Sunday, June 24, 2012

Rek O Kut Tips


....vintage studio equipment in a scene from "The courtship of Eddie's Father", starring Glenn Ford..

Not much information can be found in cyberspace about the original Rek-O-Kut company based in NYC. But the company was a highly regarded manufacturer of turntables, tonearms and cutting lathes during the golden age of Hi-Fi. A lot of these idler driven turntables found duty in radio stations due to their quick start up time, stable speed and simple yet well executed engineering. My 1961 Lafayette catalog lists several idler models starting with the entry level 2-speed 4 pole induction motor driven Rondine Jr. L-34 [33 and 45] and L-37 [33 and 78], 3 speed Rondine B12 with same 4 pole motor as the L-34/L37, Rondine Deluxe B12GH which uses the Papst "flywheel" hysteresis motor and the the top of the line B12H which uses the HUGE hysteresis motor [see picture below]. By 1963 the L-34/37 Rondine Jr. series was replaced by the N33/34H belt drive which usually was fitted with the Papst motor. I have no experience with these models or motor but they have a good following.

All the Rek-O-Kut turntables are a model of engineering simplicity [no pitch control or eddy current brake] making the Garrard 301/401 and Thorens TD124 look over engineered. The motor and idler wheel arm assembly are individually isolated through rubber grommet mounts to prevent extraneous vibration from reaching the platter. The control switch physically moves the isolated motor with stepped capstan to engage the idler wheel at a chosen speed. Surprisingly the budget Rondine Jr. model employs dual idler wheels, the compromise being a simpler idler wheel arm assembly that does not need to be moved up or down to engage the capstan. Building a massive plinth for this model is very easy since it only requires a rectangular cut out to accomodate the motor unit. Due to the simple design the condition of the idler wheel[s] and rubber isolators as well as the few lubrication points have to be addressed to insure optimum operation.






The spindle is approximately 5/8" in diameter and comparable to those found in a TD124 or 301/401. The platter is a precision lathe turned aluminum weighing about 5-6 lbs. depending on the vintage [earlier models were lighter].

Pull out the platter and then remove [3 screws] the bearing well from the motor board. The inner rim of the platter and spindle should be cleaned and the bearing well should be flushed with lighter fluid or denatured alcohol. There should be a small ball bearing inside the bearing well. Inspect the condition of the ball bearing and if it shows signs of corrosion, replace it with a 1/4" or 5/16" ball bearing available from a bicycle shop. A brand new shiny ball bearing insures a smooth and silent turning platter. I am not sure what the original diameter of the ball bearing was but find that a 1/4" seems to turn a bit quieter than the 5/16" and the platter rests quite low on the top chassis which looks just like in the original brochures.


The motor assembly can be removed from the top chassis by unscrewing the switch knob [1] and the 3/8" hex nut on the opposite side [2]. Now is the time to check the condition of the rubber mounts [1& 2 below and two more on the other side not visible] 4 of these are used to isolate the motor. If they are pliable and free from cracks just clean up all the grease and accumulated gunk. Replacement rubber grommet mounts are still available from Lord Corporation in Erie, PA although I have yet to encounter cracked or glazed rubber mounts.


After years of storage the top and bottom motor bearings' lubricant may have gummed up. Spray Electric Motor Cleaner and compressed air into the oiling turrets [marked with arrows]. Once the bearings are turning without significant resistance, light oil can be added. 



To clean the idler wheel bearing remove the E-clip and flush the stud [1], brass bearing [2] and washers with lighter fluid. For reassembly the sequence [from bottom to top] is - thick washer, thin washer, idler wheel, thin washer, thick washer then E-clip. I use thin gun oil to lubricate the stud and brass bearing.



Idler wheel condition is very critical for a quiet running ROK. Minute flat spot[s] in the idler wheel will definitely be heard as loud rumble. It has been suggested in the Vinyl Asylum that cleaning the rubber with lacquer thinner can rejuvenate a "not so tired" idler. With the platter off, turn on the motor and engage the idler while brushing the rubber wheel with a small paint brush dipped in lacquer thinner. Sometimes this trick will work but if the rubber hardens and becomes noisy when it dries up, it needs to be refurbished. It didn't work on this particular idler wheel set. 


