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Nice one, Martin - glad the Kimber PBJ has worked out well! :)
The improvement it brought with my T/T was quite marked, so I suspect when you play more recordings you're familiar with, you'll realise just how significant this little tweak is ;)
Marco.
while we are on the subject of mains cables, I've just secured me 1.5m of Kimber Crystal 24 which I believe is what is used in the signature powerchord (only £400 for the 1.5m version:eyebrows:). I intend to make into the mains cable for my amp! Already had a spare clipsal (since the last cables I made with Yarbo cable) so now I just need another wattgate for the other end. David do you do any "deals" on them for members?
Also as I was catching up through this thread, I noticed the comments about the earthing and cleaning the gnd connection. Does it make that much difference (my earth is soldered onto the board)? I have access to isopropyl alcohol (my better half is a lab tech!) so I'm going "not" buy some detoxit and set about cleaning all my connections!
Is the gain based purely from the connection of the supply to the board? In which case I'd just advise soldering directly to the pcb or is it to do with grounding the deck casting? In which case, could it be worth tapping an M6 into the chassis somewhere and tacking a decent return?
Again going back through the thread, I've always braided my cables. Having said that, the PJB does represent excellent VFM!
:cool:
Ian, the key point is to use the bottom-left corner of the PCB as that is the earth return point for a lot of the tracks. If you have soldered to it, all well and good as the cleaning advice is only for when using a tag for the screw hole. However, if you have used another location for your -ve return then you may make a small gain by moving it.
OK, my point here is simply that if you have board out and you are fitting a regulator, why would you use the screw down gnd connection and not solder it directly to the board. The primary return would then be via a soldered connection on the main PCB and not the tagged screw connection. I would suggest that the gnd connection to the chassis is also important maybe as a screen to electronics. I would treat this connection as secondary to the soldered path back to the regulator. i.e. single ended and not connecting the regulator gnd to the chassis. I would still look for the best possible connection to gnd for the chassis hence the suggestion of tapping a better anchor point.
I think that makes sense!!! it does in my messy brain anyway!:rolleyes:
I am thinking of the chassis gnd much in the same way that some interconnects use the braid only connected at one end of the cable. i.e. they have 2 cores for signal and return/gnd and the briad is only at gnd at one end and therefore not part of the return path.
Taking it a step further, the chassis could be connected to the regulator gnd and isolated from the pcb??:stalks: a basic start on "star" earth?
Clearly the thought of connecting to "any old gnd" when you have paid for some commercial regulation/PSU upgrades is very much a cause for concern!!!!???:scratch:
Edit- as Paul and his PSU's are tagged in the thread I would just like to point out that I am referring to information further back in the thread relating to some other peoples PSU upgrades and NOT Pauls practice or his PSU's
Maybe if the ground wire is screwed in the corner and the wires from the stock internal reg is cut it makes doing the job much easier (although not optimal) ? I don't think you have to take the pcb out to wire up the lead for the external psu if done the quick bodge way ? :whistle:
For us diyers we can take longer so can afford to rip the thing apart , mines currently wired to allow quick dismantling for trying other mods, once finished the wiring will be re-done as fit and forget , all wires will be soldered onto the pads
de-oxit wipes are brilliant for cleaning all sorts of bits in your hi-fi, and they cost next to nowt! PM your address and I will post you a couple gratis to try.Quote:
Originally Posted by UV101
http://i622.photobucket.com/albums/t...I/IMG_9984.jpg
Hi David
Got the detoxit wipes in the post this morning thank you!
I'll be using them as I unpack and set up in the new house next weekend so timing is perfect!
Cheers!
You are welcome.
Here is some info from Richard peachey (Vantage) regarding the earth tag position.
' The top right mounting screw does not make any contact with the ground return tracks on the main pcb and in fact the pad on the underside of the pcb stands isolated from any other track.. If other external power supply ground return connections have been made at this point, although they will read for continuity to ground, then the whole chassis ground plane will become the reference point and any extraneous interference sources will be introduced into the system (remember I mentioned there are high frequency signals floating around on the underside of the main pcb in close proximity to the chassis). It is entirely possible that if there were any contaminated surfaces (for example between pcb track / washer / screw) these could effectively form a type of junction enough to set up a circuit path with a very slight potential imbalance, enough to create a crude form of tuned circuit and create a source of interference which could result in additional noise injection into some of the reference signal paths '
opps i should have put this in 1st
' Regarding your mention of the "earth tag" I have just had a look at one forum and there does appear to be a lot of waffle being spouted about the grounding point inside the Technics SL-1200MK2. Remember not to confuse "earth" and "ground" as these can have significantly different meanings and functions depending upon the circuit and implementation.
Although the "earth" could be said to refer to the main power supply specifically before rectification (no need to mention "safety earth" here as the deck is built to ISO double-insulated specification) as far as the SL-1200MK2 model goes there is no "earth" point per se inside the chassis. The "ground" can be referred to as the common return path after rectification with respect to the B-plus line and any audio or reference signal return paths. Therefore to all intents and purposes inside the chassis only "ground" should be referred to.
The layout of the PCB has been very carefully laid out despite looking very haphazard at first glance. There are in fact well over 36 critical "ground" points in the main circuit. So messing with these and cutting the circuit tracks willy-nilly are not recommended! If you look very carefully at the PCB tracks you will notice there is in effect a "star" pattern to the ground return tracks - originating at the negative terminal point of C1 (TP4 is the main ground return reference point that should be used for all measurements).
The ground tag that seems to get mentioned a lot is in fact only taking a tap via a short black wire from the ground return track on the underside of the PCB (as the underside of the PCB has a protective conformal coating in place) to the serrated washer on the topside of the PCB and allow the PCB securing screw at that point to ensure a ground return point through the chassis stand-off for reasons other than just a common B-plus line grounding point (there are high frequency signals floating around on the circuit tracks on the underside of the PCB in close proximity to a nice big juicy flat area of the chassis so hence the need to ensure continuity of ground through this post).
Use the enlarged solder pad at the negative terminal point of C1 for any external "ground" return connections.