OK folks... bearing in mind my previous statements, here goes (my) C3g adapter-making guide.
I'm sorry if it may appear somewhat long-winded but trust me, there are a few things that can trip you up and so need extra care (hence the unreliability of those Chinese ones!) -
I had to learn some of them the hard way...
you don't have to, hopefully!
First, some of the main tools you'll need :
Plus vise, of course...and preferably some kind of 'helping hands' gizmo.
Note the pliers are LONG-NOSED, and small watch repair tools are invaluable.
Now to the parts :
Pic#1...2 pcs cut aluminium (preferably, as non-conductive) Pic#2... 2 LOCTAL sockets - I suggest you buy 4 or more, just
tubing - internal diameter 26.5mm approx. I painted mine... in case! They're not too expensive from the Far East...
Length about 25mm
Pic#3...Stiff plastic sheet (I used an old food container!) to Pic#4...Cut lengths of wire that form the pins - shown here
act as pin wire guide/holder. bare wire (high-quality silver coated copper, or 925 Sterling
silver if you want to 'push the boat out'!). These are part-covered
with Teflon (PTFE) tubing - 2mm internal diameter. If your
amp/extender sockets are well-used and getting a loose fit,
I suggest 1.2mm wire. If still tight, 1mm should be OK. You may
prefer to use plastic coated wire (but good quality, solid).
For later reference, these are numbered 1 to 7 from the left,
and
AT THE LD END!
Construction :
To remove the socket from its holder, I find it easiest to place in the vise (vice!) and lever up the lugs first with a small watch-repair screwdriver, then finish with a slightly larger one...but be as gentle as possible, the ceramic is surprisingly brittle! :
Cut narrow strips of masking tape and wrap around the socket's edge, then mark the pin numbers on it - the numbers can be seen (very faintly!) on the underside, or just remember they run LEFT TO RIGHT CLOCKWISE, #1 starting to the left from the central indent - AS YOU SEE IT, looking down at the underside of the socket. It pays to check, check and check again all through the construction to make sure you don't invert those numbers!
If you have removed the tube from its canister and haven't glued the metal base back on, you will want to use just the base for the rest of the process and I suggest you secure down the socket's pin holders with more tape, as they can protrude up during construction - you can just see an example of this in the above photo. For others, the contained tube will be inserted and will then reduce this tendency.
Ref. pic#2. The socket's centre metal guide has an extension for a ground connection that we don't use, so needs to be removed (as seen in photo)...just hold in long-nosed pliers and bend back and forth, it soon snaps off...Also, as the tube is held EXTREMELY tightly by the guide, I personally open it up a bit by using the pliers as shown below - but the choice is yours! If you do, be very careful once again not to use too much force. The narrow masking tape (with the pin numbers marked on it) around the socket's edge gives some protection.
Now with the whole tube (or just metal base, as below) inserted into the socket, we need to insulate the centre exposed metal parts. I find using the removable fixing 'putty' (ours called 'BLU-TAK') the simplest method, as it is also good for sealing the small holes around the pin connectors (to prevent seepage of the epoxy resin later) :
Then, I like to prime the connector tabs with solder.
Now we need to prepare the wires as per pic#4...to make life a bit easier, I have shown the rough shapes they can be bent to, remembering the numbers relate to the LD end, 1 to 7, left to right (of course I should have arranged them as at the C3g end, since that's where they're soldered - a senior moment, lol! So PLEASE keep referring to the equivalent C3g number when positioning for solder).
The wire lengths should be roughly as : (LD) pins #3,4,5&6 - 35mm; #1 - 32mm; #2 - 38mm; #7 - 39mm. Plus you need a short piece to connect
C3g pin tabs 2 & 7 inside the socket.
Oh dear...am running out of time and nowhere near finished, so I'll have to part post this and continue after dinner - sorry! (If you haven't already given up anyway!
...(Haven't found how to just save work here, yet...). So BFN...
Right, that's dinner out of the way so it's back to work.
So with wires at the ready - those with conventional wire will of course need to bare the bent (solder) ends, and strip to leave about 10mm covering beyond these ends (the photos will give you a rough idea) - I find it useful to also prime the bent ends with a little solder.
