Bartolini MK1 Help Please.

[pain995]

I have an older version Ibanez SR500 that began having issues where it would work for a short amount of time then the sound would just die. An old acquaintance took a look and said the preamp had failed and needed to be replaced. I decided to go with a tone monster preamp for ease of installation along with positive reviews. I installed it and no sound just a light humming. The vendor was kind enough to send a replacement just in case it was bad. Got a replacement and the same thing (no sound just humming). The vendor tested the preamp that I sent back and it tested ok. So I did an Ohm reading on both the neck and bridge pickups and I get no reading. Am I missing something could I have both pickups go bad? I never had a pickup ever fail let alone two at once? Anyone have something like this happen to them? I keep thinking I'm doing something wrong in troubleshooting? If they did go bad to purchase replacement Bartolini pickups and preamp I'm almost at the price of a used SR500.

 

[dwizum]

Zero could just indicate a short somewhere outside of the pickup. How exactly were you testing? Have you checked the wiring over to make sure the signal isn't shorting to ground anywhere?

 

[pain995]

I actually pulled the pickups completley out and set meter at 2000 ohms for testing

 

[dwizum]

No visible damage to the wiring - such as where the wires join the pickup body? Nothing touching anything it shouldn't be? Old bart pickups like to get shorts right where the signal joins the pickup body, the wire frays and touches the grounding on the back of the pickup.

I think it's safe to say that it would be incredibly unusual for both pickups to fail short at exactly the same time, out of the blue.

Can you put the pickups in the bass and connect them (one at a time) directly to the output jack? No preamp, no controls, no anything - just the ground and signal from the pickup connected to the tip and ring on the jack?

 

[ex-tension]

So I did an Ohm reading on both the neck and bridge pickups and I get no reading...I keep thinking I'm doing something wrong in troubleshooting?

I actually pulled the pickups completley out and set meter at 2000 ohms for testing

What do you mean by "no reading", what does your meter show?
MK1 pickups measure around 7-8 kohms so, you should put your meter on a higher measuring range (like 20kohm).

 

[pain995]

OK I feel like an idiot right now looking closer there is a color lead coming internally from the back of the pickup. The black lead is on a metal plate glued onto foam that is glued to the pickup and does not feed internally into the pickup. So, of course, I would not get a reading because there is not a completed circuit (see image attached). I guess I'm confused if there is only one lead going into the pickup...how does it complete a circuit?

 

[rojo412]

They use a coaxial wire. If you strip back the red, there should be a white wire in there, surrounded by plain, bare wires. Twist the plain wires together into a - lead (surround most of it with heat shrink, if you have it), then strip back the white a bit to reveal the + lead.

 

[pain995]

I can't wait to go home and whack myself upside the head when I see its a coaxial cable. I just want to thank everyone for the support you have given.

 

[pain995]

They use a coaxial wire. If you strip back the red, there should be a white wire in there, surrounded by plain, bare wires. Twist the plain wires together into a - lead (surround most of it with heat shrink, if you have it), then strip back the white a bit to reveal the + lead.
View attachment 3933647

So the black wire that is soldered to the metal plate would that get soldered to the back of one of the pots as a ground?

 

[rojo412]

Yep!

 

[dwizum]

Glad the problem is solved. Just FYI it's not always typical to use the pots in an active preamp as grounds (as is commonly done in a passive bass) - might want to run that pickup shield wire to another ground point (i.e. the jack ring) unless your preamp already has the pots grounded.

 

[rojo412]

I like using these solder lug washers whenever possible:

When doing a wiring setup, I'll typically put these under EQ pots, run a chain of them, making sure they all connect to the bridge ground. It does a great job grounding the pots and not requiring any solder connection to the case. It also helps connect the shielding (paint, in my case) to the ground properly and securely.

FWIW, I haven't really run into issues soldering the grounds to casings, but definitely feel this a more efficient and elegant way.
And you can also wire the "anti-spin" washers with leads that can connect to ground, if you don't want to buy these.

 

[pain995]

Glad the problem is solved. Just FYI it's not always typical to use the pots in an active preamp as grounds (as is commonly done in a passive bass) - might want to run that pickup shield wire to another ground point (i.e. the jack ring) unless your preamp already has the pots grounded.

han

I like using these solder lug washers whenever possible:
View attachment 3934917
When doing a wiring setup, I'll typically put these under EQ pots, run a chain of them, making sure they all connect to the bridge ground. It does a great job grounding the pots and not requiring any solder connection to the case. It also helps connect the shielding (paint, in my case) to the ground properly and securely.

FWIW, I haven't really run into issues soldering the grounds to casings, but definitely feel this a more efficient and elegant way.
And you can also wire the "anti-spin" washers with leads that can connect to ground, if you don't want to buy these.

Great idea!! Thank you for sharing!