G&L Tribute L-2000 preamp

[lintwind]

Hi Guys,
i have searched the previous topics before posting, but anyway:

i think my preamp chip is fried

it's a Trib L-2000, Korean made, 2004/5

plays superb and makes perfect sound, but when i turn Volume or Bass knobs there's an awful lot of crackling noise - that noise is much louder in passive mode, but somehow less in active/hi-EQ mode.

it's the same in passive mode with no battery.

the chip is soldered to PCB - so i think it would be much easier for me to replace the preamp instead of getting just the chip replaced and resoldered. (it's a LM4250CN, 8-pin hardwired to PCB)

so, the question is - can anyone recommend L-2000 preamp v2.0 seller in the UK/internet?

alternatively, can anyone suggest/confirm whether i can make it bypass the preamp altogether and make it completely passive? (i'm not that good with electronics, but can cut/solder wires and read simple schematics and i'm aware of the pickups going Y-split to passive out and to preamp off the same wires). I only play it passive anyway.

many thanks and sorry if there's already a topic for this.

many thanks,
lintwind

[4Mal]

Check the G&L forum at BadAssBassPlayers.com - I believe that in there somewhere you'll find links to the schematics.

If you're getting the crackling withthe pre disengaged - then I'm guessing you have somehting else going on. Loose wire, faulty ground kinda sorta thing ...

Cheap answer - get the scheamtic and follow it.

Expensiver answer ? Rip out the G&L stuff and inster and Audere 3zb with a pair of DP/DT on-on-on switches. Wire each pickup as single, outsode coil, inside coil and replace the standard controls with Vol, Stacked Mid on Blend, then stacked Treble on Bass.

I did my L2.5 that way and MFD's just love the Audere ... there's some clips over in the BABP G&L forum.

[dBerriff]

Before getting out the soldering iron, is it possible you just have noisy pots? If you are getting the noise in passive mode then the pre-amp most likely has nothing to do with it.

I think I might have read that the Tribute pots are not as good as the USA equivalent - but that is from memory.

Cure:

First aid: get some contact cleaner from Radio Shack or wherever and give the pot tracks a good squirt. This may be all you need to do. Pots sometimes get noisy if they have not been used much.

Long-term: replace the pots - the G&L on-line store sells the correct model.

[DavePlaysBass]

You say it makes a perfect sound until you turn the pots. This does not sound like a preamp issue to me. But keep in mind that the G&L preamp has a way of dying that still hurts you in passive. The opamp chip is always in the circuit even when in passive and there are failures where that chip dies and still hurts you in passive mode. The easiest way to diagnosie the preamp is to find the schematic and lift the wire that comes off the volume pot and goes to the preamp input. Basically take the preamp input point out of the path. But I agree with the other posts suggesting pots.

[lintwind]

Many thanks for your replies guys!
I know i should have investigated the pots first, but i was just too concerned with the nature of the crackle - it sounded far too digital to my ears (not like the "evil sweep" of preamp discharging itself, i know that one), but of really high frequency crackle. I just wasn't sure if it could have been the pots.

Anyway, i should try some contact cleaning spray first.

many thanks,
lintwind