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Distorted signal from SG Ibanez SR400 FL

BooDoggie

BooDoggie

Typical Dumb-ass with a degree
Mar 29, 2014
575
972
www.spsclub.org
#1
Hey all... i recently picked up a 1998 Soundgear Ibanez SR400 FL fretless mainly just to learn to play on, but there is a lot of distortion coming from the output into both my amp and direct to my DAW interface. If I turn it down to almost off the distortion is much less and even hard to hear at all. This is a total disappointment. I have checked and verified that the problem is in the bass because all of my other instruments sound fine and there is no clipping occurring on the input to the DAW or the amp. I have checked the wiring diagram and it appears to be as it should be, and I put in a new Duracell battery and cleaned the pots with CRC.

I have been searching for a replacement pc board with no luck. I only payed $150.00 for the bass and I don't want to spend a lot of money on it. Could the problem be with the pickups? Is it possible to rewire it and bypass the onboard preamp and go direct from the pickups to the output with just a volume and tone control? I have a lot of experience with electronics, so I have no problem diving in and making changes
 
#2
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This is the diagram from Ibanez. I do have one additional wire that goes from the GND pin to the base of the bridge.
 
#5
Killed_by_Death said:
Then you should know that a great way to troubleshoot is through the process of elimination.
bypass the pre-amp & then you'll know if it's the culprit
Click to expand...
I guess that hooking the output from one of the pickups directly to the jack should work for troubleshooting purposes. I see no other way to bypass the preamp. I have read that this model is known for issues with the preamp and possibly with the pickups as well?
 
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#7
Bad or corroded jack? I've had this happen before. I ended plugging and unplugging a cable in and out of the jack 10 or so times and it eventually solved the problem. Also make sure the cable is seated all the way into the jack. I've also had the same problem from a stiff jack not wanting to seat the 1/4" end fully. Just a few ideas to try out. You might luck out and have an easy fix? Good luck!
 
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#8
I removed the pc board from the bass this morning. I thoroughly cleaned all of the pots with CRC and even pulled the ic chip out and cleaned the contacts on it as well. I lubricated all of the pots and I cleaned the barrel jack with CRC and plugged and unplugged a cable about 50 times then sprayed it out again with CRC. I put the pc board back in and re-soldered every wire connection. I even re-soldered the wires at both ends of the battery connector and reinforced the battery end with a layer of epoxy. So I guess the board is shot. If I turn the bass and the mids all the way down I can play it without distortion. But if I play hard it still farts out like a clipped input signal would sound. I can't hear any difference when I turn the treble knob, but that might just be my hearing... :)

So I guess the Soundgear SR 400 is not so good... Oh well, I bought it because I wanted to play on a fretless and see if I liked it. (Which I do.) I ordered a sanding block to resurface the fretboard. The strings on it are fairly new flatwounds in what feels like a light gauge or low tension, but I'm not sure about that as I have no real experience with a fretless bass. That and I don't have a micrometer to measure them. I guess I'll keep it for awhile and just play softly or change it to passive and see if that works. Then I'll try to save up to get a better bass. $150.00 gamble... What the heck.
 
#10
Killed_by_Death said:
You don't NEED to have a pre-amp at all. Remove it or bypass it.

Actually, after looking at the drawing, you would need to remove it & use different pots.
You could make it completely passive with:

Volume neck
Volume bridge
bass cut
treble cut
(either a pickup selector switch OR a series/parallel switch)
Click to expand...

If you know of a schematic diagram and a list of parts to use I can do the work myself. Unfortunately, I don't know the difference between a 50K Ohm pot and a 500k Ohm pot except that they are different values that make a big difference in what comes out. The bass has 5 knobs so I guess that is where the 4 pots and 1 switch come in.
 
#14
Watchootognbout said:
Have you tried lowering the pickups?
Click to expand...
I tried to, but the j pup would not go any lower. I found a chunk of wood underneath the j bridge pup that had been there since the bass was made that was stopping it from going any lower on one end. the retainer/adjustment screw heads are so badly stripped that it was hard to get them out and back in. I do think it helped some, but I'm going to need new screws to do it right. This is turning into a project more than I wanted it to be.
 
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