behringer pmp 3000

[anthillrich]

hi, i am the unlucky owner of a behringer pmp 3000 mixer/amp.

at a show a couple weeks ago, our mixer served double duty as a smoke machine, and mixer. there is actually a "video clip" of this thing smoking up in the middle of a song on my bands web page. my singer thought it would be funny to post it. i was not laughing tho.

anyway, i opened it up, and discover two(of 4) 4700 uf caps had sprayed their contents all over the place.

there are also 4x 2200uf caps that look ok.

i looked around a little in there and i also found a broken/burnt trace on the SPEAKON connection board. It was on the "b" side of the board between a 600v triac and the connecting pins from the power amp.

aside from these obvious problems, everything else looks ok.
i took off the covers over the pwr supply, nothing looks burnt or broken.
the actuall mixer portion of this also seems to be ok.

as a side note, no fuses were blown either, which makes me wonder...how bad does it have to get before they blow?

i was wondering if anyone has any experience with these, and would offer any usefull advice.

as always, i'm grateful for any help.
thanks, rich.

[Enzo]

I have to assume you are talking parts on the power supply, rather than the power amp. Power amp doesn;t have large caps.

First, this is a switching power supply, and it DIRECTLY rectifies the mains for is primary DC. This is extremely dangerous to work on powered. Please use an isolation transformer and be careful.

The 2200uf caps are the filters for that mains DC supply.

The 4700uf caps are for the +/- rails for the power amp. If they blew up, check the rectifiers associated with them - dual rectifiers D6 and D9. Look on the heat sink for them, I believe. Usually load problems don't affect filter caps. Are they both on the same rail? Or one per polarity? I'd be they are parallel on one rail.

There is very little in that secondary circuit other than the rectifiers and filter caps. A couple mylar caps in parallel with them. There is a 1 ohm R15 in series with the center tap, find it and make sure it has not opened.

If you repair that damage, you can test the power supply unloaded. But you must disconnect all the loads. The high voltage rails are the yellow/red/blue heavy wires, I think ther are two of those Molex connectors side by side - one per power amp channel. But there is also a small wire connector to the power amp - 6 pins for the low voltage and control signals. Disconnect that also, otherwise the power amp can tell the PS to shut down.

There is also a 6-pin for the mixer section. It has different voltages on it from the power amp one. You can leave the power amp disconnected and operate the mixer alone if that helps.

The Power amp connector 6-pin is thus:
1. +12
2. gnd
3. -12
4. +V
5. -V
6. off signal.

And the three pin ones are +V, gnd, -V.

There are a couple 22 ohm cement power resistors standing up on the PS, R11, R12. Make sure they didn't crack open or burn out. They are the soft start on the mains input.

MAke the power supply work first. But I fear your power amp may be burnt as well.

You found a burnt trace on the speakon board. That points at amp failure. First, is the triac shorted? It is a crowbar across the output, and if it senses DC there, it will trigger and short the output. Numerous amp makers do this. It prevents your speakers from catching fire. It usually gives its life doing this.

Look in the power amp. Are any of the MOSFETs on the heat sink shorted? It is an odd circuit, the + side is a pair of 9640 MOSFETs, while the - side is a single 250. I don;t know why. That is usually what fails. Ther is also a surface mount power resistor that can charcoal on you. It is a 0.03 ohm (seriously) R137 or R138, depending on the channel. Check it for open or damage.

[anthillrich]

thank you Enzo. your replies are always helpful.
i have not powered this up since the "incident", and my experience with these types of pwr amps and switching supplies is very very limited.

i am a fairly good parts swapper tho, and i have good tools to work with, so im not shy about doing the actuall parts replacement.
I am not planning on powering it up while i'm working in there, but i do appriceate the warning about high voltages.

the two caps that blew look to be on the same "rail" in parallel like you said.

i have not opened up the "amp box?" portion, but i am guessing the long heat sink running along side this section is where the mosfets are? there are quite a few heat sinks in there, so thats why im asking.

i will check all of the things you suggested, and replace what is blown on the pwr supply. then per your suggestion test the supply un-loaded.

i'll give a report back and let you know what i found. although i fear i am way over my head here.
thanks again Enzo.
rich.

