QSC Power Amplifier PLX3402 (Part2): Operation successful, patient dead! BEB #44
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- čas přidán 11. 09. 2024
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Welcome to the Beautiful-Electronics-Blog, BEB.
Free teardown videos and education.
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In this episode:
Follow-up to BEB #27. The QSC amplifier PLX3402 is back on the bench. This time I have all parts. I even managed to repair the PSU. Will it be up & running again? Chances are... NO.
You will also see:
IR2110 PWM HIGH AND LOW SIDE DRIVER by International Rectifier, Switch mode power supply, bootstrap operation, SG3525A Pulse Width Modulator Control Circuit by ON SEMICONDUCTOR, Sanken RBV5006 Full Wave Rectifier, Weller WSP-150 solering irion with FE fume extractor hose, Tektronix TBS1052B-EDU Oscilloscope, Keysight 34450A multimeter, magic smoke.
Happy birthday Clemens (if you happen to read this on monday).
I know that this productions is not brilliant. But please be fair, and don't compare my moderate quality with those of fulltime-youtubers. Still, this production took me several days to roll and edit. I did my best to give you 20 minutes of electronic related entertainment. I am receptive to constructive feedback, but yeah, practise politeness.
Script, Camera, post production: Max
Recorded between 3rd of November 2016 and 20th of December 2016 in Dobl, Steiermark. Edited on 31st of March 2017.
BEB #27 QSX repair part 1:
• QSC Power Amplifier PL...
channel of the week: blancolirio
He's a brilliant engineer and 777 pilot, informing about the Oroville dam desaster.
/ @blancolirio
Just love your calm when you hear relay going on and off and me knowing it pushes 3 times more current than it supposed to!...😂😂😂
Hey Max, your video was entertaining and helpful. My PLX3602 QSC Amp had the same problem of cycling on/off as yours without the catastrophic failure of the main rectifier circuit. I found roughly +16.vdc on Ch2 speaker output which was being caused by Q79 shorted across all 3 leads. It didn't 'let the smoke out' as usual, but 'wet itself' instead! There was a puddle of clear liquid under the TXTR when I removed it, and everything else was dry around it. Part is on order so we will see.
thank you for your comment. it means a lot to me.
All the best with your amp!
"Reinstall the rectifier"
That goes on my list of "random confusing things to say".
Like "calibrate the calibrator" ;-)
Hahahaha !! You are right.
:-)
Welcome to my channel!
That's why i never stop recording when i test under power, you never know when it blows spectacular ;), really nice Video! Super Max!
Thank you for your kind reply! Yes, I've learned my lesson the hard way. It would have been AWESOME if the bang was on video. A lot of smoke, darkness, chaos,...
;)
Was hoping to subscribe to your channel but alas I only understand English... =(
I'm so sorry
You know so much. Love your work. I'd love to apprentice to your workshop for a few months. That would be cool.
I would bet there are multiple bad output transistors. I have repaired many of these and if there was a power supply failure, it is likely due to shorted output transistors!
Retweet this!
Ing. You the best..
output transistors check... lol one at least is shot... this amps with this smps tend to blow it if the load(one of the rails) is shorted... it seems the current circuit and protection is not working as it should to protect the power supply, i think this is why it damaged the power supply initially. PS use socket for the IR and SG next time as when igbt blow take both with them... the damage would of been far less if the resistors would of been the smt...
thank you for your comment.
Yes, I was about to install sockets, but I could not find them. Wished the protect circuit was any better on this model.
I wanted to say ... it looks to me the protect circuit was not working properly, may want to look in to it... ussually is how this amps fail dirt and protect circuit not doing its job... what happenned is not normal...
love your videos so much, you put the funny part to them !! , hey so, did you repair it completely or it QSC PLX gone to the trash can ?
Nasty amplifier, SMPSU, over complicated, huge PCB with too much metal attached. Thanks for taking the time to put this online.
Thank you!
Unfortunately almost all of the new pro amps are like this. Aside from a power supply issue they are pretty much disposable. I guess that's the price one pays for getting over 5 kw output in 2 rack spaces that does not draw a crazy amount of current from the main supply
you can make a great story out of everything..i have to learn that...
Hi Clemens. thank you for your kind words.
Hilarious! Nice to see some humor in these repairs.
Thank you! You are welcome!
@@MaxKoschuh usted no sabe señor
Oh dear, I feel your pain! you know, it may be that it is just not economic to try to repair it. I've been there before with amplifiers, where you end up changing almost every active device and guess what- it still goes bang when you switch on! So, what next? buy shares in IR?!
