Technics Sp10 Woes

Love it or hate it, it just won't stop
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Wolfgang Felber
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#61 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, OK I put a 50K signal from the frequency generator across C1 and C2. Connected the scope probe to PC and P3 and I got a signal, a bit dirty but still a signal. The signal was at 10 volts from the generator. I assume the 1 to 10 ratio on the T1 helps boost the voltage. I am trying to learn this as I go. the 1 ratio winding goes to the base of T28, that is what the schematic say's.
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Nick
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#62 Re: Technics Sp10 Woes

Post by Nick »

Your C1-C2 measurements don't look hopeful. I have just measured a motor I have here

C1-C2 7R
PC P3 9R
PC-P2 9R
PC-P1 9R
AC-A3 13R
AC-A2 13R
AC-A1 13R
F1-F2 224R

So I suspect shorting C2 with ground has passed the 32v supply current through that coil and damaged it.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Wolfgang Felber
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#63 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, that does'nt sound good, what are my options here? apart from a new motor. As the song said, I really " " it up this time.
Wolfgang Felber
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#64 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

There is another option, this is a real labour of love, that would be to rewind those little coils, be a bloody hard job but worth it if you did it right.
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Nick
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#65 Re: Technics Sp10 Woes

Post by Nick »

Yep, that’s about the only option other than a new motor, so if its possible, there is nothing to lose.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Wolfgang Felber
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#66 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick the new coils I am looking at making, they will have to be the same as the other coils, the green or the red . I don't know which one I have damaged. You quoted 7 ohms resistance on the three coils, do you know what the inductance would have to be, I assume the same as the other ones which I can measure. Then experiment with different lengths to get the right reading.
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Nick
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#67 Re: Technics Sp10 Woes

Post by Nick »

I will measure tonight. Simple guess is to find the wire size, then see what length of that gauge will measure 7R, then divide that by 3 and use that length for each coil.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Wolfgang Felber
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#68 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

You make it sound so easy, the hard bit will be getting the former off the laminated steel to rewind it. I have had this motor apart once before and that is how I got it going, the frequency generator coil was broken at the end. I have ordered some 0.02mm insulated wire to do the job.
Wolfgang Felber
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#69 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, OK pulled the coils out, it was the green ones that had shorted. There is 1460mm of extremely fine wire on the coils and blow me down, when I measured the DC resistance of the length of wire, I got 2.4 ohms. that times 3 will give me the 7.1-7.2 ohms you quoted for a healthy set of coils. Am I heading in the right direction? the wire seems the same thickness that is on the frequency generator coil.
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Nick
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#70 Re: Technics Sp10 Woes

Post by Nick »

Sounds like it.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Wolfgang Felber
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#71 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, I managed to wind three coils, what a job. Three pieces of very very fine enamelled wire, 0.1mm in diameter and 1500mm long. I will put them back into the motor assembly tomorrow after the nail polish hardens properly. That is going to be a job as well. I will be wrapped if this does the job. If it works, I will have to find out why it does not lock onto speed.
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Nick
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#72 Re: Technics Sp10 Woes

Post by Nick »

I have my fingers crossed for you.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Wolfgang Felber
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#73 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick,SUCCESS!!!!!!!!!!
Makes a few funny noises but it spins at 33, 45 and 78. I would say it needs adjusting. My coils gave me a total of 10.8 ohms, I hope that will not change things too much. Mate I am wrapped that I got it to this point. How can I ever thank you? You are a legend.
simon
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#74 Re: Technics Sp10 Woes

Post by simon »

Well done Wolfgang, a triumph of persistence. Nick certainly is a legend, I imagine a couple of kegs of beer sent to Halifax might suffice :lol:
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IslandPink
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#75 Re: Technics Sp10 Woes

Post by IslandPink »

A big 'Good Effort' to you - so pleased you got there in the end.
"Once you find out ... the Circumstances ; then you can go out"
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