Gramophone is one of the best invention human made till 20th Century. But after so much invention in audio industry, no other device could replicate the depth and quality of music played from Gramophones. I had a Gramophone of 1950s, purchased by my grandfather. It was very close to my heart, but it stopped working from 2006. We went to every other shop which repair Gramophones, but in vain, it couldn't get fixed as the parts of that Gramophone was stopped manufacturing. Then we kept it in the shelf. Fast forwarding to 2018 when i was studying engineering, i tried to repair it and accomplished it which professional repair person couldn't do by using jugaad (A flexible approach to problem-solving that uses limited resources in an innovative way.)
Step 1: Finding What Is the Problem
When i plugged it and played, the main light glowed but the disk didn't rotate. Concluding either motor is out of order or the circuit has a problem. I checked with multi-meter the continuity of the motor, and the multimeter didn't beeped, hence concluded there is a problem with the motor. I went to shop to purchase similar motor but couldn't get the same motor as it was not being manufactured. So i purchased a local motor. I also checked the continuity of the speaker, but here as well the multimeter didn't beeped. So the speaker was also not good.
Step 2: Fixing the Motor
I placed the new motor in place of the original motor and fixed with the same wires. But as soon as i switched the Gramophone on, the disk was moving very slowly. As it was not the same motor it was not moving as same speed. and in gramophone constant and similar RPM is very important otherwise either the music would be played in slow motion ( as in my case) or fast motion.
Step 3: Solve Speed Problem of Motor
Speed of a DC motor can be varied by varying flux, armature resistance or applied voltage. Different speed control methods for different DC shunt and series methods are there. The easiest among them is to change the applied voltage to the motor. The voltage is changed by using a boost converter with inbuilt potentiometer to change the voltage according to our wish. Connect the Components as given in the figure. Capacitor is used to make the voltage constant as much as possible so that the disk speed is constant. After making the circuit i placed all things in position.
Step 4: Testing
I tested it by adding a jbl speaker from the original speakers input but the volume was very low and sound quality was also very bad
Step 5: Fixing Speaker Problem
I thought rather than adding another small speaker, why not give the output of gramophones amplifier to my home theater speakers to get better sound quality. I also purchased another Philips needle form the website ( https://ngh.co.in/philips-needle.html ) and Attached to the gramophone.
Step 6: Fixing Sound Input
I attached the input of home theater to the main output of amplifier.
Step 7: Putting the Booster
I drilled the the front part of gramophone and attached the booster by using screws. I placed booster outside so that we can calibrate the speed of disk by using a screw driver and rotating the knob from front.
Step 8: Finished
The gramophone has come to life and is working perfectly