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Post by atnegam on Apr 15, 2015 19:41:20 GMT
Hi everybody! I have recently decided to change power cable running between my good old X-CAN v3 and X-PSU v3. As I understand, center pin on 3-pin DIN is GND, and side pins are +12V. Barrels of a DIN plugs on standard MF cable are N/C and cable is unshielded (correct me if I'm wrong). Currently I'm reading a lot of articles on various DIY forums about shield-or-not-toshield power cables. Most articles say that if you had to shield your cable, then shield should be connected to GND pin only on one end of the cable (at "source" end). For mains cable it would be the end that goes to power outlet. But on MF X-series we have DIN plugs with barrels. On X-CAN v3 on the socket side barrel is connected to common GND. On X-PSU v3 on the socket side barrel is N/C. So where to connect shield? To the barrel on the end of the cable that goes to X-CAN? Or to the GND pin on the end that goes to X-PSU? As far as I know, PinkFloyd have already solved this problem in his own cables: www.rock-grotto.co.uk/xpsuv3pinkcable.htm - amirite? Could you please share your solution? Also, if anyone here have that pricey RAL "Passage Cryo-Silver™ Reference umbilical power cable" - could you test with multimeter how DIN barrels are connected (to each other / to GND / or not connected)? Thanks  |
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Post by atnegam on Apr 24, 2015 14:08:53 GMT
Bump!
I can't believe that no one knows about proper cable shielding.
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jc
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Post by jc on Apr 24, 2015 17:34:12 GMT
Are you actually suffering from RF interference over the 12v-0-12v line connecting the PSU and the Can?
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Post by Deleted on Apr 24, 2015 22:03:14 GMT
Bump! I can't believe that no one knows about proper cable shielding. Don't jump to conclusions. Properly designed equipment shouldn't need screened power cables, whether AC or DC. Mains cables for example should be kept well clear of interconnects, (even double screened coaxial construction types) and cross them at 90 degrees. There are other measures that reduce sensitivity to various types of mains cables such as a "snubber" across the secondary windings of the transformer. A typical value could be 22nF and 330 ohms in series.
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Post by atnegam on Apr 30, 2015 13:58:56 GMT
Are you actually suffering from RF interference over the 12v-0-12v line connecting the PSU and the Can? Nope. Just wanted to know how to make cable shielding properly. Connect shielding at both ends of the cable? Connect it to barrel or GND pin of DIN plug? There are other measures that reduce sensitivity to various types of mains cables such as a "snubber" across the secondary windings of the transformer. A typical value could be 22nF and 330 ohms in series. Could you please provide an example scheme for this "snubber"? X-PSU's transformer has dual secondary windings which are connected to make a center-tap. Where should I place capacitors and resistors? |
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Deleted
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Post by Deleted on Apr 30, 2015 22:17:34 GMT
Simply join one lead of the capacitor to one lead of the resistor, and connect the other 2 leads across the outer (unjoined) leads of the 3 secondary wires.
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Post by atnegam on May 4, 2015 12:12:54 GMT
sandyk, so the scheme should look like the (1) on the picture below? Also I saw similar scheme but with separate snubbers (2). Which of them is right for X-CAN v3?  BTW, still waiting for any useful comments on cable shielding problem.
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Post by PinkFloyd on May 4, 2015 19:11:15 GMT
You have a three wire cable with a shield? Connect one of the wires AND the shield to the OV secondary on the transformer but don't connect the shield to the Middle pin of the 3 pin DIN plug..... it's as simple as that.
Hope this helps,
Mike.
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Post by atnegam on May 4, 2015 20:24:56 GMT
Mike, thanks for clarification!
In case of DIN-to-DIN cable with shield (I intend to use it with X-PSU), should I connect shield to GND pin on just one side of the cable?
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Post by PinkFloyd on May 4, 2015 21:33:11 GMT
Mike, thanks for clarification! In case of DIN-to-DIN cable with shield (I intend to use it with X-PSU), should I connect shield to GND pin on just one side of the cable? Yes, connect it at the transformer secondary (0V) and leave it floating at the 3 pin DIN end..... ie: don't connect the shield to the centre pin of the 3 pin DIN plug. As Alex has already said, it will make little (if any) difference but will certainly do no harm..... 24VCT (12-0-12) is 24VCT (12-0-12) all day long and if you fit a string of diamonds onto the cable it will STILL be 24VCT (12-0-12)....... leave it to mature for 35 years, coat it in varnish or deep freeze it in a cryo thing and you will STILL have the same 24VCT (12-0-12). The secondary "shunt" that Alex suggests is a far better area to be concentrating on...... you really won't gain anything by shielding the 12-0-12 output from the secondary...... Nothing to stop you doing it though and it will, most certainly, not have a detrimental effect on the SQ.......It will be as effective as painting a toilet with gold paint...... you may "think" that you are crapping "royal" (odourless) turds, what with the gold shitter, but your turds are still common or garden turds..... 12VAC works much the same way....... 12VAC will always be 12VAC, unless you lick the outputs with your tongue and experience the "tingly tongue" effect, and cause a fuse to blow. I'm late to the party on this thread (sorry about that but I have a life) and need a bit more info about just WHAT problems you are having with 12V AC and what you hope to achieve??? Pinkie. |
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Post by Deleted on May 4, 2015 21:54:23 GMT
sandyk, so the scheme should look like the (1) on the picture below? Also I saw similar scheme but with separate snubbers (2). Which of them is right for X-CAN v3? BTW, still waiting for any useful comments on cable shielding problem. Highly experienced E.E. John Swenson, who designed the improved replacement for the Squeeze Box Touch which featured in DIY Audio etc. and the very well received JS2 Linear PSU for the Mac Mini, recommends as per figure 1 for most transformers. I doubt that using a screened cable for supplying power as you discussed is likely to make any worthwhile improvement unless the power supply area of the powered device is very poorly designed. |
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Post by atnegam on May 7, 2015 18:04:24 GMT
Mike, sandyk, thanks a lot for the help!
I think I'll put aside my idea of adding shielding to cables and instead do more research on those "snubbers".
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