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HELP: Flextone III XL Only Left Ch. Working
by the_philth on 2009-12-23 12:25:29.7980

I'm sure this can apply to most Line 6 stereo amps, but I'll only refer to my Flextone here, as I'm sure someone with a stereo amp may have had or will have this problem in the future --- ergo, this thread will not only help ME and MY situation, but will hopefully help others!

Okay so, I loaned my combo to a friend (so he doesn't play guitar through the P.A. --- which he always does) so he can play a gig in Vegas. When I get it back a few weeks later, I'm hearing sound from the Left speaker only. The only change that was made --- I performed a Factory Reset and auditioned each setting with the Floorboard before I dropped it off at my friends studio.

I'm hoping that it's something like a Power IC or a Fuse that I can swap out myself. A bit of heads-up; I have a feeling the Perp' shoved his Boss ME-70 in front of the amp as he usually does with the house P.A. Maybe that helps with troubleshooting(?). There's also no buzzing/hissing or humming coming out of the Right speaker whatsoever; it's completely silent.

Thanks in advance to you guys for your suggestions!


Re: HELP: Flextone III XL Only Left Ch. Working
by Nick_Mattocks on 2009-12-28 06:33:07.7540

I hate to say this, but don't lend gear that you value to anyone   I've been caught myself more than once by someone else mis-using kit I've loaned them in full working order and breaking it, scratching guitars etc..., and I've seen other people suffer the same fate.  It has to be said that it's more acquaintances with whom I've been friendly that have acted this way rather than long term friends.  There are a lot of freeloaders around unfortunately.  they rarely accept any liability, their wallets tend to stay firmly shut and it's 100% impossible to prove sometimes even when you're in the room when the problem occurs.   It's a hard lesson to learn, even though I'll do my best to help anyone out, however nowadays, no-one but me gets to use my good amps and my good guitars (even though it goes against the grain to appear to be so tight-a*sed about such stuff) and I would not expect anyone to loan me their gear either as I'd hate for anything to happen to it whilst in my possession.

Anyhow as to the cause of your amp's problem.  It sounds as if either the speaker on the non functioning side is damaged - and you can easily check this by swapping the spade connectors from the speaker that is working onto the apparently non-working one (ensure you remember which wires are attached to which terminals and tape up any temporarily disconnected wires so they don't short on each other or anything else), or the power amp on that side has a problem.  The second scenario is more likely IMO.  I'm not familiar with the Flextone III XL but if it has an extension speaker socket on each output, I wonder if your friend has attached an extension speaker cabinet to the affected side's output or perhaps the PA guy has attached a DI box of some sort to that output, caused the speaker load impedance load to drop below 8 ohms (assuming the Flextone III XL is set for an 8 ohm output like the Spider amps are) and popped a power transistor protection fuse (if there is one - there should be but I wouldn't guarantee it) or the power amp module itself.

Shoving an FX board between the guitar and amp input should not have caused any problems.

You really need to get the amp checked out and repaired by a qualified technician at a Line 6 authorised repair facility it would seem, and then depending on how you feel about it and how much you value your friendship, try to get your friend to cough up something towards the cost of repair or rental costs for the privilege of having borrowed your gear to do a paid gig (I assume he did get paid) - good luck on that one.

I hope it is something simple (and inexpensive).  Good luck.


RE: HELP: Flextone III XL Only Left Ch. Working
by AParedes on 2010-01-08 10:04:42.3600

This information is correct. Please take your unit to your nearest repair center for diagnosis/repair:

GPS Electronics

13045 Tom White Way Suite I

Norwalk, California 90650

562-802-0840 (phone)

Please be sure to award Helpful and/or Correct points to community members who respond with helpful or correct answers!

Re: HELP: Flextone III XL Only Left Ch. Working
by the_philth on 2011-07-21 12:02:54.7330

Okay, this is a very late update, but definitely not insignificant!

