I see the point, it was worth asking. I thought it was one fast and one slower. Put a coin on the platter and count the rotations as it passes a pointer. Remember the first pass is zero. The reaction time on a stop watch is usually about the same stop and start, so error is low. See what you get. It might be you have a new pulley of a generic type has been fitted at some time to convert from 50 Hz to 60 Hz. It might be a general spec type. If like Garrard the pulley was from a range of sizes. The TD124 strobew window must be set for 50 or 60 Hz on the stobe. Be aware that the 45 is not exactly correct when on strobe. This below strobe is correct ( markings are elongated on 45 and 78 ). A stobe can be made using 2 x 74 HC4060 and 3.2768 MHz crytal. A 100 R series resistor to the red LED 10 mm hi-bright. A 7805 regulator and 9 V PP3 battery to power it.
All the pieces on the table are original, except for the upgrades I listed earlier. The pulley, strobe window, etc., are all original and in functioning order. I should say the bulb for the strobe was replaced by Schopper. I really do think that the 45rpm is just going too fast. Now is that a result of the power in my apartment, or something else. That is what we have to find out.
One thing worth checking is the ball beaing in the motor ( shaft end ). Be sure it is still there. 1000:1 outside chance. If you think about it the speed is just a gear ratio. It is either right or wrong. Get a vernier on the pulley and see if it is about 1.35 times bigger when 33 1/3 compared with 45. Maybe others could give vernier readings. When you say placing the stylus in the groove slows it should be below 0.1%. Long day, sorry if the English below parr.
All 124s from the factory are equipped with a dual frequency pulley that one flips over for 50 or 60Hz operation, and motors easily configurable for 100-125V, 125-150V and 200-250V mains.
Only the short lived derivative 121 version had a 60Hz specific pulley and single voltage windings and it was a North America only model.
). The ball bearing has to be in there, as it was rebuilt by Schopper and I doubt they left it out.
He was talking about vernier calipers, available cheaply at Harbor Freight, but I don't really see the point as this is an entirely stock table restored by Schopper which for all its quirks definitely knows the table well. As far as I can tell all the parts shown are original.
The problem you are having is encountered frequently here (60Hz land) by people with recently restored tables with modern lubricants and replacement belts. This is an issue I have had so far with about 9 tables I have worked on, usually the solution is to reduce the mains voltage which reduces motor torque enough to allow reasonable adjustments to be made.
Current replacement belts seem to be 20 - 50% thicker than the original and this has a huge impact on speed adjustment range as I have mentioned before. Buried somewhere in this thread (I think) are a bunch of measurements of a variety of different belts I have tried, the best results not surprisingly are generally with an original 50+ yr old belt.
I would try sticking a folded over post (one fold) it note between the magnet and the intermediate pulley in order to set the minimum gap possible.
Have you considered talking to Schopper about the speed problem you are having?
The problem you are having is encountered frequently here (60Hz land) by people with recently restored tables with modern lubricants and replacement belts. This is an issue I have had so far with about 9 tables I have worked on, usually the solution is to reduce the mains voltage which reduces motor torque enough to allow reasonable adjustments to be made.
Current replacement belts seem to be 20 - 50% thicker than the original and this has a huge impact on speed adjustment range as I have mentioned before. Buried somewhere in this thread (I think) are a bunch of measurements of a variety of different belts I have tried, the best results not surprisingly are generally with an original 50+ yr old belt.
I would try sticking a folded over post (one fold) it note between the magnet and the intermediate pulley in order to set the minimum gap possible.
Have you considered talking to Schopper about the speed problem you are having?
Hi Guys. Can anyone provide a circuit diagram or suggestions for a 220-230V power supply that i can use on my TD-124 (and CJ Walker 55)? I have a few issues with power in my area, and would like to try out a decent (but not too expensive) power supply. Nigel and KevinKr thanks for the advice on the oil - much appreciated.
Kevin, Pretoria RSA
Kevin, Pretoria RSA
an accurate crystal generated clock, into sinewave, into power amplifier, into transformer for a good fairly low impedance high voltage supply.
