My amp is... ALIVE!

Sunk by Sirens

Sunk by Sirens

Mar 24, 2020
64
86
2,551
Underwater and drowning
#1
First post...

I am currently working with a Line 6 LD 300 Pro. Lately, and I can't tell exactly why, it has been turning on effects by itself, and more often than not, it's the filter envelope; usually it sounds like my amp just ate a thick pillow. The knob positions have no bearing on the changes my amp decides to make (i.e. what exactly it decides to eat).

I already had been having problems in which either the channel volume, overall volume, gain, and/or general EQ is inconsistent when switching between channels. I noticed when I finally got the compatible Line 6 shortboard. That was really going to help me use the effects it has available to their full extent; who plays an entire song with super heavy filter envelope or chorus? Anyway, it's hard to tell exactly what is changing because it's inconsistent. But I'll switch from A to B, and B isn't what it's saved as. I'll switch back to A, and A isn't what it's saved at, even though I was just playing it. I have to cycle between channels a couple times before it decides to load the channel properly. This happens using the shortboard and the amp's own buttons.

Lastly, it always, ALWAYS, plays show and tell with me when I first turn it on. The audible settings are always in some random, new selection, not corresponding to where the knobs are.

It's louder than the tiny Fender Rumble that came with my Squier Affinity P bass, so I'll keep using it. But it's harder to rely on it. I already decided I want/need a new amp, but that's gonna take a bit.

What exactly might be wrong? Can I fix it myself? Will I need to replace something?

At least it turns on and off when I tell it to.
 
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#4
Just an idea but have you checked to cord and the jack on the bass and amp. Temporary shorting may be sending the signal that turns on the effect. I alawyas try to think of the simple cheap solution first.
 
#5
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#6
Sunk by Sirens said:
I'll try to find the schematics online (bought the amp secondhand years ago).

I don't know have nor know how to use a scope or logic analyzer.

I know how to use a multimeter, and I plan to buy one as soon as the hardware store opens, pending the pandemic.
Click to expand...
I suggest that you look at the schematic, this is not at all an easy amp to troubleshoot because it's almost entirely DSP driven. Once the input signal is conditioned, just about all of the processing is handled digitally. that includes most of the pots and switches. This is why a logic analyzer and/or scope is important. You need to see what's happening and understand what's supposed to be happening so that you can identify where they don't agree.

You might get "lucky", but you will discover that it's anything but intuitive.
 
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#8
agedhorse said:
I suggest that you look at the schematic, this is not at all an easy amp to troubleshoot because it's almost entirely DSP driven. Once the input signal is conditioned, just about all of the processing is handled digitally. that includes most of the pots and switches. This is why a logic analyzer and/or scope is important. You need to see what's happening and understand what's supposed to be happening so that you can identify where they don't agree.

You might get "lucky", but you will discover that it's anything but intuitive.
Click to expand...
Since I plan on replacing this combo amp with a DIY fEARless cab and some-kind-of tube amp head, I don't see the benefit of buying a logic analyzer, but looking at these schematics, I understand the benefit of the tool.
 
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#9
Sunk by Sirens said:
Since I plan on replacing this combo amp with a DIY fEARless cab and some-kind-of tube amp head, I don't see the benefit of buying a logic analyzer, but looking at these schematics, I understand the benefit of the tool.
Click to expand...


A fEARful is typically DIY because Dave Green, A.K.A greenboy, made his fEARful plans publicly available for free. A Fearless is a newer Greenboy design. It is proprietary with plans available only to licensed builders, and thus, by definition cannot be DIY.

fEARful or Fearless, you will not regret using such a cabinet. I like the Mesa Prodigy tube head with a 12/6/1, but perhaps this is a discussion for a different thread?
 
#10
Jim Carr said:
A fEARful is typically DIY because Dave Green, A.K.A greenboy, made his fEARful plans publicly available for free. A Fearless is a newer Greenboy design. It is proprietary with plans available only to licensed builders, and thus, by definition cannot be DIY.

fEARful or Fearless, you will not regret using such a cabinet. I like the Mesa Prodigy tube head with a 12/6/1, but perhaps this is a discussion for a different thread?
Click to expand...
:wacky: Ah, typo, I meant fEARful. Yes, I actually know the difference. I specified DIY because I know there are a few authorized dealers who sell completed fEARful cabs and/or build kits. :thumbsup:

I'll try to dig around with the search function and figure out some of the nitty gritty, but if I can't find what I'm looking for, then yes I'll start a separate post for that discussion. At the very least, I'll post a "build-ography" that follows my process.

Even if I get a new amp/cab soon, I want to attempt fixing this Line 6 combo before selling it.
 
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#12
Do you or have you ever plugged in an FBV pedal to that amp? It goes into the RJ-45 jack on the front.

Shine a bright flashlight into the jack and look at it with as strong a magnifying glass as you can find. See if the wire "tines" have turned green, black, or have any kinda fuzz on them. If so, take it to a repair person and have them clean those tines in the jack and see if the amp still does things on its own. Those little metal tines can grow garbage on them and sometimes it pushes them together and shorts them, or causes some intermittent connections. It's a terrible design.

