Bad preamp?

[SOB H.R.MC]

My 3B is giving me grief .The the output seems to fade in and out then gets really muddy.I have changed the 9v twice(yes, they were brand new) and figured it was my amp head.Anyone had the same issues?

[Spivonious]

preamp tubes?

[SOB H.R.MC]

On-board . It's inside of the bass

[SOB H.R.MC]

I picked up a 5 string by another manufactuer and played it for an hour and a half and I know the amp is fine(the first 45 min. I was expecting the symptoms to start ,the last 45 min. I was kinda hoping they would)

[Spivonious]

Interesting. Can you test the battery with a multimeter to make sure you're getting 9V? The symptoms definitely sound like a bad battery...it's possible you just had two bad ones in a row. Also, I'd check the wiring to make sure everything is solid. It's possible one of the solder joints has gone bad.

I highly doubt it's the actual preamp circuit.

[SOB H.R.MC]

I will test the batterys with my craftsman multimeter tonite.Do you know what the high/low limit is for a 9 volt?

[amimbari]

that's weird I never had a pre go bad except for the pot soldered on the board and it starts by getting scratchy when you turn it..

I know mine all do the same thing, but not till the battery gets to around 6 or so volts, then the pre goes whacky before it dies totally.
there's also bad pots or switch, but they usually indicate that by the scratchiness that you can hear with the turning of the knobs.

Chowederboots has a spare preamp still IIRC. if it is really going bad you can PM him and snag it off him for cheap...

[SOB H.R.MC]

New battery always fixed these same symptoms before.I hope it's a easy fix ,the 5 string is a P.O.S.

[amimbari]

not that this may have anything to do with your issue SOB, but the jack contacts have to make/break for battery voltage, and if that contact is dirty/corroded whatever, you may not be getting 100% voltage from the battery into the preamp...plug a cord in when you change the battery and read the voltage AT the pre not just from the battery.

just another thought :idea:

[Chowderboots]

If you find it's the preamp, like amimbari said, I've got one kicking around that I'm not going to use in anything...

[MetalMedal II]

not that this may have anything to do with your issue SOB, but the jack contacts have to make/break for battery voltage, and if that contact is dirty/corroded whatever, you may not be getting 100% voltage from the battery into the preamp...plug a cord in when you change the battery and read the voltage AT the pre not just from the battery.

just another thought :idea:

If it's the original jack, it could very well be the culprit. They were made of a square plastic housing that easily disintegrates with time and can short out the output. Change it for a switchcraft stereo jack.

[amimbari]

If it's the original jack, it could very well be the culprit. They were made of a square plastic housing that easily disintegrates with time and can short out the output. Change it for a switchcraft stereo jack.

thanks MM, it takes a fresh mind to think up something different

and yes he means this type of jack, and I have replaced a couple myself, but none on the ones I have.


.

[Chowderboots]

Oh yeah those jacks...I don't like the 3-way toggle switches with the plastic housing, either. They work, but they tend to feel a little shoddy.

[JACKSONFREAK]

Could also be the battery terminals on the clip or even the wires at either end.
from the pic the terminals look to be out of round and could be loose. casuing similar symptoms as a bad jack or bad battery.
Gil

[SOB H.R.MC]

I have not had the time to tear into it (5 kids between me and the ol'lady).I'll definatly know by monday if its the output jack or the battery clip .Thanks everyone for your time.