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The Behringer B2301 Repair


B2031In the last episode of the B2301 saga, we watched in horror as capacitors exploded in our beloved monitors. Now begins the task of cleaning up the destruction.

As a quick recap, I had a Behringer B2301 studio monitor fry on me. It turned out to just be some snubber capacitors across some rectifier diodes exploding, so there was no significant damage to the unit. Chances are the unit would function just fine without them, but I’m replacing them anyway since there is no other filtering on the voltage rails which supply the amplifier ICs.

B2031 repair 1

That being said, I picked up 8 beefier, non-explosion rated capacitors from Digikey. I also bought 8 new fast-recovery rectifier diodes. Because the new capacitors were so much larger than the old ones, I piggy-backed them on top of the diodes rather than try to fit them in the old PCB holes. This was also necessary because some of the tiny copper traces to the capacitors had been vaporized when the old capacitors failed.

B2031 repair 2

The old diodes and capacitors came out and the new diodes with their piggy-backed capacitors went in. I also took a few minutes to replace the stiffening capacitors. If you decide to replace these, realize that they are shorter than standard. I didn’t and ended up having to install some 1/8″ spacers between the amplifier chassis and speaker enclosure to get everything to fit.

B2031 repair 3

That is the end of this story. The monitors have been working fine since the repairs. This was a pretty simple repair; diagnosis was easy and treatment consisted of just replacing parts.

As always, make sure it is unplugged before you take it apart.

Update: The parts list as requested:

DigiKey p/n   Mfg. p/n       Description
1N5402GOS-ND  1N5402G        200v 3A Rectifier Diode
P10469-ND     ECK-ATS103MF6  10000pF (0.01uF) 250VAC Ceramic Y2/X1 +
P6686-ND      ECO-S1HA682CA  6800uF 50V 3000HR@105ºC Electrolytic ++

+ DigiKey indicates that they no longer will be stocking these Panasonic capacitors. As the time of writing, they still have plenty in stock but once they’re gone, DigiKey No. 445-2429-ND made by TDK should be a functionally equivalent. Any 0.01uF ceramic rated  200V or better should do fine, though.

++ These capacitors were slightly too tall as previously mentioned. A better replacement might be DigiKey No. 338-1649-ND made by Cornell Dubilier. They are shorter and should fit comfortably but are rated 3000HR@85ºC and have a higher ESR (68.0 mΩ versus 49.0 mΩ for the Panasonic) but should work fine in this application. They also happen to be half the price of the slightly too large Panasonic caps.

posted under Equipment, RepairIt
16 Comments to

“The Behringer B2301 Repair”

  1. On April 30th, 2010 at 1:11 pm broken Says:

    Wow, reading this has been tremendous help. One of by B2031 just crapped out on me. Same case as yours, with the fireworks and all. I opened it up and there was blowned caps exacly like yours. Luckily, i was able to find your blog and now in the process of repairing mine. Thank you so much for this resource. I would have never been able to repair mine without your help.

  2. On June 18th, 2010 at 10:10 pm Ivica Says:

    I had same problem but my pcb is irreversably damaged in that part. Where to obtain a new pcb? Thanks.

  3. On August 7th, 2010 at 8:19 am bryan Says:

    @Ivica – If the board is damaged, you might be out of luck. You might try getting in touch with Behringer to have them serviced.

  4. On August 13th, 2010 at 3:27 am Scott Says:

    Ivica, a PCB board for the B2031 I believe is part #Q05-25204-00674 as shown on Not positive about rev’s and it says it doesn’t come with Power Ics and is expensive $58.00 (might be cheaper than a new monitor).

    Thank you for the write up, one of mine did the EXACT same thing. I’ll order the parts and repair my bad one and preventitive work one the other one. My unit continued to work just fine with the blown/damaged capacitors (like you had suspected it might) but burning electronics is a smell I don’t like.


    Ed: I think the link Scott posted got a little mushed. Try this link.

  5. On October 19th, 2010 at 11:53 am ac Says:

    Hello. I have similar model. I’m interested, do you know what is the part in the last image in lower right corner. It has large blue “3” on top of it. On my board it reads OP1 next to it. I guess we could assume it is an op-amp but is this some custom behringer part or what, any better guesses?

    One of monitors also broke down. It’s b2030a and there are no snubber caps, the power IC are straight after the rectifier diode, and the OP1 and rest of the op-amps are behind 7815/7915. It went into short circuit. I removed the 7×15 regulator and the short circuit went away. I put light bulb in place of the fuse for test purposes. When there’s nothing on the secondary of the transformer, the bulb briefly flashes, sometimes, when power switch is turned or power cable is inserted when pw-switch is already set to power on. I read that this could be inrush current in the transformer when its powered. It’s just weird that it doesn’t flash the bulp every time. Before the monitor broke the fuse kept blowing every ~10 power ups. It had a 1A fuse, I changed this to 1.6A since the newer revision of same model has this value. Haven’t yet tested with proper load but atleast it didn’t blow up after some 20 power toggles.

    I wonder if adding just the snubber cap is enough, after all people are talking about those exploding! I’m interested if the some part such as metal-oxide varistor/transient voltage supression diode could prevent that.

  6. On October 21st, 2010 at 9:02 am bryan Says:

    I believe the part with the “3” on it in the photo is an optocoupler – most likely an LED (two of the wires) pointed at a CdS photocell (the other two wires) – that is used in the limiter circuitry.

    As for your transformer question, I would guess that you’re on the right track with the inrush current idea. The only explanation I can muster for why the bulb flashes sometimes and not others is based on *when* you flip the switch on. The AC voltage from the line isn’t constant, so if you apply power to the transformer when the voltage is trending toward a peak, you’re going to have a larger inrush current. If you catch the voltage more near a trough, smaller inrush.

