Behringer PMH518M - using the mixer without the lpa1180

[felstermueller]

Hi Folks,
after reading a lot i finally found this forum with information about the lpa1180 module by behringer. So, i hope, you can help me.
Recently I bought a used Behringer pmh518m-"Powermixer" (in German), but it's broken - it has a "burned" lpa1180, i guess (seems to be a quite frequent failure). It destroys the main fuse (3.15 A) every time i try to switch it on (but now i ran out of fuses...). If the lpa1180 is disconnected, the fuse persits.
So, would it be possible to use the mixer/preamp without the rest? As I can see, it is connected to the lpa1180 through a plug with 6 cables (a red one, the others black). I think these include power supply? Can i use a foreign power supply (12V, 14.4V - how much ampere?) and then connect the mixer to another external power amplifier? Did anyone find out about the pins connecting a preamp to the lpa1180? Buying a new lpa1180 is to expensive, as i dont know, if the spare parts are ok.
Thanks in advance, sorry for my poor english
Andreas

[mozwell]

Yes you can.
If your power amp is not working & you dont want to repair it, remove T2, T3, T4, T5 (Page 6 location C7). The power amp will not drive a speaker any more, and wont draw current from the +/- 40V supply. The power amp is only 100W into 4 ohm from a +/- 40V supply anyway, so its no loss if you dont have it.
This way, you still have all the power supplies to power the preamp section of the mixer / amp.
You will need to make a small change to the AMP INSERT, or you wont get the mixer output signal there.
Short together X4 pin 1 & 2 & remove R226 (page 4, location C8).
A normal 1/4" mono lead will now plug into the AMP INSERT jack & give the signal for your power amp.

An external power amp will most likely be much better than the power amp included with this mixer.

[felstermueller]

Wow, you are an expert, mozwell! Thank you very much.
But before i can start, i have to learn to read that schematic better, and find some help in "soldering". But I see the advantages. Otherwise, if i'm afraid to fail, would it be possible to use the preamp through the six cables? By connecting them directly to he power supply and an additional 1/4'' plug?

[D1rtyD0g]

Hi Mozwell

Yes you can.
If your power amp is not working & you dont want to repair it, remove T2, T3, T4, T5 (Page 6 location C7). The power amp will not drive a speaker any more, and wont draw current from the +/- 40V supply. The power amp is only 100W into 4 ohm from a +/- 40V supply anyway, so its no loss if you dont have it.
This way, you still have all the power supplies to power the preamp section of the mixer / amp.
You will need to make a small change to the AMP INSERT, or you wont get the mixer output signal there.
Short together X4 pin 1 & 2 & remove R226 (page 4, location C8).
A normal 1/4" mono lead will now plug into the AMP INSERT jack & give the signal for your power amp.

An external power amp will most likely be much better than the power amp included with this mixer.

Hi Mozwell, do you have another link for the scematics you mention here as this link is now dead i think, thanks

[DrGonz78]

Here try these...