Pass DIY Addict
Joined 2000
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Glad to see you've made some progress. Your image differs from mine: you have red and yellow wires on your transformer, where mine are blue and yellow. The secondary is yellow on mine - but you've already figured this out.
To answer you question about a fuse: YES!! ALWAYS use a fuse. You don't know what can go wrong and without a fuse, it can always get worse!
To answer you question about a fuse: YES!! ALWAYS use a fuse. You don't know what can go wrong and without a fuse, it can always get worse!
Pass DIY Addict
Joined 2000
Paid Member
A few general ideas that may have benefit -
1) In my experience, the advantage of this PSU mod is mainly (90% ? 95% ?) removing the EI transformer from the chassis and 1M away from the cartridge - this does two things, a) removes the physically vibrating transformer front he chassis, and b) removes the EM field from same transformer away from the cartridge.
2) Regulators should be close to the load. The internal discrete regulator already on the PCB works quite well, changing it might be beneficial, but it’s going to be mild at best.
3) The umbilical from PSU to turntable should be DC
4) I have not experimented with SMPS specifically in regards to SL-1200, but I suspect it would work quite well, as long as it’s removed from the chassis. Having a switch mode regulator regulator in the chassis seems like it would be less noisy than the entire supply, but experimentation seems in order.
Summary - (no new information here...) The sonic advantages of this mod are huge when the PSU is removed from the chassis of the turntable.
Having fitted numerous different external PSUs to the 1200/10, I can confirm that you're right on all fronts. It must be approaching 20 years since I first fitted one.
Carts vary quite a lot in their abilities to screen EMI. I made a little video, with a normal AT MM cart feeding a conventional MM preamp, hooked to a live FFT. As the arm progresses across the record, you can see the 50Hz increasing as it gets nearer to the transformer.
Similarly, the EI transformers vary in terms of their mechanical and radiated noise. However, with many of the Technics ones, you can hear it hum if you put your ear nearer the platter. I've seen one or two that were seriously noisy, to the point where you'd hear them in an external enclosure.
I always keep the internal VReg, and see no plausible reason for not doing so. I haven't been able to discern any performance difference with linear vs SMPS, either. I actually feel that SMPS could offer a benefit (assuming it's designed properly and meets FCC / CE regs). I've fitted both type and am happy to listen with either.
I cut the orange and brown wires that go to the connector on the pcb. That didn't work. Apparently, the schematic is unaccessible on VE
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...even if Ken here:
My Second “Techie” – well all of it! - Page 4
says that for best benefits it is better to remove the switching transistor from the board rather than simply cut the strobo light with a switch.
My Second “Techie” – well all of it! - Page 4
says that for best benefits it is better to remove the switching transistor from the board rather than simply cut the strobo light with a switch.
