NTMB Wiring Issues

[Mr_Pleb_Mgoo]

Hi Guys

Sorry if this sounds forward, started wiring this thing at 8:30pm and it's now 2AM.

I have an Ibanez SR900FM that the pre-amp died in, so got an NTMB 5.2 setup (3band, push-pull active/passive, push-pull mid switch). SR900 comes with Bart Mk1 pickups.

The kit came pre-wired so all I had to do was wire in the battery, pickups and the input jack as the Ibanez use the barrel jacks.

I can't for the life of me get any sound out of the thing, this is how it's currently wired:

Middle Volume Lug to Output Jack Tip
Pre-Amp Module (Black) Ground to Output Jack Sleeve
Battery Negative to Output Jack Ring
Bridge Pickup Positive to Blend Lower Middle Lug
Bridge Pickup Ground to Output Jack Sleeve
Neck Pickup Positive to Blend Upper Middle Lug
Neck Pickup Ground to Output Jack Sleeve
Volume Ground Lug to Output Jack Sleeve
Bridge Ground to Output Jack Sleeve

I've also tried grounding the Pickups directly to the Volume pot and Blend pots with no change. I figured electronics are electronics and anything pointing to a ground symbol should all share one grounding point but now I'm not so sure...

I am able to get plenty of "Bzzzz" with this setup, which mutes upon touching strings, guess that means the bridge ground isn't working properly? I've tested another bass with the cable and amp setup and it works perfectly (Warwick Corvette RockBass).

I'm totally stumped with this one and very tired / sore / headachey can anyone help me please?

 

[ex-tension]

Do you have the Bartolini wiring diagram? And you did follow it (or double checked the wiring)?

Does it work on passive mode?

Your battery is good?

NTMB has two modules and each has it's own black (ground) wire. Are both of them connected to jack sleeve?

The preamp input is yellow wire (with ferrite beads). Is it connected to the blend pot on the correct lug? The blend pot has two jumper wires?

Preamp output is the green wire. Is it connected to the volume pot?

Any pot lug is touching the cavity walls?

 

[Mr_Pleb_Mgoo]

Do you have the Bartolini wiring diagram? And you did follow it (or double checked the wiring)?

Does it work on passive mode?

Your battery is good?

NTMB has two modules and each has it's own black (ground) wire. Are both of them connected to jack sleeve?

The preamp input is yellow wire (with ferrite beads). Is it connected to the blend pot on the correct lug? The blend pot has two jumper wires?

Preamp output is the green wire. Is it connected to the volume pot?

Any pot lug is touching the cavity walls?

I followed the wiring diagram to the best of my ability - as far as I can tell yes I followed it properly heh.

Doesn't work in passive mode (no change)

Battery is good (rechargable, get 9v + through tip or ring + sleeve)

Smaller module's ground was pre-wired to the volume pot, larger module's ground is wired to the output jack sleeve.

Preamp input (yellow wire) connects to a lug on the Volume pot, then another yellow wire runs from a lug next to it to the correct Blend pot lug - this was pre-wired and I did notice it's different to the diagram.

Preamp output is connected to the Volume lug opposite the Input (Yellow wire) lug.

The Pots themselves are clear of the cavity walls but the pre-wired 'bare' ground-loop wiring is touching the walls (quite a tight fit in there!)



I think the wiring for the Yellow wire is different because the Bartolini diagram doesn't account for having a Push-Pull Active/Passive switch.

 

[Mr_Pleb_Mgoo]

Here is a wiring diagram just of the wiring I've done myself + how the volume pot is wired (active/passive switch)

Note: there's one ground missing in that diagram, it runs from the Treble pot to the sleeve - all pots are daisy-chain grounded to the treble pot.

 

[ex-tension]

I followed the wiring diagram to the best of my ability - as far as I can tell yes I followed it properly heh.

Doesn't work in passive mode (no change)

Battery is good (rechargable, get 9v + through tip or ring + sleeve)

Smaller module's ground was pre-wired to the volume pot, larger module's ground is wired to the output jack sleeve.

