not trouble here. Initially going to start with Rega rb300 for affordability. What I'll save my pennies for is a 12 inch arm. Not totally sure what I will end up with for the 12 inch arm as that is down the road or if a deal comes up and I have the cash at the time. The SME 12 seems to be very hot and sells well. The Scheu Classic seems to be very affordable when it is on the used market and he seemed to really have a passion for audio. Perhaps I could have mounting plate made for whatever arm I get but that could be pricey. If what I describe sounds like a bad idea please let me know. I'd like to have a plinth with maximum flexibility so even if I pickup a different tonearm than planned it can work. I need to read more about tonearm setup and plinth prep as I am woefully ignorant on this subject.

For sme this certainly makes life easier.
Image

For rega. It looks like what i would need but not sure about the claims. I hate audiophile technobabble. It puts me into a trance. The proof is in the hearing and not how many high scoring scrabble words you can use to describe it : )
http://www.vtaf.com/index.html
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301 Thrift...

Postby Blue Angel » 15 Feb 2009 22:34

Hi

Those 301 screws are countersunk, dome-headed and slotted 1/4" BSF, 26 tpi. There are engineering supply firms in your country stocking them.

blue
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Speed too fast

Postby josephazannieri » 15 Feb 2009 23:25

Yo Iain:

Blue Angel got the same thread count as I did, which is 26 threads per inch. I just took one of my screws and a caliper, and counted the threads. This is not standard in U. S., but, as Blue Angel says, you may be able to find screws from some enginering outfit, or a merchant of oddball screws who handles such items. You will also see the Garrrard screws on Ebay sometimes. You have the option of just using a good quality 1/4" flathead or oval head screw, and going with your desired length and a standard thread. Depends on how exact you want to be.

You can check something that might be making your speed a little to fast, Check the position of the idler wheel on the pulley. If the idler wheel is rubbing the next higher pulley step, which would be 45 RPM when the speed is set at 33, it may be increasing the speed of the idler wheel enough to cause the high speed that you are complaining about. One other possibility is that you have a 50 Hz pulley. The 50 Hz is usually steel (gray), and the 60 Hz is usually brass (yellow). My guess is that the pulley is right, and I remember that it looked like brass. But, there are some BRASS 50 Hz pulleys available on Ebay, and you may have one, though it's not likely.

In addition, be sure that the magnets on the eddy brake are positioned properly. With the control centered, the magnet should extend about 1/4 to 5/16 over the edge of the eddy brake plate. You can't do without the eddy brake being a little on. It stabilizes the system.

Check your speed at 78 RPM with a strobe. There is no step above 78, so you won't have the step issue. If it's too fast at 78, then it's probably the motor, or the eddy brake is out of position.

Keep on turning!

Joe Z.
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Re: 301 Thrift...

Postby iain42 » 16 Feb 2009 01:56

Blue Angel wrote:Hi

Those 301 screws are countersunk, dome-headed and slotted 1/4" BSF, 26 tpi. There are engineering supply firms in your country stocking them.

blue


Thanks.
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Re: Speed too fast

Postby iain42 » 16 Feb 2009 02:08

josephazannieri wrote:Yo Iain:

Blue Angel got the same thread count as I did, which is 26 threads per inch. I just took one of my screws and a caliper, and counted the threads. This is not standard in U. S., but, as Blue Angel says, you may be able to find screws from some enginering outfit, or a merchant of oddball screws who handles such items. You will also see the Garrrard screws on Ebay sometimes. You have the option of just using a good quality 1/4" flathead or oval head screw, and going with your desired length and a standard thread. Depends on how exact you want to be.

You can check something that might be making your speed a little to fast, Check the position of the idler wheel on the pulley. If the idler wheel is rubbing the next higher pulley step, which would be 45 RPM when the speed is set at 33, it may be increasing the speed of the idler wheel enough to cause the high speed that you are complaining about. One other possibility is that you have a 50 Hz pulley. The 50 Hz is usually steel (gray), and the 60 Hz is usually brass (yellow). My guess is that the pulley is right, and I remember that it looked like brass. But, there are some BRASS 50 Hz pulleys available on Ebay, and you may have one, though it's not likely.

In addition, be sure that the magnets on the eddy brake are positioned properly. With the control centered, the magnet should extend about 1/4 to 5/16 over the edge of the eddy brake plate. You can't do without the eddy brake being a little on. It stabilizes the system.

Check your speed at 78 RPM with a strobe. There is no step above 78, so you won't have the step issue. If it's too fast at 78, then it's probably the motor, or the eddy brake is out of position.

Keep on turning!

Joe Z.


I'm going to try my best to find the proper tnuts or threaded inserts. If not I'll take one of the bolts to a couple stores until I get the right ones. I also emailed a brittish supplier.

The idler wheel appears to be hitting in the right spot but I'll keep an eye on it to make sure. I guess I should also check and make sure it is level.

I'll use the eddy brake in the central position. It stabilizes the system. Wow. You learn something new all the time. These unassuming turntables are cram packed with technology.