    Your short circuit could be a bad voltage regulator. It is possible that something downstream of the regulator caused it to go bad, but it’s hard to tell without replacing the regulator and watching for smoke. Fortunately, they’re relatively cheap.

    The snubber capacitors exist only to take care of switching noise (a small AC spike) as the diodes go from conducting to non-conducting and vice versa. MOVs wouldn’t serve the same purpose since they rely on a relatively large voltage spike to break-over. A TVSS diode would put us back into the same boat with switching noise.

    I think ultimately the caps Behringer used originally were just under-rated.

  7. On November 30th, 2010 at 6:33 am ac Says:

    I’d like to do update on the short circuit on one of the b2030a, starting from the beginning.

    I don’t yet know exactly why the monitor went into short after some 10 power ups after having received it (it was used but the condition seemed alright and there were no signs that it had been opened up before, years of dust build up etc were intact).

    My first thought was that it was bad caps as that’s something quite common, so I replaced the large 3300 uf electrolytics and some smallers in the power side. Then I put it back together and still it was in short.

    After my last post I took out the regulators, tested them invidually to be ok and then put them back with lightbulb in place of fuse and the short circuit was gone. Then I put the circuit board back into the case and yeah you may have guessed (I didn’t), short circuit is back. So after this Itested resistance on the case which has a shield/ground wire or something from the mains to it and other probe on the IC’s that weren’t isolated (lm3886, lm4701). There was no resistance. Then I remembered that when I disassembled the still working speaker, it had plastic isolation sheet between both IC’s, in this speaker there was one only on the lm3886. Aha. So I put some normal transparent tape (not sure if this conducts the temp as well, it might also melt and go into short again..) between the heatsink and lm4701 where the original sheet should’ve been and now it seems to work.

    But I still have the bulb in place of the fuse since I suspect the spec’d 1A fuse still keeps blowing (it also blew frequently in the other “working” pair). I may try to go to the 1.6A that I mentioned previously permanently after I get some confidence that this tape-fix will do. (The lm4701 has over temp protection I believe from reading the datasheet so I’ll keep watch on if it goes on and watch for the light incase the thing shorts again)

  8. On March 9th, 2011 at 3:34 pm Ken Says:

    I just had one of my monitors crap on me just today, and I found your blog. I was curious if my experience was similar to yours.

    When my monitor crapped out, I heard a massive noise. I thought maybe it was just the signal being sent to the monitors – I am using Microsoft Windows after all – so I didn’t think too much about it. The sound continued to work.

    But then about 30-60 seconds later, I smelt smoke coming from the top of the monitors. I didn’t see the smoke – just smelt it.

    I decided to turn them off. Is this similar?

    I haven’t taken it apart. Is it okay to keep using it, or should I get it fixed like yours? I have no idea how to do any of this stuff.

    Please contact me if you can. You have my email address.

  9. On May 3rd, 2011 at 7:01 am Grant Says:

    My B2031’s have done exactly the same as this exploding caps . This is most useful item thank you very much indeed.

  10. On May 12th, 2011 at 4:26 pm Grant Says:

    Should that be 100000pf = 104 ? sorry I am sure you know what you are doing. And it is working .

  11. On September 12th, 2011 at 10:25 pm Paul Says:

    Hey, thanks for this post. One of my B2031As had some weird distortion and medium volume and low frequencies, I assumed it was a power IC problem and tried to replace one of them with a spare I had.

    I wanted to remove the old one intact in case it was not the broken one, but I managed to lift the circuit traces.

    I checked the schematic and tried jumpering the lifted tracks, but the amp no longer works.

    Now at least I have a part number to try and get a replacement IC.

  12. On October 30th, 2015 at 1:01 pm Robert Says:

    I tried to replace the LM3886t and it arks and sparks
    i insulted the screw on both sides
    but why is it sparking ??

  13. On July 2nd, 2016 at 1:28 pm Deck Says:

    I’ve got the same issue bang pop lightning and the decoupling caps look just like the photos but after swapping out the diodes and safety caps the speaker just blows the t2.5h250v slow low fuse by IEC inlet and I have never had a problem with a fuse blowing once since purchase over 10 years ago. any help or advice would be appreciated #sadface.

  14. On November 14th, 2016 at 10:15 am Karlton Says:

    I have a Behringer B2030A speaker in which the tweeter stopped working and turning it on/off results in a fairly large pop. I opened it up and found a small (~0.5″) blue piece of plastic (cap?) on which is written
    “KSD GR 85 C 10 mf 50v”

    I know nothing of electronics but am willing to try and replace this. Does anyone have a source and part # which would correctly replace the broken part. I cannot find “KSD” anywhere with a google search.

    Thanks in Advance


  15. On May 13th, 2017 at 6:18 am davidross Says:

    B2030 Truth frequently blows power fuse. All appears okay physically on PCB. But bypass capacitor on pin 8 of the 3886 is leaky. Anyone else had a similar problem?

  16. On January 29th, 2018 at 8:53 am Transformer guy Says:

    I see this site has been quite for some time but thought i still would try to get some answers.
    One of my 2031a speakers completely died, wont power on and i have trace it to be the transformer that is dead. Replaced the transformer from the other speaker and it worked like a charm.
    My question is if anyone knows the correct specs for the transformer? I have found spare bvehringer transformer but they are sold in the states and i live in Europa which they wont ship too and it seems impossible to find the correct specs for the transformer. All behringer transformer are sold as spare part to specific product without informing the specs, at least i havent found them so thought maybe someone here knows what the correct specs are?

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