Hello DIY Community,
I recently got my hands on a pair of SL1210s for a reasonable price.
One of them works fine, however the second one got a slight problem with holding the desired speed when the Pitch Control is at zero or elswhere.
Take a look at the video and you will notice.
Video is taken at 45rpms because it's easier to see at higher rpm.
The "Wobble" occurs roughly once per revolution.
YouTube
I have already searched most of the internet forums (mostly diyaudio.com) and tried a number of things but I'm now asking for expert advice.
I have already checked:
> Pitch Control Fader (works)
> Pitch Control adjustment (exactly @262,1kHz)
> Voltage @TP5 is 21,5V
> Motor coils (not broken/shorted)
> Position sense coils (not broken/shorted)
> FG Coil (not broken/shorted)
> Tested with second platter and problem is still present
As I already tested a lot of things, I think the problem is likely to be the IC201 (AN6680) or the Motor Control IC101 (AN6675).
Can somebody tell me how to verify this?
I don't want to order parts just based on a suspicion.
Thanks and BR!
Gerald
I recently got my hands on a pair of SL1210s for a reasonable price.
One of them works fine, however the second one got a slight problem with holding the desired speed when the Pitch Control is at zero or elswhere.
Take a look at the video and you will notice.
Video is taken at 45rpms because it's easier to see at higher rpm.
The "Wobble" occurs roughly once per revolution.
YouTube
I have already searched most of the internet forums (mostly diyaudio.com) and tried a number of things but I'm now asking for expert advice.
I have already checked:
> Pitch Control Fader (works)
> Pitch Control adjustment (exactly @262,1kHz)
> Voltage @TP5 is 21,5V
> Motor coils (not broken/shorted)
> Position sense coils (not broken/shorted)
> FG Coil (not broken/shorted)
> Tested with second platter and problem is still present
As I already tested a lot of things, I think the problem is likely to be the IC201 (AN6680) or the Motor Control IC101 (AN6675).
Can somebody tell me how to verify this?
I don't want to order parts just based on a suspicion.
Thanks and BR!
Gerald
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Have you replaced the electrolytic capacitors that are in-between the motor control ICs and the motor? That is a common source of problems in Technics turntables.
No, I haven't.
I disassembled the turntable again to look for any other problems and noticed that the motor spindle was not turning smoothly. I lubricated it, turned it a few times per hand and it was already running much smoother. It seems the problem is solved now, no more speed wobbling!
However when I turn off the turntable (with the power switch) it stops much faster than the other one, so I guess it still needs more lubrication or new bearings.
Thanks anyways!
I disassembled the turntable again to look for any other problems and noticed that the motor spindle was not turning smoothly. I lubricated it, turned it a few times per hand and it was already running much smoother. It seems the problem is solved now, no more speed wobbling!
However when I turn off the turntable (with the power switch) it stops much faster than the other one, so I guess it still needs more lubrication or new bearings.
Thanks anyways!
Good to hear it was something simple. All you may need to do now is clean and re oil the spindle bearings.
Pass DIY Addict
Joined 2000
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Rather than lubricate the bearing, remove and disassemble the bearing so it can be properly cleaned. It is easy to remove - only three screws hold the bearing to the chassis. Two more screws allow the bottom plate to come off so you to extract the spindle. Clean each piece, add a drop or two of oil and put everything back together.
When you put the bearing back in, add a neoprene washer (or two) under it so that the bottom of the bearing becomes coupled to the chassis. This will help reduce noise just a bit.
When you put the bearing back in, add a neoprene washer (or two) under it so that the bottom of the bearing becomes coupled to the chassis. This will help reduce noise just a bit.
The entire bearing assembly is quite easily removed (after careful disconnecting some wires, 3 long screws at the motor, pcb board screws) then lift off the whole bearing from under the pcb. Thereon it can be fully dismantled and cleaned up. Only a slight difficulty is a C clip locking the spindle to body. Lightly lubricate the spindle with 3 in 1 oil (Blue bottle - SAE20) and reassemble. If there's no wear, you're good to go. Good luck!
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Pass DIY Addict
Joined 2000
Paid Member
Thanks for adding the images- I was going to do the same today. It is really a rather simple process. The wires on the PCB that need to be moved are all connected by a harness, so as long as you are gentle, this is very easy.
I was just looking at all of the usual sources: e-bay, KAB, and a few others. It seems that the previous supply of original bearings available for $50 has dried up???
I was just looking at all of the usual sources: e-bay, KAB, and a few others. It seems that the previous supply of original bearings available for $50 has dried up???
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