[anthillrich]

i had a chance to check some of the things you mentioned. i was hoping to learn a little more if you dont mind.

1st. R15 is a wire jumper on this. no resistor fitted?

2nd, the .03 ohm smt resistor is indeed burned( on side b). i cant seem to measure it accurately( on a or b side) tho. where could i get these?

3rd, the 250n mosfet is shorted , and a 330uf cap(c113) is blown open. literally. The (2x) 9640 measure the same as the "good" side of the amp. I also noticed a strange looking 478n capacitor(C7) connected to the bad mosfet. Should i change that also?

as always, i thank you for your time, and willingness to share your knowledge.
rich.

[Enzo]

If R1 is now a wire, chances are it is not open. And your center tap will be making a circuit to ground as it should.

Can't measure 0.03 ohms? I don;t doubt that. But it is essentially a short circuit. Three hundredths of an ohm won't read any different from touching your meter probes together. It is either burnt open or it is OK most likely.

0.03 ohm - same thing as 30 milliohms - surface mount resistors? I'd look in Mouser and Allied

C7 is a 470nf cap. DOn;t know why it would be damaged, but for the small cost of the new part, why not change it? It is wired from rail to rail, which is the source connections of the MOSFETs as well.

I see C27-30 as 330uf/100v. I don;t spot C113. Ah, there they are, listed as alternative positions for local filters. Same electrically, different spots on the board. Those caps are across the rails.

[anthillrich]

thanks again for the info.
i was trying to find parts, and i see the name Mouser come up alot on the forum. when i checked for some of the parts, they had a minimum order requirements on the caps(like 300) and such.
so i checked and found Digikey. they seem to have everything i would need for the job, without the minimum order.
are they a good choice? any other suggestions?

i want to order the following items:

IRF9640PBF-ND MOSFET

IRFP250NPBF-ND MOSFET

2N6348G0S-ND 600V triac

P10782-ND 330uf 100v

P6812-ND 4700uf 100v

also, i wanted to order it all in one shot. I realize i have to fix the pwr supply 1st, and then the obviously shorted mosfets, and triacs.

Are there any other parts you can think of that i should order as a precaution? i realize you dont have a "crystal ball" to look into, or anything, but perhaps something im not seeing that typically blows up in these things.

i truly appreciate all the help you have given.
thanks again. rich

[Enzo]

Mouser:

330uf/100v radial cap - 16 different to choose from, all with 1 piece minimum, ranging 78 cents to $2.10 each

4700uf/100v snap-in radial - two, both currently out of stock but minimum 1 piece.

2N6348 - in stock, $1.31, 1 piece minimum

IRF9640 - in stock, $1.30, 1 piece minimum

IRFP250 - in stock, $2.61, 1 piece minimum


I am not suggesting anything is wrong with Digikey, they are a fine company to deal with. But you might want to refine your searches at Mouser, because there are not many things we need from them with large minimums.

I have no ideqa what else you might need, other than check the resistors in the area of the MOSFETs for any burnt open. COmpare to the other channel.

[anthillrich]

thank you Enzo.
i dont want to be a pest, but i have a few more questions if you would.

I found another burnt trace on the pwr supply board. It is on the secondary side of TR2. It goes to the + side of two of the 4700uf caps. (the two that did not explode).
on the pwr supply board, you had mentioned to check R15 for open. I responded that it was a jumper wire(it is). that is on the trace that burned open.
there are two surface mount caps(C52 & C53) that have been blown off the board as well. the more i poke around in here, the more i find wrong. good learning experience tho.

my questions are: how in the world can i test TR2 to see if its good/bad?
or would it just be better to replace it? and with what? i tried finding a parts match for it with no luck.
and finally, could you tell me values for C53, 52.

