Dragging Motor And Loose Belts Replaced In Sansui Turntable Model P-1000
This Turntable was brought to me with the complaint that gramophone records are not being played properly in both speeds. After cleaning the inside thoroughly, when I tried I noticed that the motor was running erratically, sometimes going at high speeds and sometimes slowly.
The drum has to be lifted up disengaging the belt from the motor through the large holes. The drum has a rubber mat on top of it which has to be removed to see the hole. Let us have a look at the inside of this lovely player:
(Please use cntrl+up scroll of mouse to zoom the pictures, if you want to have a closer look)
As you would have noticed, the player has a motor speed control circuit and a solenoid control circuit to pull the arm back to its stand when the needle reaches last track. All adjustments are done so precisely that if we do not take utmost care, we will end up in a mess! There is a control just behind the arm to choose suitable settings for sliding over the scratchy tracks. This again is an adjustment of the spring that holds the arm down. Unfortunately, unless a video is made explaining these, it would be very difficult for those who are not familiar with Turn Tables. (Perhaps this video which is more of a cat view could explain its working: https://www.youtube.com/watch?v=NhT9W274Mk4 ) I saw two belts wound on the bottom of the drum, which were in fact cut pieces of tubes probably of Motor Cycle or car. This could only be the handiwork of some technician who wanted to increase the diameter of the drum to compensate the dragging of the motor. Since the DC output of speed control IC LA5512 was not stable, I replaced it along with the electrolytic capacitors and potentiometer. The motor was still unstable and was making noise when turned by hand, indicating worn out condition.
As the motor was a common 12V DC that we find in tape recorders, I looked into my collection and found one but the size was a bit larger. In order to test the player, I fixed it and changed the belt to a correct size after removing the patches done on the drum. Lubricated all controls and connectors. Then played the record brought by the customer himself and found it to be working very well. I allowed it to play in full and found that the arm was returning and seating properly in its holder after completion. Then used its function of selecting two speeds. Used the stop button and found it to be working fine. I forgot to mention that I adjusted the speed of the motor for correct play back, as the old Hindi songs were very familiar to me. After this, I went and bought a special tool for cutting a hole at the bottom plate made of cardboard. Placed the bottom cover properly and pressed it down hard on the motor to get a mark for cutting at the precise location. Fixed new legs as the old spring loaded rubber legs were torn and one was missing. Then used a correct size blade and made a hole using my hand drill. Then fixed the cut cardboard piece on the rear of the motor and applied Fevibond around to prevent entry of any pests like cockroaches. Following pictures would make things clearer:
I used IPA and cleaned the records very well before using, as otherwise the dirt in the tracks would cause more load and the sliding of the needle might not be proper.
It might even damage the needle. Here are a couple of pictures more for conclusion with added satisfactions of antique kind to the collection:
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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Waleed Rishmawi
May 7, 2023 at 1:04 pm
I would not even dare to work on such machines because I do not have the parts nor the experience and no devices like that are found in my community any more. Good job my friend and I see that you have replaced some capacitors… the joy continues. Be blessed and thanks for sharing
Parasuraman S
May 7, 2023 at 8:21 pm
Ha! Ha! Many thanks for your comments and encouragement, dear friend!
Albert van Bemmelen
May 7, 2023 at 1:34 pm
Very useful article in the event some old LP/single player turntable needs fixing! Although my Sony direct drive turntable probably still plays very well, it is hardly ever used these days.
I bought my LP/singles record player in the past mainly so I could play back the plastic discs that were included with English C64 computer magazines that stored computer Frequency Shift Keyed recorded programs on them. FSK which was 1200/2400Hz recorded audio code, was in those days also the way how computer tapes stored software.
Parasuraman S
May 7, 2023 at 8:22 pm
Many thanks for your valuable comments and a lot more related information.
NATARAJAN
May 9, 2023 at 10:22 pm
Sri Parasuraman
I recollect working with these type of Turn Tables. especially GARAAD ,HMV and
Philips,Sony Cosmic Bevox.
Thanks for sharing a nice article.
Parasuraman S
May 10, 2023 at 5:09 pm
Yes, it is very interesting to service such turn tables. Many thanks for your share and comments!