Behringer Repair Went Up In Smoke Electronic Explosions - Europower PMX1000

I bought 3 Behringer mixers at the car boot for £25 this PMX1000 was turning on and shutting down. I found a shorted diode and blown resistor but I don't think that was all the problems this one had.
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[@MAXEMUSCO]

You didn’t give up and then it gave up on you! 😅🤜🏼

[@RetroElectronicRepair]

It sure did Max 😂

[@MAXEMUSCO]

@@RetroElectronicRepair your a trooper though geez! I would of ended up smashing it up as soon as I realised I didn’t need to take all those bolts n bits off! 🤣🤜🏼

[@RetroElectronicRepair]

😂😂😂

[@chrispike7249]

This is interesting to see you attempt to fix these Behringer mixers there i know nothing about electronics but im fascinated watching you trying to fix them Lee 👍

[@RetroElectronicRepair]

Thanks Chris, just goes to show I'm not always successful and everyone loves an explosion with some smoke.

[@LucasSuter]

Hi - I have the same mixer and last Saterday hi is blown up - smoke and dead. I found out that the SMD R59 and R59 looking black but I messured 21MOhm - ist this thrue? Beside that, one part is blown out and the leads are broken and the index is missing ;-/ now I don't no whitch part it is - on your video time 29:48 place right of your fingertip and down from R59/R58/R67/R68 what this is? I hope you can advise me whitch part I have to get THX

[@sw6188]

I've been repairing domestic and professional electronics for 45+ years. I hate working on these because nine times out of ten it's a fault in the power supply. They're fine while they're working but once they start giving trouble it never seems to stop. To start with, that diode which keeps shorting is an indication of too much current being drawn by that switching regulator, and the cap and IC blowing backs that up. As you say, for that cap to blow it must have had more than 450 V across it. You'd need to monitor the voltage there and scope it to see if there was any excessive ripple current. Looking at the schematic, only three things stand out - either excess voltage at that part of the circuit, a dynamic short on the vaux rail or a faulty TOP221 IC. I have had similar ICs fail but usually they don't work at all.

[@RetroElectronicRepair]

Thanks for the detailed comment, at least I now know I'm talking some sense and learning as I go. One day I will get a scope and learn how to use it, I wish I had at least measured the voltage on that cap and diode as it did blow another diode off camera. I should have really investigated that a bit more.

[@sw6188]

@@RetroElectronicRepair You're on the right track and have the right attitude when it comes to repairs. A power supply like this however isn't something I'd recommend for a novice to try to resolve. I have some special test equipment including a current limited high voltage supply, so I can run things up without the risk of them going bang. It allows testing under controlled conditions. Some (not all) switching supplies like this you can use a dim-bulb with, but others (especially those with auto-voltage-sensing on the input are a no-no for using the dim bulb. The problem with supplies like this is they go bang very easily and everything has to be right or you will just keep chasing your tail and it soon becomes expensive.

[@MrCobo04]

Been there all too often. Dodgy components that test good in and out of circuit that fail under-load. Causing all sorts if issues thats life and electronics. . You can only do the best you can. So experience eh. Just remember and carry on.

[@RetroElectronicRepair]

Yep, it's all more knowledge and experience. Thanks for watching and commenting.

[@Beyondact]

Blown caps smell so bad and you can not air that stuff out, just have to wait it out for a week. Also lies, I am sure we all learned something. If not something new then relearned, caps going pop is scary as fuck every single time.

[@RetroElectronicRepair]

Haha thanks mate. This one didn't smell too cad for some reason, the smell was gone in an hour. That was the first cap I've had explode and I jumped out of my skin! hahaha

[@Beyondact]

@@RetroElectronicRepairahh its your first and it didn't stick to the room like a bad egg for a week. That is depressing way to loose your cap virginity. Well here is hoping for the next one :)

[@tomixq]

The cause of diode and capacitor failure is too high voltage in the diode and capacitor circuit.

[@TatPeddler]

Hate it when this happens. Sometimes I throw the item out the door because of the smell. It lingers for a good few hours!

[@RetroElectronicRepair]

Some components smell a lot worse than caps. Thanks for watching and commenting Derek.

[@danielsaturnino5715]

It blew up because the power amp had no load on the output and you had the "amp" button set to either main or bridge. I believe you can use it without a load on the "monitor " position.