Hi Alan, thank you for sharing your story. I am always happy to see your comments. The failed repair was a great loss, both for me and the owner. I decided not to charge anything for my work. And the owner allowed me to keep the broken amp. I may do a dissection to find the cause for the amp failure. Shall I?
Ing. Max Koschuh That would be good Max, yes please!
Yes please. I am in the middle of trying to get mine to turn on. Switch didn’t seem to work so I unplugged it to turn off, for years. Maybe 2-4. Then wouldn’t turn on. These just might be my favorite amp, save the venerable Crown DC300. But seriously, bang for the buck and the weight, can’t be touched, or at least COULDN’T, back in the day. 21 lbs, 1150 watts per side at 4 ohms, thousands upon thousands of gigs, no problem with my others. Used to have a rack with 6 x 3602s. JBL VRX 932 LA, 2 a side, 4 ohms, 3602 in bridge mono across red terminals, JBL SRX 728 subs, same, basically 3600 watts x 4 and then 2 amps for 4 passive monitor mixes. Badass rack. Did a hard rock band outside one time within 300’ of my previous rock club 1000 venue where I had been the house engineer. They were trying to soundcheck some rockstars and they had to send someone over to ask me to turn my rig down. They had 3 over 3 EAW KF 850s and SB 850s. QSC baby. I want this amp fixed badly. These amps used to make any comparably priced amp look dumb.
so it comes out that if the final stage power transistors of any channels wasn't faulty, the repair would be succesful?
amigo gracias por tus videos me gustaria que montaras o me enviaras en diagrama de reparación estoy reparando uno modelo cx204v estallaron, y se desintegraron algunos de sus componentes muchisimas gracias espero tu ayuda
I have the same problem. No signs of any damage to the power supply. Tried to look for shorts in the channels but the only thing I could find is slightly lower resistance at one of the banks. Its only 0.5 lower so wasn't sure that it's the output transistors , maybe I should check the output transistors directly at board level. No power supply after going into a few on off cycles. I did observe output problems when switching into hi power mode. When in low mode every channel worked without a problem. ( I have 4 of them DCA 1644
Did that variable transformer come with that label saying that it is not an isolation transformer?
the Variac came without any labels.
I thought it will make sense to make clear that this is no isolation transformer.
For testing the IR2110 you didn't need to build in the IGBTs. You just can connect the to collectors together.
But I think it isn't necessary anymore :/
Hi Keks :-)
Thank you for this hint. I'm not a pro on switch mode power supplies. But I was so thrilled when I got it working again. Too bad it was a broken amp, that forced the PSU into protect mode.
Ich auch nicht, aber der IR2110 ist mein lieblings IC. Die 2A Ausgangsstrom sind ziemlich viel und da spare ich mir einen GDT, der viele Probleme machen kann (Kapazität und Induktivität, und dann sollte er noch schnelle Schaltzeiten haben, keine so gute Kombination) ^^
heh heh heh
QSC PLX 3402 mở nguồn ok, sau 1 phút tự tắt... mong Bạn hướng dẫn nhé. Vref 5,1v ok!!!
I have a qsc plx 3402. Units power indicator lit when plugged in and turned on. Red clip led doesn't lit/ blink when turned on, fan not working, yellow parallel/ bridge mode led light doesn't lit even if unit is set on parallel/bridged. Any suggestion what the problem could be? Thank you
You installed non isolated type of igbt transistors
Sir I have Qsc Amplifier Model DCA 3022 Both Red Light blinking Kindly if you have possible then help me about solution
Hello, great video. I have a PLX 3402 at 110 volt, I would like to know if this can be converted to 220 volt. Thanks in advance.
Did you find out what caused this problem
Greetings to everyone! I'm just repairing a QSC 1609. However, I can't find a wiring diagram anywhere. Would anyone have any?
Die guten alten QSC amps waren praktisch unkaputtbar. Schade, daß Dein Kandidad in so katastrophalem Zustand war. Ist denn noch was draus geworden? Oder hast ihn aufgegeben?
Ich hab das damals mit meinem Kunden besprochen, und wir sind dann zu der Auffassung gekommen dass sich eine Reparatur nicht lohnt. Ich hab sie dann billig auf ebay vertickt, als Ersatzteilträger, und der Käufer hat sich riesig gefreut weil er Teile gebraucht hat. Am Ende war doch irgendwie alles gut :-)
Sir my trasister is heat and my 5032 trasistor heat and my diod 5399 Line is shortage in qsc CX 404
Hi did u check the main filter capacitors for shorts?
no. but I can do this in the autopsy. there will probably be a part 3.
