Need Vox 847 power jack wiring diagram. Anyone can help?

[jimlam]

Hi guys,

I've done the various mods on the vox 847 and love it but am now left with adding a dc power jack. I'm planning to wire it such the the effect is powered by the dc jack when it is plugged in and by batteries when the power jack is unplugged.  I tried my best to understand the schemetic but cant really relate it to a vox wah circuit.

Anyone has a wiring diagram or pictures of how its done? I would like to know basically which wires to cut and what to add to where. Can anyone provide assiatance. Any help would be appreciated.

Thanks.

[formerMember1]

IIRC there is info on fulltones site and probably info on the forum if you search,..

It isn't hard at all.  It confused me at first, until i did it  a few times,...

smallbear also has a pic of his plastic dc power jacks that tell you what lugs are what,...

hope this helps,..

PS:i'd offer links but i am in ahurry

[jimlam]

Thanks formerMember1.

I'm a beginner with no electronics background except for highschool physics (which I've long forgotten) so I think I need a bit more help. I'm trying my best to do it myself though.

I suspect its cut the red and black wires halfway from the board to the battery snap. Solder the red wire from the battery snap end and the red wire from the board socket end to one of the terminals of the battery jack each. Then solder the black wires of both the battery snap and the board to the remaining terminal of the jack. Is that right? I'm looking at the picture of the jack from small bears and guessing thats what i should do.

Advice anyone?

Thanks. 

[formerMember1]

try this,...i think i am right,..

the +9v wire from the board goes to the top lug of the dc jack,  (smallbear has labled board plus)

the red battery clip wire goes to the middle height lug of the power jack (smallbear has labeled battery plus)

the bottom biggest lug of the powerjack is the negative/ground,..send a wire from that lug to the ring of the input jack,

the black battery wire should go to the ring of the input jack also,...

that is if you want the input jack to turn the power on and off, by inserting a cord, and that should also make the pedal use power jack when power adapter is plugged in, and battery if no adapter is plugged in,...

IIRC that is all right,...

PS:if you need more help, go to the "DIY Stompbox FAQ" on main page of  Aron's website,...

feel free to ask more questions,...

PSS:the above is for NPN pedals like your wah, a fuzzface or something that is PNP, will have the + and - reversed,...

[jimlam]

Been researching this topic abit from all the various sources. Think I know what to do already and am going out to buy the part.

Smallbear sells two versions of the jack. One boss style jack and the other a metal jack. I'm thinking of using the metal jack as it looks studier. The plastic one probably needs a bigger hole drilled and I'm not sure if I have a drill bit that big. If i use the metal one, do I need to isolate it from the wah shell? Smallbear says some applications need isolation. Is a wah one of them?

Cheers!

[formerMember1]

i always used the plastic ones, becuase the metal ones, touch the metal pedal and stuff happens,...i would go with the plastic ones,...

When soldering the dc jack, put an adaptor plug in it, so make sure pins stays straight,..also be quick with the iron, to not overheat, or might be intermittent,..

you are gonna need to drill the hole i think a 1/2",(max on my unibit) then you might need to file the hole oval like the jack,...use a round file from homedepot or somehting,..

buy a couple of them,...


not a  hard mod,...

[jimlam]

Ok. So I went out to buy boss style dc adaptor jack. Installed it. It works. Battery works when adaptor not used and if you take the battery out, the adaptor works.

But there is an unbearable hum! I tried a power filter. I put 100 ohm resistor between the dc jack +ve board lug and the red wire going to the board (i.e in series with the red wire). I also put a 220 microfarad cap across the +ve and -ve (soldered the +ve end after the resistor and the -ve end to the dc jack's -ve lug). Looks something like the diagram below.


                                             Red wire to battery
+ve lug-----------------------------------------------------------+

+ve lug         100ohm                Red wire to board     
-------------/\/\/\/\/\/\-------------------------------------------+
                                   |  +ve
                                   |                                   
dc jack                        __                                                    board
                                  __    220uf
                                   |
-ve lug                         |  -ve     Black wire to board and batt
-------------------------------------------------------------------+

Its slightly better but still humming badly. Tried wiring the jack a few ways(eg black batt wire to ring lug along with dc jack -ve lug wired to ring) but I'm still stumped.

Anyone can help? Anyone done it and have pictures to show how it should be correctly done?

Thanks.

[formerMember1]

try a power filter cap at about 100uF, or a 220uF.  I use a 100uF.

Or

Try moving your wah as far away as the power supply as possible, that should help some,..

Wah are notorious for hum with adaptors,...probably something to do with the inductor,...

Put the filter cap directly across power and ground. For positive ground pedal, put the cap - to power and + to ground. Reverse for negative ground circuit. (wah is negative circuit )