NickMattocks: I'm part of the (I've learned this about myself throughout the years) type of musician that likes to help out other fellow musicians in need, hence my update here; meaning, I have excellent gear, vintage and modern alike. If I have a friend who's in need and I have the means to help him out, then you can bet I'm gonna do whatever I can to help out! Since he had a wedding gig in Vegas, instead of loaning him my Hughes & Kettner TriAmp half stack --- which is a pain in the butt to lug around, or having him go direct into the PA, I programmed my Flextone for the type of tones he was gonna be working with, and voila... he was set!

Now, I haven't used my Flextone in over a year because I've been playing bass or gigging with my H&K guitar rig, but a few "Blues Night" gigs have been popping up lately and I thought it was time to pull out the leaf blower and blow the two-inch thick skin of dirt off my old girl and open her up to start troubleshooting. I checked both Celestion’s against another amp and those sounded fine – no crackling whatsoever --- next up was to replace the output IC’s. Check this out - I also came across the following Service Bulletin for the pre-2000 Flextone's…

Indications: Amplifier cuts out after a few minutes of high volume use.

Part Numbers affected: 30-51-6063 (output amp heat sink) and 12-30-3886 (output device)

Tools/Supplies Required: #2 Phillips screwdriver, heat sink compound

Repair Procedure

  • Remove the (4) chassis screws on the top of the amplifier.
  • Remove the (2) handle screws.
  • Disconnect the speaker leads, remarking the location the leads
  • Remove the (2) screws on the bottom of the chassis
  • Remove the nuts on the 1/4" phone and the effects send and return jacks
  • Slowly pull the bottom plate of the chassis off and when it pulls away, reach in and pull the ribbon connector from the main board.
  • Look at the amplifier IC and see if the screw holding the output IC to the heat sink is in straight. If it is you can loosen the screws on the bottom of the heat sink and tighten the screw to 10-12 in lbs. If the screw is not straight, you may need to replace the heat sink. Also be sure that there is sufficient heat sink compound on the back of the IC. It should cover the back but not ooze out when the IC is secured tightly.
  • Reassemble the unit

I figured if I was gonna be deep in and pulling out the main board and heat pasting both IC’s, I might as well replace ‘em both just to be on the safe side. Well, turns out, as I stated in my initial post, I was right (I sure do love patting myself on the back when I deserve it). I replaced both IC’s and I was back in business. I’ve seen forum posts using keywords such as Line 6 Flextone... “left channel noise” or “farting sounds” and “cuts out after 5 minutes” amongst others; so I thought, if there was a Service Bulletin written, then I’m sure my post will help so many people with their combo’s.

This project took me about five hours in total --- but keep in mind, there were laundry loads, smoke breaks, phone calls and visits in between. But it’s a fairly simple job for the experienced tweaker and a not-so-simple job for the soldering rookie! I would imagine this type of job would be in the neighborhood of $75-$120 for a certified tech to replace both amps if you can’t do it yourself; but it’s a super simple procedure. The IC amps I ordered through Digi-Key were $14.60 for the pair and the part# is LM3886TF-ND. I also used some Heat Sink Compound that you can get from Radio-Hack. You don’t need to spread it on thick --- all you need is a razorblade or something equivalent, and smooth it on like if you’re repairing a hole in drywall or leveling some concrete. Wipe off the edges and BOO-YA!

Hope this helps anyone out there with a pre-May 2000 Flextone II.

Musicians helping musicians baby! That’s what it’s all about! Hope I helped!

Thanks for the reply Nick and Andy!


Re: HELP: Flextone III XL Only Left Ch. Working
by asg-pro on 2013-03-27 04:51:07.1360

Hi phil,

it's almost two years since your post but maybe you can help...

I'm working on replacing the ICs of my Flextone HD 2 power amp boards. It's the ICs that are attached to the heat sink, right? Mine only have 3 legs but the Digi-Key part you mentioned seems to have 11... I also can't get the ICs off the heat sink.

Any help would be greatly appreciated!


The information above may not be current, and you should direct questions to the current forum or review the manual.