How to Connect an External Dc Supply to the SL-1200/1210

[MCRU]

Why are the audiophile PSU's so expensive, £300+ is ridiculous?

[Reid Malenfant]

Design & build your own, it's what i'll eventually do

With all the components i have here i'll probably only need to buy a case to stick it in

[MCRU]

Sounds like a plan, I have lots of boxes too! Perhaps you can build one for me in exchange for a some mains goodies?

[Reid Malenfant]

Sounds like a plan, I have lots of boxes too! Perhaps you can build one for me in exchange for a some mains goodies?

David, you'd have to have the patience of a saint i'm afraid

I have a number of projects in development (mostly in my head right now) that are on hold simply because i have nowhere to actually get the bloody work done I'm working on that though & gradually clearing a room so i can make a workshop

You might know how things conspire to make things difficult No car license means i can't simply fill a car with crap & take it to the dump... A buggered up back means i can't go mad & hire a skip & attempt to fill it quickly as i'll be on my back before it'd be half full

It's great to be alive though

[Ammonite Audio]

Why are the audiophile PSU's so expensive, £300+ is ridiculous?

Not really, if you accept that someone's got to make a living out of selling these things, unless that someone is obviously taking the pi$$ with just a handful of off-the-shelf components that only cost a few quid. If you ever get a chance to look at a Paul Hynes SR3 or SR5 PSU, you'll probably wonder how he does them for the money!

[sonddek]

I just re-soldered my Timestep lead and attached it to the real earth instead of the top right corner.

I note that the diagram on the previous page is a view from underneath the circuits. Realising that, I have just applied a much cheaper power supply mod to my second deck. I am using the original power supply, but in an external box. It supplies AC to the two AC posts at the bottom left of the circuit (when viewed from in front of the deck and above it). All seems to work fine. I can't say I notice a huge improvement, but it can't hurt to get the transformer out and away from the deck. I also just replaced the arm with a new stock one. It sounds pretty good as a stock deck, albeit with a Stanton headshell and Goldring 2100, playing into a Uphorik. The frequency extremes aren't impressive, but that's the cartridge. Very very musical though. All in, an amazing deck for 300 quid.

[Marco]

Hi Richard,

Realising that, I have just applied a much cheaper power supply mod to my second deck. I am using the original power supply, but in an external box.

Nice one - I've often recommended people to do precisely that who may not have funds to buy a Timestep or a Paul Hynes PSU.

Any chance of some pics of what you've done, and a detailed description of the procedure involved?

It would be a useful addition to the thread for people to use for future reference

Also, do pop in more often, as I enjoy reading your posts on pfm. It would be good if you integrated more into our community, giving us your erudite views on the SL-1200 on a more regular basis

Marco.

[sonddek]

Nice one - I've often recommended people to do precisely that who may not have funds to buy a Timestep or a Paul Hynes PSU.

Any chance of some pics of what you've done, and a detailed description of the procedure involved?

Here are some images then:















I advise anyone who is not very clued up about electrics NOT TO DO WHAT I'VE DONE HERE, as there is plenty of scope for killing yourself or burning your house down when everyone has gone to bed.

That said, the goal is to provide 29V AC to the logic/drive unit at the two binding posts. You can see that I have soldered a cable to the posts in picture 7. Technics doesn't solder these terminals, but winds the wire around them many times. I don't know why they do it this way, but I don't doubt anything their engineers have done.

The three chunky mains power cables which go to the on/off switch have just been cut and terminated. There's no need to terminate them though, they carry no voltage.

The blue cable I used is almost certainly the wrong kind. I just guessed. It came from Maplin just like all the other bits I used.

It is VERY IMPORTANT when putting together the transformer box to remember safety. I always put saftey third. I end up with zapped equipment, burns from the iron, stuns from the mains and so on. I will probably also burn my home down. Don't f**k with mains electrics, it's not a toy. Observant viewers will notice in these pictures that I have blown the fuse on the circuit board. Don't do what I do.

I put the live main to the switch. I doubt that's safe, but I wanted another way of turning off the device than just unplugging it, in case the plug is hard to reach.

Since the deck's power knob has been removed from the circuit, it is necessary to short out the two terminals that the switch connects. You can see I re-used a bit of the pale blue mains wire for doing this. I shorted out the switch in such a way as to keep all the fuses in the circuit.

The mains wires ought to be wrapped around their terminals, not just soldered to them, as solder is brittle and breaks very easily when things are kicked around. You don't want live mains invigorating the socket or switch and reminding you what 240V feels like. Or burning down your house.

The circuit board is levitated from the base by using three nuts on each bolt: one to lock the bolt to the box, and the other two to lock the circuit on the bolt some distance above the box base.

The AC output from the transformer goes to a fuse on the power circuit board, and emerges again as a small blue wire, so we have one yellow wire direct to the 29V output socket, and one blue one. I wrapped those in a lot of insulating tape in the hope of avoiding the firework display which would result from shorting the mains to the output accidentally.

Finally I re-used the rubber grommets which act as feet for the transformer, and made sure everything was bolted firmly to the box so nothing flies around inside. Remember, safety third.

Shielding is not very thorough as the cage around the transformer has no bottom. In the deck it doesn't need one since the alloy chassis shields it at the bottom.

Next time I do one of these I will probably do away with the switch and the socket, and just run both wires in and out. It'll take less time, and probably be safer and better.

[Mike_New]

Wire wrap was used extensively in very complex logic circuits, before the advent of multi-layer PCB technology, where as many as 400 integrated circuits were employed on a common board. With as many as 14-18 pins per IC that amounts to 7,200 interconnects!!! The wire when wrapped around the corners of the pins, (you will note thay are of square cross section) forms a type of pressure weld at the corners for excellent contact. It was later adopted for more mundane applications where the cost and time of soldering could be avoided. You can affect a ww joint in about 1.0 secs
In the imges shown, the wire should have been wrapped around the terminals a couple of times for machanical strength, before soldering.
Never solder a heavy wire carrying current as a parrallel joint as shown it can easily be pealed off!

[sonddek]

Wire wrap was used extensively in very complex logic circuits, before the advent of multi-layer PCB technology, where as many as 400 integrated circuits were employed on a common board. With as many as 14-18 pins per IC that amounts to 7,200 interconnects!!! The wire when wrapped around the corners of the pins, (you will note thay are of square cross section) forms a type of pressure weld at the corners for excellent contact. It was later adopted for more mundane applications where the cost and time of soldering could be avoided. You can affect a ww joint in about 1.0 secs
In the imges shown, the wire should have been wrapped around the terminals a couple of times for machanical strength, before soldering.
Never solder a heavy wire carrying current as a parrallel joint as shown it can easily be pealed off!

Thank you very much for the info Mike. I will go back and do it again, properly this time.

P.S. I'm still saving for a bearing. Hopefully will paypal you soon.