Technics SL-1410 MK1(?) problems

turning japanese
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Joined: 15 Sep 2019 14:54

Technics SL-1410 MK1(?) problems

Post by vinylproblem » 15 Sep 2019 15:05

Hello there.

Yesterday i went to my dad and borrowed his old technics turntable.
The model says SL-1410 but does not look the way the instructions manual on this page pictures the turntable... So i guess this is a mark 1.

I connected it to my amp, and turned on the first record some old Alice Cooper, switched it to the record i wanted to listen to.

Compared to the cd, the songs sounded a bit slow, specialy the voice sounded a bit of in time, so i flipped the swith to 33 rpm and after that the turntable no longer spins. I can hear a "click" when i move the tonearm to the record, the light lights up but the motor isnt moving the table.

Something is wrong i guess? Anyone who knows this turntable and is willing to help me?

Posts: 78
Joined: 20 Aug 2016 12:54

Re: Technics SL-1410 MK1(?) problems

Post by Tom_Technics » 21 Sep 2019 00:07

Firstly, open the turntable according to the instructions in the service manual and clean the pitch control potentiometers with a contact cleaner. De-Oxit is the best followed up by De-Oxit Faderlube to replace the lubrication in the pot which prevents wear to the carbon track. You should also clean the pitch range adjusters on the drive circuit board.
If you have some deep sockets and a ratchet, I advise removing the pitch control knobs and disconnecting the pots from the chassis. This way, you can position them outside the turntable in order to prevent spilling contact cleaner inside. Similarly, if you're handy with a soldering iron, it's a good idea to remove the pitch range adjusters from the circuit board, clean them outside of the turntable and re-install them. Do not use lead free solder.
Secondly, the speed selector switch should be disassembled and cleaned thoroughly with isopropyl alcohol soaked q-tips/ cotton buds, then re-lubricated with some Faderlube although this is not as important for the switch as it is the pots.
This is the simple fix. Unfortunately, the Drive Circuitry of the SL-1400/ 10 utilises the failure prone 2SC1318 transistor. Failure of this can cause all sorts of problems so, if you can solder, I highly advise replacing both transistors and, also, all of the electrolytic capacitors.
The bad news for you is that your symptoms sound like they could be down to a faulty transistor. Dirty controls usually cause speed fluctuations although a seriously dirty Speed Selector Switch can cause the no rotation symptom. A bad voltage regulator component usually causes the turntable to spin slower, faster or not at all but not usually speed fluctuations. If TR2 2SC1318-R has failed, there is a likelihood that the IC is now also damaged. The usual symptom for this is either no rotation or the platter rocking back and forth.
Of course, don't go this deep if you have limited electronics knowledge and are not confident about learning. Fixing a turntable is a good place to start for this stuff although you still have to be careful of line voltage when testing. Testing a speed control circuit is very safe for a beginner as the voltages and current will be nowhere near lethal levels.
Cleaning the controls and disassembling the speed switch are fairy easy tasks. You have to be mindful of the small contacts in the selector switch and note which way they go back in (take a photo), but it should be fun work for patient and careful hands.
Let me know how you get on.

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