I bought a pair of crystal frequencies that had an exact 33.333 repeating : 45 ratio.
The intention was to generate two sinewaves to drive the synchronous motor at the required speed without having the the belt, or pulley.
I still have them in my parts bin.
Do you want the frequency numbers? They were standard parts available at sensible prices about 30years ago.
I bought a pair of crystal frequencies that had an exact 33.333 repeating : 45 ratio.
The intention was to generate two sinewaves to drive the synchronous motor at the required speed without having the the belt, or pulley.
I still have them in my parts bin.
Do you want the frequency numbers? They were standard parts available at sensible prices about 30years ago.
Precision Time Base For Microcontroller Circuits - CircuitStudy
50Hz 60Hz Frequency Generator Circuit Using Crystal Oscillator | Electronic Circuits
This is a start. The 74HC4060 being useful. 3.2768 MHz crystal ( 50 Hz ) and the old TV 4.43 Mhz is good enough for most people. The second link is slightly more complicated.
2 x 4060 can be linked into pin 11 on second to get extra counts. 12 is to 0V. If wondering the reset pin can be linked to an output to form a latch as one of it's many uses. This is a neat and cheap way to make a timer. Often a diode is used. The 0.7 V loss is inside the opperating range.
Next a filter is required. Somebody here might like to run with this.
http://www.ti.com/lit/an/slyt113/slyt113.pdf
50Hz 60Hz Frequency Generator Circuit Using Crystal Oscillator | Electronic Circuits
This is a start. The 74HC4060 being useful. 3.2768 MHz crystal ( 50 Hz ) and the old TV 4.43 Mhz is good enough for most people. The second link is slightly more complicated.
2 x 4060 can be linked into pin 11 on second to get extra counts. 12 is to 0V. If wondering the reset pin can be linked to an output to form a latch as one of it's many uses. This is a neat and cheap way to make a timer. Often a diode is used. The 0.7 V loss is inside the opperating range.
Next a filter is required. Somebody here might like to run with this.
http://www.ti.com/lit/an/slyt113/slyt113.pdf
I drew this some time ago. It should be about right. I would have used 74HC4060 and TL072 or 74. I have some PSU at 5V and +/- 12V which are ideal. Notice I have a 100 Hz output for a strobe 10 mm LED ( 100 R required in series as the highest output, The Ron of 4060 comes into it ). Notice how the higher current 74HC4060 will drive the first RC filter R1 C1. Black is 0V and red +5V. Vero strip board is OK for the build. Check I have the divide ports correct.
The -62 dB is the total effect at the 3 rd harmonic and the - 34 db is related to 100 Hz as sometimes it is important. These were notes to myself. The slight complexity is to avoid expensive components. The TL074 helps as it can work very well with very high value resistors ( none used here ). The gain of 2 was to suit a very simple power amp I had in mind. Sorry to say I lost the notes on that. I suspect it was an L165 in inverting mode and low gain. A very good amp for motors.
If you want to design filters without complex maths a series of simple passive filters and buffers can be used ( like R1 C1 ). The formula is Fo=1/2PixcC. 318K (300K+ 18 K ) and 10 nF would be usable for 50 Hz if TL074. At every second filter add 10K + 10 K gain, in between a unity buffer ( + to - input of op amp ). The filter will give about - 7dB 2nd harmonic and - 10 dB 3 rd. As the output of a squarewave is -9.5 db 3rd harmonic that implies 5 poles is a minimum ( circa - 60 dB total ). If you use a 50 Hz filter for 67.5 Hz add a gain switch to restore the output. Maybe if in the unity gain stages could be switch for gain . The 67.5 Hz will get slightly better filtering as a result as the -6 dB first order slope is becoming stonger. If you want build a 40 Hz filter and add gain for both. As 10 nF NPO are cheap an 8 pole filter is not too expensive and will work very well.
