Behringer PMX2000

[Mickmac]

Hi
New on here please can anyone help
I have a Behringer PMX 2000 which has blown a hole in the piece of live track just after the IEC plug. I have tested the transformer which is OK and the 8 transistors which are under the heatsinks which all seem OK (not short) although one may have an open circuit. Could anyone point me in the right direction please

[The Dude]

Can you upload a picture? It can probably be repaired by bridging the trace with wire.

[Mickmac]

Hi
Thanks for your reply I can repair the track easily but my worry was what caused it to blow in the first place, it blow next right next to a solder joint on the live side of the IEC. I didnt want to repair it and power it up just in case it then blow something else don't have a picture at the min its work. What do you think should I just repair it and give it a try?

[DrGonz78]

Research and build a light bulb limiter. It will allow you turn on the amp and limit current flowing to the amp just in case there is a short still. If the incandescent bulb (60-100 watt) is glowing bright then there is a short somewhere. Then search to test transistors, diodes and resistors for gross shorts. If that trace is burnt up and it is leading to a transistor connection then that transistor is probably bad now. Don't just repair the trace and turn on the amp. Instead take precautions by using the light bulb limiter.

[g1]

In this case, often the solder joint at the IEC cracks and becomes resistive. The heat buildup causes the trace to burn.
That's if the burn is right beside or on the solder joint.
If you can still see the solder joint there and it is in good condition, then I would worry about something else.

[Mickmac]

Hi All
Thank you for your replies. It is right at the side of the solder joint but sooner than a burn it has flashed and the joint and small section of track are missing you can the the black flash marks on the clear plastic insulator. I have built a light bulb limiter and will try and power it up tomorrow, just one question I have remove the heat sinks from the transistors will they be OK to power up thanks again

[DrGonz78]

I have built a light bulb limiter and will try and power it up tomorrow, just one question I have remove the heat sinks from the transistors will they be OK to power up thanks again

You always want the transistors connected to the heat sinks when powering up.

[Mickmac]

Hi All
I have repaired the track on the amp with a piece of copper wire and solder. Plugged it into the light bulb limiter it flashed the lights as I turn it on then all went out and the amp was up and running.
Limiter
I had read of all different wattages rangeing from 60w -300w I went with 300w and used 3x100w bulbs 1 wired in series and the other two wired in parallel with the series.
So amp is working OK thank you all for help.

[DrGonz78]

Glad to hear it's working. The thought behind the light bulb limiter is that if there is a short in the amp it will react faster with lower wattage bulbs. If you use the highest wattage bulbs first then it might allow too much current to pass if there was a shorted situation. Either way glad it worked out.