Worn out idler wheel - the rubber is glazed and hardened, it also measures 1/32" less than 2.5"



Refurbished idler wheel is exactly 2.5" in diameter

The turntable is now almost as quiet as my Garrard 301. Mechanical noise should not be audible 4 feet away from any idler driven deck in a quiet room. Another way to determine a worn out or glazed idler wheel is to try grabbing the platter and if it stops easily or does not offer much resistance the rubber is slipping.


According to the manual SAE 20 motor oil is the recommended viscosity for the main bearing. I use non-detergent SAE 30 and you only need to pour in enough oil to cover the top of the ball bearing and then rubbing some to the spindle before inserting the platter into the bearing well. As pictured the tip of the 1/4" bearing I used is not quite submerged in oil and needs a couple more drops.


This picture shows the position of the set screws with rebuilt idlers installed and speed calibrated. Although there is no pitch control in most ROK models, speed can be fine tuned by moving the set screw along the arrow marked directions. The motor should have been running for at least 15 minutes before adjustments are made. In general it would be prudent to keep the idler to rim tension at a minimum [closer to the knob] to prevent premature idler wear. Too much tension with good idlers slow down the speed and generate more noise. Proper tension is obtained when the platter locks in to speed within a couple of minutes. I use a neon pilot lamp from Radio Shack soldered/heatshrink wrapped to a long AC cord to view the stroboscope markings.



Other Models


Rondine Jr. L-37 and LP743 - 3 speed

These are very similar in design but the earlier LP743 has rather innovative features - the same idler is used for 33 and 45 and the mechanical switch to the extreme right changes the height of the idler to match the 33 or 45 rpm capstans of the motor. The idler on the left is exclusively a driving wheel to spin [no contact with the motor capstan] the platter at 78 rpm. However the idler arm on the LP 473 is directly attached to the top plate so the idler is rigidly in contact with the inner rim on start up whereas the L-34/37's idler arm is mounted on a substructure isolated by 3 rubber grommets contributing to less mechanical noise but a tad less kick on start up.



The bottom idler wheel [marked with an arrow] is driven by the bottom capstan [78 rpm] in the motor shaft which then transfers the motion to the top idler wheel to turn the platter. This pair of idler wheels for 78 rpm are mounted using set screws instead of an E-clip. The platter on the LP743 is slightly smaller and a bit lighter but the main bearing dimension and quality are identical. Earlier versions of the Rondine Jr. L-34 or L-37 also used this square type motor.

Idler wheels are not interchangeable between the B12H, LP473 and L-34/37.


Rondine Deluxe B12H fitted with a ROK S220 Gyropoise tonearm. This is the top of the line 3 speed model using a single idler wheel. Notice the tool kit under the platter?


The tools are provided to fine tune the speed and idler tension - the Allen wrench is used to remove the big control knob and the hex wrench to loosen the hex nut to fine tune the speed. As you slide towards 2 there is greater tension. Apply the same adjustment procedure as noted in the Rondine Jr.


Top motor is the hysteresis unit found in top of the line ROK machines, the bottom motor is from an L-37.


B12H stock plinth


Rek-O-Kut Rondine deluxe B12H after restoration and idler wheel rebuild. Tonearms CW from left: Pickering 190, Argonne AR600 and Velvet Touch.

Rek O Kut L34 Rondine Jr. + SME 3012 + Excel ES801
DIY Plinth

For more information and discussion of Rek-O-Kut turntables visit the Vinyl Asylum Archives.

Idler Wheel rebuilders:


30 comments:

  1. Sorry, last comment was typed from wrong account. Which table do you prefer, the B12h, or the L34? I know the B12H comes with a better motor, but does the L34 sound as nice with the lesser motor?

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    1. Hi Jonas,
      It's been over 10 years ago when I worked on these turntables. I always sent out the idler wheels for resurfacing but did not investigate replacement of the motor mounts. Then, I found that the Ashland on the B12H vibrated more than the motor on the L34. So I relegated the use of the B12H for my dedicated mono hifi set up where I've been very satisfied with its performance since the torque matches well with my heavy tracking tonearm/cartridge combos.