I'll print out a strobe disc at work tomorrow and measure 78.
Thanks again!
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Postby iain42 » 16 Feb 2009 17:31

Some great progress thanks to others who have been down this road already. I've been proven wrong again which is no surprise. It seems there is not one size fits all tonearm hole or length but rather each is very specific.

Image

If you look at the arc for the 12 inch arms they are very close. If I can at least pick a location to mount it I can leave the top uncut but pre-cut the under layers wide enough so it can mount to the top ply when I am ready. I know exactly where the Garard TPA needs to be and now I know exactly where the Rega needs to be. When I upgrade to 12inch arm the Rega will be removed so I won't need three arms which could get crowded. <edit>Too much trouble to add so many arms. Going to save my pennies and sell plasma until I have enough for a 12 inch arm.<edit>

I was blissfully unaware of turntable science now I'm playing catchup.
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Postby iain42 » 22 Feb 2009 23:19

Well I found an old strobe that come with the TT and it is just a tad too fast. If the idler wheel is slightly touching the pulley on the 45 spot what do I do to lower it just a tad?

I was going to set up the garrard on my main system to spin a couple records but couldn't work with the strange wire from the tonearm. One of the wires had something that had been soldered but it doesn't feel like it is wire. It was actually covering the center wire. I'm wondering if I should rewire the TPA. Where do I find the modern version of this strange wire? Or am I better off trying to get it to work for me.

Image Not bad macro photography.
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301

Postby Blue Angel » 23 Feb 2009 00:31

Earth braid?

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Re: 301

Postby iain42 » 23 Feb 2009 04:17

Blue Angel wrote:Earth braid?

blue


Earth braid interesting. It appears the braid should get soldered to the negative and the very thin wire to the positive. I'm going to try to solder it even though it looks hopeless. The braid is as delicate as the the other thin wire.

I pealed cut back some insulation to give me something to work with.
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wires from arm

Postby josephazannieri » 23 Feb 2009 04:22

Ok, Iain, here's what to do to figure out the wires. Blue Angel is right. My guess is also that the braid is the ground from the cartridge, but go back to the instructions a I gave you earlier on the "nonstandard" arm wiring. I instructed you to measure to the RCA plugs, but it now looks as if there are no RCA plugs. The braid wire is the wire that would attach to the outside shield of the RCA plug. The insulated wire is the wire that would attach to the center pin of the RCA plug. You may have to strip these back a little and unwind the shield braid from off the center conductor. You can use a needle to unwind the shield braid. Just use the braid instead of the outside of the RCA plug and the insulated wire instead of the center pin of the RCA plug, and go ahead and make the measurements. This will identify the wires as left and right.

Here is what to do to get it hooked up to play records. Buy a 5-lug terminal strip. You may be able to find one at Radio Shack. Fasten the terminal strip to the underside of the motor board, close to where the arm wires come through. Buy a 6- foot dual RCA plug stereo patch cable from Radio Shack. Doesn't have to be expensive, less than $5.00 will work fine. Now fasten the wires coming from the arm to the lugs on the terminal strip, one wire per lug. You will have a braid on one lug, and the corresponding wire on the next lug. Make sure that you have good mechanical connections to the lugs. Do not solder anything now.

Now take the cheap dual RCA wire and pick one end, and snip the RCA connectors off of it. Use a knife and strip back the outer insulation about 1 to 1 1/2 inches. You will expose the shield braid. Unwind the braid from the outside of the wire. Use a needle to unbraid it if necessary. The inner conductor will now be exposed. Strip the insulation on the inner conductor back about 3/8 of an inch, exposing the wire. You will now have a dual RCA plug wire with exposed shield and condictor on one end. Take each shield braid, and solder it to the lugs on the terminal strip that already have shield braid on them. One shield to each lug. Now take each center conductor and solder it to one of the lugs with the center conductor on it. The shields and center conductors should not switch. So, you should have continuous shield all the way through, and contimuous center conductor all the way through each wire all the way to the RCA plug at the end.

Plug the RCA plugs into the phono inputs. Play a record. If it hums, then you will need a ground wire. Here's what you do now. Run a piece of #18 stranded wire, also from Radio Shack, to the ground lug on the motor Fasten the other end of the wire to the 5th lug. Do not solder. Take about 6 feet of #18 stranded wire and attach it to the 5th lug. Strip the loose end, and crimp a red spade lug, also from Radio shack, to the loose end. Now you can solder to the ground lug, and to the terminal lug on the strip. If you don't want to solder to the ground lug, you can use a ring connector and hook to the underside of the screws that hold the turntable to the motor board. You will now have a proper turntable ground wire. Tie this to the chassis of your amp. This should get you operational.

When you solder, don't go crazy with heat, lest you short the center conductor to the shield. Just enough heat to get the solder to flow. Also, when you strip wires, particularly when you strip the wires out of the arm, be careful that you don't cut the center conductor.

What do you mean by a tad fast? Can you get the right speed with the eddy brake? If you can, just use the eddy brake to set the speed. You will see that there are little set screws that hold the motor pulley on the shaft. You can loosen these and move the pulley up and down enough to line it up with the idler. Hope this helps. Good luck from the old constructor. You are now becoming a younger constructor.

Joe Z.
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