I've been modifying Technics SL-5, SL-Q5 and SL-Q6 turntables to external DC power supply, works great. I fit a 5.5/2.1mm DC jack to the back of the chassis so people can play with "improved" external 24VDC supplies, if that's their bag.
I remove the transformer but leave the bridge rectifier in place to protect against reverse polarity. Keeping AC out of vintage turntables is wise for safety reasons alone.
My favorite supply is the Mean Well SGAS15B24-P1J. A serviced and DC-supplied SL-Q6 with a fresh Technics EPC-310MC cartridge is remarkably capable and convenient.
Cheers, Mike
For my 2 cents worth >
I've noticed that nearly all posts are about improving / 'super-charging' & 'Gold Plating'.
I have never had any complaints of disappointment with my SL-1200.
The part that 'electromagnetic radiation' plays is very much dependent on your cartridge.
In a way - I guess that everything can be improved > at least theoretically.
I'm actually very glad to own one
I've noticed that nearly all posts are about improving / 'super-charging' & 'Gold Plating'.
I have never had any complaints of disappointment with my SL-1200.
The part that 'electromagnetic radiation' plays is very much dependent on your cartridge.
In a way - I guess that everything can be improved > at least theoretically.
I'm actually very glad to own one
I went ahead and whipped out a power supply board after looking at @cbueche boards. I ordered 10, so I have 9 I can share for $13.00 apiece, including shipping, inside the US. These boards are CRCRC with positions for snubbers and an external indicator diode. I used the stock Technics transformer out of the turntable.
I got stimulated instead of going to bed, I soldered the thing and tested it with some random transformer delivering about 16-18V, got a sane DC output, and with some load (100mA) no measurable ripple. All good ! Next is getting the Technics transformer out of the player, finding an appropriate enclosure, etc.
If someone is interested I've got 4 PCBs, what about 13€ delivered to Europe (no tracking for this price...), sounds fair ?
Credit for original schematic and design : 6L6 / July 2013.
If someone is interested I've got 4 PCBs, what about 13€ delivered to Europe (no tracking for this price...), sounds fair ?
Credit for original schematic and design : 6L6 / July 2013.
Attachments
I've got my PSU cabled on a prototype board, waiting for the case, but I do have a few questions:
- using the original transformer, unloaded, it presents 40.5V DC on its outputs. Loaded with 400Ω resistors, it gets to about 36V DC.
- Isn't that too much for the following regulator dissipation ? I intend to use KAB's module (and their strobe switch)
- What current consumption did you measure ?
- cabling of ground :
- the original internal PSU of the SL1200 is 2 wires (N+L).
- I intend to run 3 wires to my PSU metal box, earthing the case
- And then run a two-wire DC cable to the turntable
- earth the turntable using its existing black thin wire
- does this make sense ?
I used only two wires for my umbilical also. I did not ground my power supply to the case. I did connect the EIC earth connection directly to my case. The original turntable had no earth connection, two prong electrical cord. I did use the existing black thin wire to ground my turntable to my preamp. Hope this helps.
Got the 2-wire cabvling done, the regulator installed, and the internals tidied-up. Answering my own question about consumption and regulator dissipation: with my PSU and the KAB regulator, the PSU output voltage drops to about 32V, so the dissipation is in the 2W range, all good for the LM317P and the huge heat-sink that the chassis constitutes. It's now playing Dire Straits Water of Love, and yes I notice a difference in darkness between now and before, although this is not a real A/B test. It takes out the main source of noise from the turntable chassis and that's the goal, it can only be better. No picture yet as the final case hasn't arrived. I need to figure if I pay Schaeffer (aka Frontpanelexpress) to make me a nice panel with the logo, might makes sense as this turntable will be mine for many more years.
P.S. 3 PCB remaining for interested.
P.S. 3 PCB remaining for interested.