      Hope this helps and happy listening!

      JE

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    2. Like the function of oil going up with a bolt-like groove on the platter axis, because of this, it is initially slow, and after 15 minutes it becomes 33/3 constant, is this normal?

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  2. Hi JE thanks for this terrific blog, I recently bought a b12h and have it running with a calrad gray clone arm that has an empire 108 cartridge that I mounted on the plinth that it came with. The plinth is only about 2" high so I added some legs with the plan of building a stacked ply or mdf base in the future, the motor gets very hot to the touch, I see looking at forums that this is fairly common, is this just from the coils or is this indicating a problem, I replaced the oiling tubes and added oil. If this heat is normal, how should I construct a base to dissipate the heat, any tips on this or direction I should go with this i.e. Cartridge would be appreciated, thanks John Dunstan

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    1. Hi John,

      The Ashland motor really tends to run hot even after it has been cleaned and re-lubricated. So it is best to build a plinth that gives the motor a lot of room for ventilation.

      I've used the B12H + Velvet Touch 9" viscous damped arm (same as your Calrad) exclusively for mono playback with the Denon DL102 or GE VRII and RPX. Not familiar with the Empire 108, but if it is low compliance like a Stanton 500 or an older Shure M3D/M7D, then you are in the right direction.

      Hope this helps and happy listening!

      JE

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    2. Hi JE, I've noticed that the stepped drive spindle on the motor only engages half way up the idler wheel, is there an adjustment for this ordinance I have to pry the drive spindle up the motor shaft? Thanks

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    3. I never encountered this problem and AFAIK, there is no vertical adjustment for the motor. Have you tried fine tuning the idler tension as described above? That might help a bit but I surmise worn out/cracked motor mounts may cause gross misalignment since the motor is suspended/isolated by them. Check the condition of the motor mounts and make sure they are fitted properly.

      JE

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    4. Thanks JE, I will take the motor out and check all the mounts, they feel pliable, do you know if the stepped pulley is removable from the motor shaft, I see you have a post on ultrflex cabinets also, I had bought some on Craigslist, I may have to get your input on these at some point

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    5. The pulley is fixed in all the ROKs I've handled.

      JE

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  3. Thanks, was concerned I might be killing the motor, I have a ge vr ii also that I will probably set up in the micropoise arm

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  4. Any suggestions for cleaning and oiling a motor that doesn't have the oiling spouts? Thanks!

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    1. The only ROK motor I've handled that has no oil spouts is the Papst in my B12GH -http://jelabs.blogspot.com/2016/06/rebuilding-hi-fi-room.html - I just dismantled and relubricated the motor. It was a pretty straightforward job and didn't have the time to document the process except for the pictures in the above link.

      Hope this helps!

      JE

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  5. ok my question is about the rek o kut tone arm. the model 120. the mono arm. i have mine on a Rondine Jr. L-34, with the original plinth, with the off white painted top board( its aged in a way that looks awesome). i traded a tube amp i built for it at my local musical instrument, record, hifi, vintage gear etc shoppe. i also kinda work there. i dont really get paid in money, but whatever i need for a tube build or a record etc. anyhow back to my question. the ROK Model 120 non-adjustable antiskate system is giving me fits. the other day i tried playing a record with a bad stylus on a GE RPX single-play with what i thought was a young diamond stylus. i tried to do the needle dropping process and the arm jumped outta my hand. so i experimented and put on a sh-t record and let it do its thing it swung about three quarters toward the label and back and forth till it settled around mid record. i tried to work this out so its doing what antiskate should do and pull backwardsonld but when its set up this way the antiquate is so extreme toward even the center of the record it'll drag back across grooves. i wanted your opinion, i doubt this is normal. when i bought the arm offa ebay(the table had a counter weight-less/headshell-less,fairchild arm), the seller listed it as parts. it was a complete arm, mount, headshell, arm rest/clip, and was wired. the headshell was kinda messed with. it had different but nice new gold-plated connection pins with new springs from i guess a pioneer setup, but worked perfectly after utilized. l when i got it it was like brand spankin new the finish was perfect, i was so happy. only problem is i dont know how to adjust/ rest the antiskate springs in the bearing barrel i imagine is where they'd be? any info or advise would help. thx Nick

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    1. Hi Nick,

      I'm quite confused by your query because I do not know of a ROK tonearm that came fitted with anti-skate. The later version had a dynamic balancer on its side.

