Technics Sp10 Woes

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Nick
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#16 Re: Technics Sp10 Woes

Post by Nick »

The pulse streacher cap after it should avoid the problem. I think you need to look at the logic signals with a scope now to see what’s going on.
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Wolfgang Felber
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#17 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, long time no talk, good news on my side, got the SP10Mk2 going. the problem was a broken wire (very fine wire) located inside the motor which sends a signal back to the, I am assuming the PLL. suffice to say after a long job pulling the motor apart and locating the end of the wire and re-terminating the wire and putting it all back together, away she went, now giving me speed control. I still have to get the ON/OFF switch to be more positive, I have been using different value resistors on the IC 8. Have'nt got it right yet, still getting double clicks and sometimes wont switch off. I also have replaced the strobe light. God I have spent some time on this thing, hate to be paying the labour cost, nearly 60 hours.

Regards

Wolfgang Felber
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Nick
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#18 Re: Technics Sp10 Woes

Post by Nick »

Cool, well done
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Nanook of the North
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#19 Re: Technics Sp10 Woes

Post by Nanook of the North »

Well I tip my hat to your perseverance lads, but I would have took a hammer to it and bought a new 1210.
trentonisla
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#20 Re: Technics Sp10 Woes

Post by trentonisla »

Have you tried removing the C202 near IC?

As nick said it is part of the pulse stretcher circuit, removing the el cap will bypass this feature. Newer IC are fast enough thus not needing those pulse stretcher anymore. Give it a try.
Wolfgang Felber
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#21 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, I dont know if you read my last post, but I have had a massive fail, tried testing the 50k herz oscillator circuit and something went pop. blew the 32.5 volt fuse and all I get now is the solenoid for the brake clicking. Nothing else apart from the main driver transistors getting real hot. I have read about using scopes and the ground connection being connected directly to the main earth. I think I have created a short circuit somewhere along the line. I know I am pushing my friendship but would you have any idea where to start looking for damaged components. I have ordered a pile of transistors and diodes to replace whatever I find. I havent tested the crystal yet. is that something that could be affected. at least you can still buy them , not like some of the transistors. I am realy desperate to get this this back up and running.

Kind regards
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Nick
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#22 Re: Technics Sp10 Woes

Post by Nick »

The problem is you may well have shorted the 32v line to the 5v line and taken out all the logic chips. I did this and had to replace the lot. I would start with that, maybe remove the 32v line (not sure if the logic board will run on its own), but if the driver transistors are running hot you could kill the motor.

It may be time to seek local professional help as you are now facing a very steep hill.
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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#23 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, how do I test the motor to make sure I have'nt destroyed it? I did put the multimeter on ohms and measured the motor from AC to A1, AC to A2 and AC to A3 they all read 14.5 ohms across them all, is that OK or have I destroyed the motor. If that is OK, then I can sigh with relief and continue to try and fix it. if not, spare parts for someone and I would be heart broken, this turntable can get under your skin, its got me hooked. I actually got it going from nothing,so I would be really annoyed if it was all for nothing. I like you replaced all the IC's on the logic board, so I have a very appreciation of what it takes to get this thing up and running.
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Nick
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#24 Re: Technics Sp10 Woes

Post by Nick »

That sounds hopeful for the motor. You are facing the double problem that you are repairing a non standard sp10, so much of what I know is not applicable. If you did replace the logic, hopefully you used sockets?
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#25 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, I certainly did, and I have spares of the chips, so I will start there. I checked the Crystal oscillator last night and that seems to work OK 3.579 mega hertz. How do I test the other oscillator circuit? the 50K Hertz circuit using T1 and Tr28. Just out of left field, can one return the SP10MK2 to the standard by removing the other circuit board. Can you think of any benefit of having it? If and when I get it going again, I take on board what you are saying and will take it to a professional to set it up on a scope.
regards
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Nick
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#26 Re: Technics Sp10 Woes

Post by Nick »

can one return the SP10MK2 to the standard by removing the other circuit board.
I have no way to know, sorry.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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#27 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, I worked out how to bring the SP10MK2 to original format. The ABC mod was just for the cueing of the deck. It is back to original. Now I am still trying to get it going. I replaced all the IC chips but that made no difference, the driver transistors are still getting very hot and there is no movement. Open to suggestions.
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#28 Re: Technics Sp10 Woes

Post by Nick »

Not sure what to suggest. May be measure all the voltages on the driver transistors write them on the schematic and we will see what looks wrong.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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#29 Re: Technics Sp10 Woes

Post by Wolfgang Felber »

Hi Nick, I have just about completed testing all of the transistor and diodes. I will send you the list. I am also taking measurement of all of the IC chips from each pinout. I have also got a full compliment of transistors and IC's to replace anything that is faulty. I am ready to go but not sure which ones.
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#30 Re: Technics Sp10 Woes

Post by Nick »

Do you know what you shorted to what? that may give some help which bit swill die.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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