If you want to design filters without complex maths a series of simple passive filters and buffers can be used ( like R1 C1 ). The formula is Fo=1/2PixcC. 318K (300K+ 18 K ) and 10 nF would be usable for 50 Hz if TL074. At every second filter add 10K + 10 K gain, in between a unity buffer ( + to - input of op amp ). The filter will give about - 7dB 2nd harmonic and - 10 dB 3 rd. As the output of a squarewave is -9.5 db 3rd harmonic that implies 5 poles is a minimum ( circa - 60 dB total ). If you use a 50 Hz filter for 67.5 Hz add a gain switch to restore the output. Maybe if in the unity gain stages could be switch for gain . The 67.5 Hz will get slightly better filtering as a result as the -6 dB first order slope is becoming stonger. If you want build a 40 Hz filter and add gain for both. As 10 nF NPO are cheap an 8 pole filter is not too expensive and will work very well.
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What are the chances of platter having 50hz strobe markings instead of 60hz ? Or Is there any possibility that being an old part, eddy magnets is not strong enough ?
Regards.
All the cast iron platters have both set of strobes on them, so zero chance. As for the magnet not being strong enough, that is certainly a possibility. I just wish there was somewhere to buy a new or NOS one.
OK. I studied the mechanism from this website. EddyBrake
What looks like is that the speed control knob moves the steel flange (pic no. 3) in the link. So when you turn the star shaped speed control; does the steel flange move all the way ? So that the magnet gets fully exposed to the step pulley.
What looks like is that the speed control knob moves the steel flange (pic no. 3) in the link. So when you turn the star shaped speed control; does the steel flange move all the way ? So that the magnet gets fully exposed to the step pulley.
And this a very common issue with TD-124s, particularly the later MKII here in North America. They run fast and are tricky to adjust so that when warm they run at the right speed.
I have two and the MKII has this problem and took a lot of tweaking to sort out including lowering the line voltage to 110V using my 50Hz/60Hz induction motor source.
OTOH the MKI was much less finicky and easier to getting running on speed, it is running on 115V via a step down transformer. (And ran ok on 120V as well, but with slightly more noise.)
The windings on the motors are different, and there may be other slight differences in the motor as well. I am aware of at least 3 major motor variants of the E50.
I am using vintage Thorens belts on both of my tables and this makes a big difference in speed, current belts are all thicker than the original and this results in a shift in the mechanical reduction ratio between the motor pulley and intermediate pulley causing it to run several % faster than it would with the original belt, this taxes the adjustment range of the eddy current brake to the limit. (This issue is more significant on the 60Hz side of the pulley because the increase in thickness causes a bigger error than on the 50Hz pulley which has a significantly greater diameter.) The MKII motor may also produce very slightly more torque than the older motors and the combination of this plus belt and high line sometimes results in excessive speed even with the brake cranked to maximum braking.
The best solution I have found is to reduce the line voltage to somewhere around the middle of the tap's range. Moving to the next higher tap also solves the problem but for some reason seems to kill the dynamics the table is noted for.
The best solution would be a more technically correct belt, but so far I've not found any.
I have two and the MKII has this problem and took a lot of tweaking to sort out including lowering the line voltage to 110V using my 50Hz/60Hz induction motor source.
OTOH the MKI was much less finicky and easier to getting running on speed, it is running on 115V via a step down transformer. (And ran ok on 120V as well, but with slightly more noise.)
The windings on the motors are different, and there may be other slight differences in the motor as well. I am aware of at least 3 major motor variants of the E50.
I am using vintage Thorens belts on both of my tables and this makes a big difference in speed, current belts are all thicker than the original and this results in a shift in the mechanical reduction ratio between the motor pulley and intermediate pulley causing it to run several % faster than it would with the original belt, this taxes the adjustment range of the eddy current brake to the limit. (This issue is more significant on the 60Hz side of the pulley because the increase in thickness causes a bigger error than on the 50Hz pulley which has a significantly greater diameter.) The MKII motor may also produce very slightly more torque than the older motors and the combination of this plus belt and high line sometimes results in excessive speed even with the brake cranked to maximum braking.
The best solution I have found is to reduce the line voltage to somewhere around the middle of the tap's range. Moving to the next higher tap also solves the problem but for some reason seems to kill the dynamics the table is noted for.
The best solution would be a more technically correct belt, but so far I've not found any.