jerry8jb
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Post by jerry8jb on Apr 22, 2009 10:37:38 GMT -5
Hi guys, One simple question for you guys, Electronic is not my cup of tea but I want to learn... HAve an recently purchase active guitar (used) that creates a medium hum up until I touch the string...opening the back cover I noticed that the battery black wire goes the ground terminal of the jack instead of the switch (ring)...the rest of the circuite grounds and everything seems normal to me when I compare with Internet wiring diagrams... Could that be my problem? Just looking foe advice prior heathing up the soldering pen... Thanks. Jerry
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Post by ChrisK on Apr 22, 2009 12:10:28 GMT -5
The battery black wire (-) going to the ring terminal on a stereo 1/4" jack simply is the practice of using a monophonic cable plug to function as the battery ON switch (the battery is out of circuit when the cable is not plugged in). You give little info regarding the guitar, pickups, and any active electronics therein. Such info would likely be helpful for those of us that can't see quite that far (away). It could be different things that are causing the hum.
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jerry8jb
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Post by jerry8jb on Apr 22, 2009 13:29:03 GMT -5
Hi,
The gear is a Yamaha Bass RBX1000, PJ configuration, 1 master volume, 1 blend pot, 1 bass, 1 treble. There is a PC board link to one of the bass/treble pot. (EQ side)
I was questionning myself on the fact that the battery wire is to the ground terminal of the panel jack, could cause the hum (since that it is normaly to the ring) or if this wiring condition is not related to the hum at all and will just impact the battery life.
Thanks Jerry
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Post by cynical1 on Apr 22, 2009 14:25:43 GMT -5
Just out of curiosity, if you pull the battery and go passive do you still get the hum?
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jerry8jb
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Post by jerry8jb on Apr 27, 2009 10:39:21 GMT -5
Hi,
Have no hum without battery since I have no output at all without it. Was it a tricky question?
I rewired the battery (-) to the switch terminal. The hum is still there but varies when using the pot which have the PC Board attache to it. Is there a way to isolate the PC board to determine if this is the culprit? Or can you guys give me some leads as what could cause this hum? As sonno as I touch the strings or bridge the hum disappears.
Thanks. Jerry
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Post by cynical1 on Apr 27, 2009 12:12:06 GMT -5
Is the ground intact from the bridge? If so, where does it join into the circuit?
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jerry8jb
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Post by jerry8jb on Apr 27, 2009 12:56:33 GMT -5
Yes it looks fine. It is joined to a pot's casing and all pots casing are joined together. The solder joint is fine. I will lift the bridge to see underneath it if for some reason the contact there is not okay.
The fact that the hum worsen when using the pot with the pc board, can the board be defective in some way? Is this board serve as the EQ Bass/Treble or as a small preamp, or both?
EMG state that the bridge ground is not required with their PU, is it a basic rule for any active PU or just proprietary to EMGs?
I had on one occasion that the ouput was weak with the bridge ground on with EMG nad okay once removed.
Thanks. Jerry
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jerry8jb
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Post by jerry8jb on Apr 28, 2009 10:50:48 GMT -5
Hi guys, I need your input, please.
The gear: Yamaha bass RBX1000, PJ configuration, single coil active, with what they call: Active Electronics, the RBX1000 includes a custom voiced active electronics system with 2-band boost or cut EQ, pickup pan control and master volume.
I suspect the PCB (which is attached to 1 of the tone pots) to be the problem and I want to isolate it to be certain. So basically I want to remove the tone circuit but I'm not sure if the PCB acts as a preamp or the EQ.
Here is my question: I have no problem taking the tone circuit out but I need to know where to connect the battery wires. The black is to the switch terminal of the jack. With the tone/pcb in, the battery red is going to a small connector on the pcb. Where should I hook it if I cancel the tone circuit? If I take the pcb out will the pick up still work? If I take the battery out too, are the pickup become passive?
Thanks.
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dugg
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Post by dugg on Apr 30, 2009 11:59:58 GMT -5
My daughter has that exact same bass, it's a great value. Also, it's dead quiet. I'm not nearly as knowledgable with things electric as Chris and Cynical1, but I do have over 35 years of modding guitars under my belt, and my instinct is leaning towards bad bridge grounding along with Cynical1. Look at it this way. The chances of a component on the circuit board loosening itself is far slimmer than the wire under the bridge. That being said, my daughers Yam actually did develop a bad connection on the board once. It was on the ribbon that connects the two boards. I'd still check the bridge first. Then look real closely at that ribbon connector because I think it's the second most likely place. It's definitely not the way the stereo jack is wired as a power switch, that is correct as Chris 'splained. If you were using some kind of wall wart as a power supply then you might have a pernt.....
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Post by ashcatlt on Apr 30, 2009 13:23:26 GMT -5
Seems to me the fact that the noise goes away (or is severely reduced) when you touch the strings or bridge must mean that the bridge ground is working fine. That's the whole pernt of that wire ain't it?
One might suspect a flaky connection there if it didn't change when touching the strings.
If you want not to use the PCB, you won't need the battery connected at all. You'll need to find a way to wire the pickup straight to the jack, like any other pickup. AFAIK, a lot of these pickups are just very light wound passive coils. I'd expect you'd get very little output, and it will probably be pretty thin. The noise will probably be quieter at a given amp volume level, because the whole output of the pickup will be lower.
Is this thing shielded properly?
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