Looking for an L2500 preamp 'parts list' if one so exists...

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Looking for an L2500 preamp 'parts list' if one so exists...

Postby Eastcoasteddie » Sat Jul 01, 2017 5:35 am

I'm looking for a part number list, and a vendor to putlrchase from, the correct replacement pets for an L2500 preamp.
Here is the back-story on my '97...

When I purchased it in '97, all I have been experienced with were EBMM Stingrays and other such active basses. When I got the L2500, I just didn't understand the preamp and when I realized that it didn't do what my Stingray did, I had it replaced. I was 22 years old, mind you, and have been playing bass for only 3 at the time (after playing guitar for 6 before that). I guess my main complaint was that with the bass control all the way up, it sounded like it was flat. I didn't realize that that was part of the deal...
So I had a basic 2-band preamp installed which did what I thought it should do. I had Rudy's Music in NYC install a Pensa preamp with bass boost and treble cut/boost. In Series, I keep the bass off 100%, and bring it up to about 50% in parallel, treble cut or boost to taste. However, I started to not like how the preamp sounds. There is a noticeable change in tone when engaged, like it scoops out the mids my about 10% and cleans up the "grit". I actually started using it in Passive more lately, but with the preamp off, I don't have a tone control...which is kind of why I want to bring the original preamp back...

So now 20 years later, I feel like I want to bring the OG preamp back to life. I have almost everything in a zip-lock bag that Rudy's returned to me after the replacement was done. I might be missing one or two things. The original 3-position A/P/Treble Boost switch actually found its way into the same L2500 as a 4th switch controlling inner/outer coils in coil tap mode. So I will need to get another OG switch for the A/P functions. Rudy's installed a standard 2-position A/P switch.
I have to check and see if I have both resistors that are in that part of the circuit; I know I have the one that is soldered to the yellow wire to the preamp, not sure about the one soldered to the pins of the switch.

The original bass and treble pots with caps I should still have...I just have to do an inventory.
Does an actual parts list exist?

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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Ken Baker » Sat Jul 01, 2017 7:39 am

Eastcoasteddie wrote:Does an actual parts list exist?


It sounds like you're looking for a parts list for the whole circuit, not just the preamp.

We don't have a true parts list. We do have a wiring diagram from which a parts list could be made.

Click the image for a PDF.
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This should be correct for your bass. Unless you have to replace the preamp board, you can ignore the note about R-11 and the v1.3 board.

You should be able to source the various components from Mouser and G&L. If you need a new bass pot, source from G&L. Switches are available from either Mouser or G&L, but getting the correct one would be easier form G&L.

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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Eastcoasteddie » Sat Jul 01, 2017 7:33 pm

Thanks Ken!
My preamp is v1.0 and I am not sure I have the 10meg resistor on the A/P switch, but I do have the 10k resistor that was moved on v1.3
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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Eastcoasteddie » Sun Jul 02, 2017 7:13 pm

Ken,
If I may ask...are there any tonal differences among all the different versions of the L-series preamps? Or are they just hardware related?
I see that G&L offers an entire wired preamp for $119...tempting...!!!
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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Ken Baker » Sun Jul 02, 2017 7:34 pm

Eastcoasteddie wrote:Ken,
If I may ask...are there any tonal differences among all the different versions of the L-series preamps? Or are they just hardware related?
I see that G&L offers an entire wired preamp for $119...tempting...!!!


There might be a slight difference in the treble bump, but probably not that you'd notice. The overall gain provided by the L Series preamps is very slight, but its bigger claim to fame is that it provides a low output impedance which allows for long cables without tone suck.

Replacing the whole assembly is quite temping. Figure the cost of parts to repair to original, not to mention labor, and that $120 gets more reasonable.

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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Eastcoasteddie » Sun Jul 02, 2017 7:51 pm

I have already sourced the switch and 10 meg resistor...will cost me about $6 or so. I have all the original pots with caps as well, though I installed a push/pull Bournes volume pot for part of the Series/coil tap wiring.
Mine came with Parallel/Coil tap from the factory...no Series. The 4th mini-toggle I added does Inner/Outer coils (as mentioned above), the push/pull volume brings in straight Series.
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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Eastcoasteddie » Mon Jul 03, 2017 7:40 am

Sorry...one more question...
The 10 meg resistor I need to get for the A/P switch...what wattage? The ones I found are 1/4 watt...
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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Ken Baker » Mon Jul 03, 2017 3:44 pm

Eastcoasteddie wrote:Sorry...one more question...
The 10 meg resistor I need to get for the A/P switch...what wattage? The ones I found are 1/4 watt...


1/4 watt is appropriate. Be sure to get 1% tolerance metal film. Also grab a short piece of spaghetti tubing or clear vinyl tubing to slip over it as an insulator.

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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Eastcoasteddie » Fri Jul 07, 2017 3:31 am

As it turns out, I am having a hell of a time finding a 10m metal film resistor...or even a carbon-film resistor locally...
I went to this pretty nice electronics store near me, and the only one he had was a Carbon Composite 10m...
Looks like if I need to get one, I have to buy a kit of about 1268 pieces and use the one... :!:

What with all the Radio Shack stores closing...the world will soon see their mistakes...!!!!

I may just need to break down and purchase 2 resistors online for $1.25 and pay $8.00 shipping...
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Re: Looking for an L2500 preamp 'parts list' if one so exist

Postby Ken Baker » Fri Jul 07, 2017 10:05 am

I don't know that Radio Shack would be the place. Try Mouser. Even Fry's, if you have one nearby.

10meg should be easy to find. If you can't find metal film, then go with the best tolerance (lowest numerically) you can get, maybe 5%.

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