If not, continue on with testing equipment and the repair manual, or set it on fire - but if you set it on fire do it in an open field - there's lots of potentially fire-toxic junk in that box... ;-)

Side note: Those amps are Pre-Yamaha and the guys who used to write the manuals had a bit of a sense of humour. I'll always remember the manuals for the LD and HD amps listing the dials and switches. When they got to the power button, they had something like "Power Switch: The Amp sounds better with this set to "ON". - That was actually debatable.
 
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#13
frankie5string said:
Do you or have you ever plugged in an FBV pedal to that amp? It goes into the RJ-45 jack on the front.

Shine a bright flashlight into the jack and look at it with as strong a magnifying glass as you can find. See if the wire "tines" have turned green, black, or have any kinda fuzz on them. If so, take it to a repair person and have them clean those tines in the jack and see if the amp still does things on its own. Those little metal tines can grow garbage on them and sometimes it pushes them together and shorts them, or causes some intermittent connections. It's a terrible design.

If not, continue on with testing equipment and the repair manual, or set it on fire - but if you set it on fire do it in an open field - there's lots of potentially fire-toxic junk in that box... ;-)

Side note: Those amps are Pre-Yamaha and the guys who used to write the manuals had a bit of a sense of humour. I'll always remember the manuals for the LD and HD amps listing the dials and switches. When they got to the power button, they had something like "Power Switch: The Amp sounds better with this set to "ON". - That was actually debatable.
Click to expand...
Yes, as I said in OP, I only really started to notice the issue of the channels loading inconsistently whenever I tried out the FBV Shortboard.

I know all about how toxic electronics can be, particularly when combusted...

Gonna get together with my band's drummer at the practice space later today, and then I'll try all the easy troubleshooting tips.

I originally bought it for ~$250 off some local high school kid who ended up not liking bass or something crazy like that. Luckily I was able to make more than that playing all the gigs I have with it.
 
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#14
Sunk by Sirens said:
Yes, as I said in OP, I only really started to notice the issue of the channels loading inconsistently whenever I tried out the FBV Shortboard.
Click to expand...

Sorry, somehow I missed the bit about you actually using the floorboards <facepalm> ...

You can also damage the input by using the floorboard. It's got very little protection from static/shorting.

Good luck and let me know how you make out - I'm always surprised when someone mentions they're still using them - they really weren't very robust.
 
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#16
If you want to play around with the amp to try and fix it, go ahead. But if it were me I would probably just replace it and start your fEARful build. Your time would be better served with that. I don't know what your financial situation is, but that would be my plan. TB classified is full of used bass heads at all price points.
 
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#17
seamonkey said:
Schematic:
http://bee.mif.pg.gda.pl/ciasteczko...w_Down_LD150,_175,_300_Pro_Service_Manual.pdf

It's more complicated than a regular amp head.

Maybe check the front panel is clean, and some push button switch isn't half engaged from gunk around the button.

The service manual mentions a "Factory Reset" which when all else fails, it couldn't hurt to reset it.
Click to expand...

Thanks for posting that. I've always wondered how the Line6 amps do their thing but wasn't ever quite curious enough to actually go find a schematic.

OP: Agedhorse is right, you won't get anywhere on this amp without, at the very least, a digital oscilloscope. One thing you can try is a different FBV pedal to make sure yours isn't defective.
 
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#20
Sunk by Sirens said:
First post...

I am currently working with a Line 6 LD 300 Pro. Lately, and I can't tell exactly why, it has been turning on effects by itself, and more often than not, it's the filter envelope; usually it sounds like my amp just ate a thick pillow. The knob positions have no bearing on the changes my amp decides to make (i.e. what exactly it decides to eat).

I already had been having problems in which either the channel volume, overall volume, gain, and/or general EQ is inconsistent when switching between channels. I noticed when I finally got the compatible Line 6 shortboard. That was really going to help me use the effects it has available to their full extent; who plays an entire song with super heavy filter envelope or chorus? Anyway, it's hard to tell exactly what is changing because it's inconsistent. But I'll switch from A to B, and B isn't what it's saved as. I'll switch back to A, and A isn't what it's saved at, even though I was just playing it. I have to cycle between channels a couple times before it decides to load the channel properly. This happens using the shortboard and the amp's own buttons.

Lastly, it always, ALWAYS, plays show and tell with me when I first turn it on. The audible settings are always in some random, new selection, not corresponding to where the knobs are.

It's louder than the tiny Fender Rumble that came with my Squier Affinity P bass, so I'll keep using it. But it's harder to rely on it. I already decided I want/need a new amp, but that's gonna take a bit.

What exactly might be wrong? Can I fix it myself? Will I need to replace something?

At least it turns on and off when I tell it to.
Click to expand...

f2e1ab082e83ac27c667ae2d6102a3fe.jpg
 
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