Okay I think I follow. What's with D15-18? They look as though they rectify T3A. Confuses me as it LOOKS like T3A is a primary winding.? Is there some flyback being put to use here? Oh wait I see. OutA and OutB are being rectified to supply VCC for IC4 and other parts of the circuit too. But wait does VCC originate at TR1B?
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Behringer PMP4000
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I signed an NDA, so I cannot, but anyone already having the file and not signing the NDA can feel free to send it anywhere. ANyone has it and wants to post it, that's fine by me. I'd be more than happy to have more voices in this song. I'm not into "private repairs," in fact, I often get PM requests for private consultations, and I just tell them to start a thread. And Jazz, I do understand you were not scolding me.
T3A is driven by the IC, and T3B and T3C then drive the switching transistors. As far as I know, D15-18 are just clamps to prevent voltage on that winding from going past the power rail or "ground". They are not a bridge rectifier, so yes, I guess flyback protection is one way to look at it. For example D15, D17 connect to VCC, but they are not MAKING VCC, they are clamping the ends of T3A to it. If teh voltage at either end of T3A were to exceed VCC, those diodes would start to conduct and dump any excess into the supply. SO basically, forget they are there.Education is what you're left with after you have forgotten what you have learned.
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Looks like that last post was meant for my other thread. hmmm... not sure how that happened. Anyway I passed on finishing this repair. I couldn't find any problems with the meter and felt I'd have to start pulling diodes to see what brought it back. Don't have much time to keep with it, but this thread will certainly give me a more streamlined approach for the next similar repair that comes in. Mackie is gonna do an exchange on it. Thanks for the help. These threads have helped alot, as I fixed a different Behringer powered sub based on what I've learned on here. It had a cycling loud POP after being on for 10 minutes. I found a low negative low v supply. I disconnected the circuit from the supply and it was still low. After checking filter caps I ended up replacing a 7915 voltage regulator. fixed it.
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lowell can you send me schematisc or service manual of SMPSU29?
my email is: nedoh.miha@gmail.com
best regards
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Originally posted by lowell View PostThis unit when turned on all the leds blink, dimly, but they blink at about a 3 times/second rate. There is also a "beating" sound on all outputs that is related to the blinking. Not sure if I should even bother attempting a repair with it. These units tend to be a waste of time when it's not something I'm immediately familiar with. But if someone's repaired such an issue and has a clue about it let me know. Can't post a schem but will send one.
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This is as close aas ElektroTanya gets: BEHRINGER EUROPOWER-P0569 HCA2400 SPS1000 DPX PMP-1280S 5000 SCH Service Manual free download, schematics, eeprom, repair info for electronics
This site has a ton of Behringer schematics: http://www.electronica-pt.com/index....select/id,204/
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