I WANT TO THANK YOU AGAIN FOR ALL YOUR HELP.
im not a repair guy, and i dont own a shop or anything. i just like fixing my gear when i can, and this forum has been an incredible learning aid for me.
thank you again.
rich

[Enzo]

TR2 is the last thing on my list of suspects. besides, you won;t find a TR2 anywhere. Even from behringer, if I just had to have one, they'd take six months to a year anyway getting one here from China. We would scrap the unit or replace the power supply as a complete assembly.

D6 and D9 look like transsistors, but are really dual diodes - half bridges. They should be on the heatsink in the power supply. The ends are wired to the TR2 winding, so its low resistance will be across them, bbut make sure neither leg is shorted to the center. A shorted rectifier could blast caps with reverse voltage.

The 15 ohm/jumper is the connection from the TR2 center tap to ground. All traces to that point are ground. They will connect also to the center pin of the two three-pin molex connectors for main amplifier power. If that trace burnt up, then excess current flowed. Between shorted power supply parts and shorted amplifier parts, that's not hard to believe.

C11,C17 are the main 4700uf filters on the +V rail. C52 is 1uf and parallel to them. Also parallel are C50,C51, 10nf each.

C21, C31 are the main filters on -V rail, with 1uf C53 in parallel, and also C54,C55 10nf.

[anthillrich]

thank you again Enzo.
i did test D6 & D9. They measure O.L. from center leg to each side, and revers the leads they show a .4 drop on each side.( i used the diode checker on my meter). i think thats right, but i suppose they probably took some heat when this supply blew up. Should I replace them as a precaution?

i was also wondering if i could purchase complete assemblies from you( pwr supply, pwr amp ect). i dont know if thats something you could get/sell, or do i have to deal with Berhringer directly?
i would really like to try and fix what i have here, (it would give me great satisfaction), but if i cant, i'll need to try something else. i will eventually need this thing to work, as im borrowing equipment in the meantime.
thanks again, rich.

[Enzo]

I am an authorized service center, and I can;t get boards, so good luck. I either fix something or it doesn;t get fixed, pretty much. Behringer won;t sell you parts direct, but they could tell you if they have something to order or not.

You could check with John Frondelli, who posts here. His dbm services in New York often has more parts that Behringer itself. But as a rule boards are not available.

[anthillrich]

Thanks for the reply.
I kind of figured buying the board would'nt be an option.
i'll give it a go and post my results. thank you for all the help.
rich

[galvy]

i too have a pmp 3000, but with a different problem. my daughter knocked a speaker stand onto the mixer console and the impact broke the circuit board of the mixer half. in disassembling it, it seems possible to still use the power amp, as it is safely housed below the mixer in a seperate chamber. how can i identify the function of the pin sockets that connect the two compononents? there are two plugs that need to be disconnected to separate them.

[Enzo]

There is a power amp assembly, the mixer assembly, and the power supply assembly. The connections between them all ought to be intuitive.

There should be a pair of heavy wires from amp to power supply - the main power for the amps. There should also be a smaller 6-wire connector from power supply to amplifier - the low voltages and control signals.

There will be a couple small little cables with 4 pin connector on end from mixer down to power amp - the signals.

And there will be a small 6-pin or about that many pins from the power supply up to the mixer - the power to the mixer.

SO as expected wires from powr to the amp and mixer. SIgnal wires from mixer to power amp.

[ssleslito]

i own and at this moment have a behringer opened up because of the same problem you have and ill tell you that 6 electronic shops and all the guys at the forum have not successfully fixed these mixers(actually some of you actually have fixed these but as mentioned it's a detailed task) and its not that its difficult its a manufacturing design flaw in the second board at the output A and output B ports inside the mixer.this board which processes power output from the mixer console out to speakers cannot handle the dual 600 watts (1200 total watts) that is running through it and blows the main coils if you replace the coils it will blow when and if you hit a low/high frequency and it usually happens in the middle of a show when you up the bass or the highs which cause the main transformer/resistors to process too many watts to the coils,either the resistors or the coils blow so the guys at the music/electronics forum are exactly correct but you can get the main board for $44.00 at amazon or ebay so you wont have to spend time and money replacing resistors etc.