      If indeed yours has an anti-skate device, then disable it. If you set your tracking force properly, the tonearm should not skate across the LP.

      Hope this helps!

      JE

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  6. See that the needle is centered between the two plates of the GE cartridge, I changed my needle and had to tweak it with tweezers so that there is space on each side, also you need to set the tracking force to the cartridge specs, the bearing assembly can be adjusted for minimal play and friction, not anti skate

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  7. Any information on the R-34 Rek-O-Kut?? Finding nothing..

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    1. Nothing here, but a google search yielded quite a few leads...

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    2. I've googled for days and nothing. Every person I've spoken to hasn't a clue.please share if you have a specific web site that talks about the R-34.

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    3. Personally, I have no experience with that model.

      But here's a sample post from audiokarma.org which I found through google -http://audiokarma.org/forums/index.php?threads/rek-o-kut-turntables-rok.146608/page-8 - consider registering at that forum and post your queries.

      Hope that helps!

      JE

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    4. I already did. Closed conversation. Like I said I've pretty much seen everything out there including this site. Spoken to people that have done turntable repairs since the 60's and they don't know anything. But thanks anyway. Lol I'll find that needle in the hay stack.

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  8. Hi, I recently picked up a nice Rondo Deluxe and was following your helpful guide to service it. When I disassembled the guest motor to clean and relube it, I must have snagged the one of the windings and now it will not turn. Any advice? I have a feeling I may be royally f’ed :)

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    1. I'm not exactly sure what motor you are referring to but the wiring schematic of any ROK model is quite straightforward. Unfortunately I don't have any of them, but a google search should yield one for your particular model.

      Ever since I got a smart phone, I always take pictures of any component I'm working on for reference.

      JE

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  9. Hello, I have a ROK Rondine Jr. L-34. I've cleaned & oiled the motor. The issue is that on initial startup it plays slow. It takes 3-4 minutes to warm up and then plays fine. Is this normal for this vintage of turntable? The motor is a "Universal Electric Co" similar to the one you have pictured above ( red label ).

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    1. I've had the same issue with the same motor I thoroughly blasted with Electric Motor Cleaner. In such case I just lived with the 3-5 min. warm up.

      I've seen pictures of this motor disassembled for thorough cleaning. But I never ventured that far.

      The biggest stumbling block is, how to pry out the phenolic pulley? What if it cracks?

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    2. I followed the same cleaning procedures and also didn't want to pull the motor completely apart. As you said I will just have to live with 3-4 minute warmup.
      Thanks

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  10. Hi! I have a Rondine B12. I cant engage the 45rpm speed or the 78, only the 33 works. When I raise the plate to check what might be the problem, seems that the motor doesn't engage to those speeds. Also seems to have a ground issue. What can I try to fix this?

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    1. Check your idler wheel. Properly installed, the "flat" portion of the idler wheel should be facing up (see picture #14 above) if it's installed like the idler wheel at the back of picture #3, it won't engage other speeds.

      If that doesn't solve your problem, the mechanism was dismantled and improperly reassembled. Unfortunately, that's more complicated to fix. Go to this link - https://www.vinylengine.com/library/rek-o-kut/rondine-deluxe-b-12h.shtml - download "parts list" which will yield a mechanical drawing a B12H. That shows how the B12/12GH/12H turntable(s) were assembled.

      Hope this helps!

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    2. Thanks! You are the best!

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  11. I am looking for a Rek O Kut Rondine Jr. L-34 Idler Wheel Replacement. Suggestions?

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    1. I can recommend two brand new idler wheels:

      1. The Karmadon unit which I discussed in my ROK Tips update -https://jelabs.blogspot.com/2018/04/rek-o-kut-revisited.html

      2. eBay seller "laherbau" also manufactures brand new ROK idler wheels

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