Now it's time to solder the wires to the socket tabs...and this is where those 'helping hands' flexible grips come in REAL handy ('scuse the pun!). Remembering to CAREFULLY convert the wires' LD pin numbers to the C3g equivalent, solder them so as they all SPREAD OUTWARDS, as per the photo - the idea being that when you push the soldered tabs forward they will be close to the required new position (with some manipulation needed later, that is!). And remember the short 2-7 C3g internal connecting wire will join with that to the LD at C3g #2 :
The pin routing is as follows :
LD C3g
1 - 6
2 - 5
3 - 8
4 - 1
5 - 3
6 - 4
7 - 2
7 connected to 2 inside socket
If you haven't already, I now suggest you cover the tube canister also (not shown above) with masking tape, for protection from any resin yet to come!
Next, it's time to push forward (and over where necessary) the soldered tabs, making sure the joins are really secure - the pushing and pulling will soon show up any that aren't!
By studying carefully just where they need to go to match the LD pin positions, hopefully you won't find it too hard to manipulate the wires to roughly where needed, and the long-nosed pliers will be vital in the bending needed to finally get the positions just right.
A bit more of an idea can be got from holding the LD pin holder (more info on it below) above the socket as a guide :
nb...don't forget to mark the correct corresponding numbers on the underside of the plastic, because when you look at the underneath for positioning it's easy to get confused due to the 'inversion' factor!
KEEP CHECKING the C3g numbers are going to the correct LD target numbers...you can't be too careful...
Better late than never, a look at these pin holder/guides - ref. pic#3. Although other items can be used - like cut pieces of circuit board or 7-pin straighteners, if you can find them - because of the need for gaps to pour in the resin, I have found it fairly easy to cut to shape pieces of thin but stiff plastic (like that used in food containers).
As in the photo, this can be done by drawing a circle to the same diameter as the inside of the case, marking the pin positions in the middle (for example by dabbing some ink/paint to the ends of an old tube and applying, or making a paper stencil of the same size and pushing the pins through to make the required holes for stencilling onto the plastic), then drawing the triangle to just clear the holes. Now drill the holes (2mm drill bit for 1.2mm wire, and perhaps a 1.5mm bit for 1mm wire, you can always increase the size if necessary) - keeping as vertical as possible. Finish by cutting it out (carefully, please, if using a Stanley knife!), and trim to fit inside the case.
(Will post this last section before it freezes on me again, and continue after...)
Right now...where was I?...can't blame the page for freezing on me (again!)...wouldn't blame
you either...but perhaps if you digest bits at a time and mull over what's involved for a few days, you might just feel like giving it a go...
Anyway, by now the pin wires are hopefully just about in position enough to work through the holes in the guide - cutting them to equal length (not too short, yet!) and using a pair of tweezers should help, plus a good dose of patience. Be
ABSOLUTELY SURE you have aligned the pins correctly through the holes...check, check and check again. At this point, when you push the guide down to its final resting place, just below the top of the case which is slid over and onto the socket, you will see just how near the middle you've managed to position everything (the case may just need a forceful push to sit flush on the socket - the degree will indicate how far out you may be). This will give you an indication of where you may need to do some last minute bending at the lower end of the wires to correct things, and with the case removed you will also see how true the wires are vertically...adjust to the best vertical you can manage :
As you can see, I had some more adjusting to do!!
With all adjustments finished, you
MUST make sure there is no metal to metal contact ANYWHERE...check especially where the soldered tabs are bent over the covered central dome - if necessary pack with more of the Blu-Tak (or equivalent). And where wires have to cross. Make sure also the casing is well clear of the bent tabs when placed onto the socket - if in any doubt at all, form a ring of insulating tape around them. While at it, check also the 'putty' sealing the gaps at the base of the pin connectors/tabs - it's probably come loose after all the manipulating...
It would be wise to check with a meter that you have continuity from socket to pins - this would also act as final confirmation you have routed the pin wires correctly. Failing this, at least make sure all the solder joints are still secure.
Slide the case back over, and while holding it flush to the socket wrap tightly with masking tape, making sure it seals well at the join.
Now it's time to prepare for filling with epoxy resin...
Oh dear, time has run against me again...afraid I shall have to finish this tomorrow.