Preamp input (yellow wire) connects to a lug on the Volume pot, then another yellow wire runs from a lug next to it to the correct Blend pot lug - this was pre-wired and I did notice it's different to the diagram.

Preamp output is connected to the Volume lug opposite the Input (Yellow wire) lug.

The Pots themselves are clear of the cavity walls but the pre-wired 'bare' ground-loop wiring is touching the walls (quite a tight fit in there!)

I think the wiring for the Yellow wire is different because the Bartolini diagram doesn't account for having a Push-Pull Active/Passive switch.

If it doesn't work on passive mode the problem should be on the blend pot or the A/P switch.

A/P push/pull switch looks like OK. You can check it here:
Invalid Link Removed

Bare grounding wire of the pots touching the cavity walls is not a problem. Is any lug of the output jack clear of the walls as well? And are you sure of the correct T-R-S connections on the jack? It's easy to mix them on a barrel type jack.

Here is a wiring diagram just of the wiring I've done myself + how the volume pot is wired (active/passive switch)

Note: there's one ground missing in that diagram, it runs from the Treble pot to the sleeve - all pots are daisy-chain grounded to the treble pot.

The blend pot has the jumpers (bridges)? There should be a bridge between 'lower left lug' and 'upper right lug'. And another bridge between 'lower right lug' and 'upper left lug'. Also the upper left is grounded. But it should work without the ground as well.

The missing things on your diagram are:
- the ground connection of the volume pot
- blend pot bridges
- blend pot ground connection

If you cannot solve it, try to connect the pickups one by one to the output jack to see they do make sound or not.

 

[Mr_Pleb_Mgoo]

Thanks for the assistance mate I appreciate it

The blend-pot does have the jumpers as you've mentioned, the Blend Pot Ground links back to the Volume pot.

I am fairly confident I have the pinout of the jack correct, I had an identical model that I installed in an active Corvette Rockbass with no issue. The output jack lugs are all clear of the cavity wall also.

I will need to double check the volume pot ground, if that's OK then I will test the pickups as you've mentioned.

 

[Mr_Pleb_Mgoo]

Ok so gave it the once over today and have fixed it!

My pickup wiring wasn't as it seemed, the "2 wires" from the Bartolini MK1's was actually 3 - the black one is linked back to a separate grounding plate the pickup sits on, the thick red / green wire coming from each pickup actually had a white wire inside it that was surrounded / disguised by shielding. Once I realised this, I soldered the white wire to the points the instructions directed me to and then soldered the shielding to the adjacent ground lugs on the blend pot. I then had some issues where the blend pot was muting the neck pickup instead of blending but this was just due to some bad soldering I did.

Haven't tested the sound out yet (it's midnight ) but even just the odd pluck to test the signal sounded great, a little noisy when the pre-set gain is cranked up (not much headroom with the Mk1's on a single 9v either) but not as bad as the stock SR900 pre-amp

If I hadn't tested the pickups directly I would have never figured this out so thank you ex-tension for your help .

 

[ex-tension]

AH! The grounding plates!
So, I suppose it wasn't you who removed the pickup cables from the stock MK1 preamp. Otherwise you would have known about the shielded pickup cables.
Anyway, it's nice to see that you figured it out. And not at all

You can set the preamp gain to have equal output level on active and passive mode (if you dont want volume differences when you change from active to passive).

Now, post it here:
http://www.talkbass.com/forum/f38/guts-glory-show-your-bass-guts-706116/

 

[Mr_Pleb_Mgoo]

Hehe I actually did cut the pre-amp out myself, but the stock Ibanez wiring is shocking - they leave enough spare wire to pull the whole thing out almost a meter from the guitar

I just cut the cables and figured the wiring diagram with the new pre-amp would direct me, didn't pay enough attention to the pickup cables hehe

I'll post a guts picture tonight

 

[larrygs]

Exactly the same problem I'm having and same mistake, almost sure this is my solution, thanks ex-tension and Mr_Pleb_Mgoo for this, don't know why I did not saw this post on all the search I did on the forum.