Ibanez MDB1 no sound

[The BATT man]

Hello, long time stalker-first time poster. Please excuse my forum etiquette, I am old and new to this. I have an Ibanez MDB1 that was working fine, then the other day I get it out and NO sound, check the battery first 9.4 volts, cable good, check jack switch for batt-it is working, check DC resistance from pups-good, check continuity at the pot, from L1, 2 & 3 all wires have continuity from point to point. This bass has a "pre set" EQ board, and only 1 vol, that has a white wire from L1 to PC, and a black wire from L3 to PC, on the same board it has a 3 wire plug, red (9v). white out to jack, and black to (swt-) from jack. ALL of this seems to be working, but no sound. Does this mean that EQ board went out? I am assuming that since these are the "SRX" passive pickups, can i simply wire it passive direct to vol knob? I apologize if this is in the wrong thread.
Thank you for any and all help!

 

[ardgedee]

This will sound like a stupid suggestion, but try a different battery first. Sometimes a 9v tests fine but won't work properly because it doesn't fit the compartment, or doesn't have good contact with the terminal, or some other reason.

 

[KevInDaBassment]

EDIT: Just saw it's a 1-knob, I read SRX and thought it was the same wiring diagram. Yeah, I'd go all passive or perhaps do some drilling. Board or wiring could still be the problem though.

Might also want to check and make sure something isn't grounding out unintentionally. Exposed wires, solder joints on the EQ board, or anything else coming in contact that shouldn't. On most Ibanez basses they spray the cavities with shielding paint, so that or the shielding on the backplate could be making contact.

Try it with the backplate off and see if you get anything. If all is good, then you may have something shorting to ground in the electronics with it closed. I'll also say it's not unheard of for one of those boards to stop working. I had one do the exact same thing and a replacement board did the trick. Passive wiring for those pickups would work fine, but there's also plenty of 4-knob preamps out there that will sound great with them.

 

[The BATT man]

EDIT: Just saw it's a 1-knob, I read SRX and thought it was the same wiring diagram. Yeah, I'd go all passive or perhaps do some drilling. Board or wiring could still be the problem though.

Might also want to check and make sure something isn't grounding out unintentionally. Exposed wires, solder joints on the EQ board, or anything else coming in contact that shouldn't. On most Ibanez basses they spray the cavities with shielding paint, so that or the shielding on the backplate could be making contact.

Try it with the backplate off and see if you get anything. If all is good, then you may have something shorting to ground in the electronics with it closed. I'll also say it's not unheard of for one of those boards to stop working. I had one do the exact same thing and a replacement board did the trick. Passive wiring for those pickups would work fine, but there's also plenty of 4-knob preamps out there that will sound great with them.

Thank you for the response, yes all the checking I did was with the cavity cover off, the "EQ" board has a piece of felt covering the solder joints, and I did move the PC board away from the "black" grounding paint just to eliminate any chance of grounding out. The MDB1 is the Mike Dantonio signature, its basically a SRX 700 but only has 1 vol pot and that's it.

 

[The BATT man]

This will sound like a stupid suggestion, but try a different battery first. Sometimes a 9v tests fine but won't work properly because it doesn't fit the compartment, or doesn't have good contact with the terminal, or some other reason.

I will try that tonight. I have a bit more testing I am going to try. Thank you for the response

 

[The BATT man]

One thing i forgot to mention that may be of help, the black and white wires from the vol pot go to the PC (seem to be input signal) and the other white wire on the the 3 wire plug (PC) seems to be the out put wire to jack-there is no continuity from white or black wire input to the white output,(with or without cable plugged in) that is why I believe its the board??

 

[rojo412]

I've never seen one of these before, would definitely be curious to see a pic of the internals.

If it's me, I'd be trying to run the volume direct to the jack, just to make sure that it's functioning as it should. Temporarily, of course.
I'd also likely try to run the pickup signal directly to the jack. Just to make sure the pickups are sending signal as well.

With those possibilities eliminated as problems, then yeah, I'd probably be concerned with the board itself.

 

[murphy]

I ripped the preamp out of my 5-string Soundgear SR and turned it all. Passive sounded way better

 

[KeepItMoving]

So, you've most likely done this already but juuuust to be sure as it's not mentioned in the original post — you've tried the bass through a couple of different amplifiers to make sure the problem isn't downstream?

 

[Crater]

There will usually not be any measurable continuity (ohms) from the input of the output of a preamp circuit. Coupling capacitors on the input and output block the DC bias and power rails from the audio input and output.

 

[The BATT man]

Thank you for the help! I got it fixed. turns out a pot can test good with a multimeter but not pass sound? I worked backwards from direct to jack from pups, I would have sound after one fix then it went away, left the pot out of the cavity and thumped on with finger, and that was it. I have never had a pot do this before...live and learn!

 

[The BATT man]

I've never seen one of these before, would definitely be curious to see a pic of the internals.

If it's me, I'd be trying to run the volume direct to the jack, just to make sure that it's functioning as it should. Temporarily, of course.
I'd also likely try to run the pickup signal directly to the jack. Just to make sure the pickups are sending signal as well.

With those possibilities eliminated as problems, then yeah, I'd probably be concerned with the board itself.

Sorry, I already closed her up. I have a drawing for the SRX, drawing #WB020008 and it is basically the same wiring (EQB2DX) w/o bass boost/cut, treble boost/cut or balance. L2 hot from vol pot to IN of EQ & L3 (-) from vol pot in to EQ, then white OUT from EQ to jack, then of course the EQ has red & black from battery, and that's pretty much it.