Good night all (if you're still awake, that is!)...as I said earlier, please digest all this in bite-sized pieces...
OK...let's get this massive missive done and dusted, lol...
I suggest that if only the tube's metal base was used, as opposed to the whole thing, you check the top of the socket and make sure none of the pin connectors has been pushed up and standing proud - just push 'em back down if they have before filling with resin (you might also want to check the base is flush up to the socket - if not, remove and replace the masking tape while holding the base in hard...you don't want too much of a gap here, as the tube's pins are not very long).
And so, with the plastic pin guide/holder just below the case edge (and the pins hopefully looking fairly straight!), run some masking tape around them, flush with the case's edge :
You're almost there now, folks...give yourselves a pat on the back for having got this far(!), and get mixing that 2-part epoxy resin. I suggest that unless you're used to working fast with the 'rapid' version, you use the ordinary type that takes longer to cure...you'll just have to be a bit more patient, lol! I use this type of 'glue' because it flows nicely into all the tight spaces inside the case and seals everything like almost nothing else can - and, like, PERMANENTLY once cured!...which is why it really is a good idea to do that checking with a multimeter before this irreversible stage (although you
can always cut the case and smash the innards with a heavy hammer if worse comes to worse!!).
I find my tubes of resin - about 24 grams combined - enough to do the job, and I suggest you mix it in a small, shallow (but not
too shallow), square or rectangular plastic container that will allow you to be fairly precise in pouring through the gaps formed by the pin guide (perhaps with the help of a small spatula or old screwdriver, for example). Filling to just about the top of the case should cover the guide and the small area of pins between it and the tape (hence the need to place the protecting tape FLUSH with the case edge) , thereby securely finalising the position of the pins.
When finally set, remove the ring of tape, making sure no resin has crept up the pins - if so, just remove with a Stanley knife. Then trim the pins to about 8mm (better a little more than less) and smooth the ends with a small file - preferably to a slight, rounded point, to aid insertion...(I find my wire cutter sometimes pushes out the edges - if so, make sure you remove the protrusions with extra filing).
All this will probably push the pins slightly out of position, so check with another pin guide; up against the base of an old tube; a 7-pin socket or straightener if you have one, and readjust if necessary.
If you have been working with bare hands all the while, there's likely to be a load of grease on those pins, so I suggest cleaning them with something like isopropyl alcohol, or white spirit followed by a damp cloth.
Now all that remains is to remove the masking tape - while breathing a great sigh of relief! - and plug the darned thing in...I suggest removing any extender and then plug the adapter into it, just in case a certain amount of 'wiggling' and careful use of force is needed - especially if the larger 1.2mm wire is used. Not only will this be easier away from the amp, but will reduce the strain on the amp's socket - I feel those sockets (
and PCB) are not mounted all that strongly!. Those with the bare tube now need to be VERY careful when inserting into the adapter - not only re correct alignment into the metal base, but because it can be an extremely tight fit, and may need careful, but quite forceful, working in of the pins...so
TAKE EXTRA CARE!
Hopefully all is well as you power up - and they actually WORK?!...Whereupon you will, no doubt, wear the biggest smile (almost!) of your life...
... As I mentioned previously, all the better if you test first with a cheap used tube -
just in case.
So there we have it...a project I don't doubt has put some (if not many!) of you off the whole idea...BUT...if you do have the basic skills necessary, it won't seem so daunting if you take your time and go over all that I have covered here a good few times, and allow yourself plenty of time to get all the necessary bits (and tools) together, and start making the various components slowly, one at a time - don't try to rush things...you may well become frustrated and disheartened. If necessary practice some of the procedures a few times to gain confidence - and hone your soldering skills as best you can. The end result will be MORE than worth it, when you can enjoy the magic of the C3g tube...not to mention the immense satisfaction from achieving such a goal.
I wish you all the very best in the event you do bite the bullet...at the very least, this has shown just what is involved in making these things, lol!
.
(Perhaps MIKELAP's offering will be more straightforward than mine...we wait with eager anticipation!).
CHEERS!
ps...By the way, if you didn't catch the finished article in a previous post, this is how they can look...:
What I was getting at ultimately asling for the 5687: Could the 5687 be ranked on a similar level as the 6SN7?