Ill look forward to that.
you should check all power transistor one by one, i'm sure 100% there are bad transistor or shorted
Never rush to turn it on! There is a cause why psus fail! Usually is a short!
You will not see signal on the hi side of the mosfet driver IR2110 as it's boot strapped.
Iv'e fixed many of these
I'm sorry but you can't buy a "big" IGBT like on the primary for ... 3$ ! These IGBT are very expensive (arround 12$), and, for a good repair, don't buy these critical parts on ebay (it's the same part on Aliexpress ...). This are fakes.
Schade, aber es sind ja noch mehr Teile da ;). Warum kauft man sich ein TBS1052-EDU scope?
Hi, freut mich Dich wieder einmal hier zu sehen :-)
Ja, schade wegen der defekten Endstufe. Ich werde das Gerät später vielleicht nochmal komplett auseinandernehmen und auf Urspungssuche gehen,
Aber kann sein dass die Protect-.Schaltung schlecht ausentwickelt ist? Ich meine,... die geht an und aus und an und aus, klar dass dann irgendwann das Netzteil eingeht. Protect sollte in protect bleiben. Wenn es sich nach Trennen vom Netz nochmal einschalten lässt und in pritect geht, ok. Aber automatisch wieder probieren, ohne Pause,...find ich nicht gut. Was sagst Du dazu?
Für das Oszi gab es einen extrem guten Deal. Das ist jetzt knapp zwei Jahre her. Es hat mir damals keinen Cent mehr kostet als ein No-Name Gerät. Ich weiß jetzt die Details nicht auswendig, muss ich im Büro nachschauen, aber das war ein echter Knüller. Bei RS war das. Würde ich zu dem Preis jederzeit wieder kaufen.
Da muss ich Dir vollkommen recht geben. Eine Sicherheitsschaltung sollte "latchen". Dazu braucht das Latch aber irgendeine andere Stromversorgung die von der Sekundärseite unabhängig ist. Ich könnte mir vorstellen, dass die Entwickler da gespart haben. Einige Netzteile haben dazu speziell einen Optokoppler, der ein Latch im Controller auf der Primärseite auslöst, die Controller sind aber teurer als so ein Standard SG3524 oder was da drin ist. Das Latch fällt üblicherwise erst wieder ab, wenn man den Controller , also den ganzen Verstärker spannungslos schaltet und der Primärkondensator entladen ist.
The highside fet of the ir2110 is bootstrapped and you didnt place the fets, it wont show a drive signal ever🙃.
Continued watching an saw you figured it out at 16:12✌️
if only one Rail ist shorted to the output nothing should draw so much current, only when positive and negative rail are shorted out. Not so nice to see that bang, but it happens...
Maybe one channel was damage. Then you leave the amplifier on, off, on, off(protection) and that damaged the power supply. When you check one amplifier of that type you need to repair the channels first.
That's exactly what I experienced with an amp bought on ebay , is that an expensive fix ? No power now. Dca 1644 amp
ouch that got ugly quickly
Just waiting for a part 3...
I need to shoot a video about a all-in-one Asus PC which actually HAD FLAMES in it.
Spoiler: beyond economical repair.
heh hehe heh, do you have that on video :-)
Sadly no, it was somebody else computer I was given for repair, I will be doing the autopsy.
If you bought those parts on ebay they are fakes
lol that was other stuff that got
burned by acytelyne ... electronics
doesn't burn that way
Giant analog computer...
:-)
Yes, awesome!
Good try Max that was entertaining .. guess QSC doesn't mind catching their amps on fire that protection mode should have stopped that relay cycling .. it is probably time to let that one go and use it for parts
Thanks for the hard work on the videos
Thank you for watching, and your nice comment.
Please please don't ever open a box like you did in the intro with the razor blade knife, I'm just looking out for you and your fingers
17:15 STOP STOP STOP ! ! ! .....you forgot the insolators?????? You shure The C (Collector) its both at het Headsink???? And Check al output Transitors of short at Headsink! The can be a bad mica of terminal insolator. Check or the Headseak at the Earth of ground of the Amp. Be shure Negative output from its a the same of A and B channel its the same ground. If not NEVER make a general Negative for Speaker A and B, but make a separate negative/zero tot the speakers from channel A & B.
there is a large insulator plate between the heatsink and the transistors :-)
schematic please
email address please :-)