Pioneer VSX-520-K Protection problem
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Re: Pioneer VSX-520-K Protection problem
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Re: Pioneer VSX-520-K Protection problem
Look for something common to all amplifiers like the - rail that feeds the emitters of the voltage amplifier transistor via R227 10 ohm. And also the +12v rail that goes to the 7.5k resistors that connect to the input transistors' emitters.Last edited by rievax_60; 09-10-2015, 08:29 AM.Comment
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Re: Pioneer VSX-520-K Protection problem
Hey folks, im back after a long time due to work load. OK as for updates, i manage to fix the amp as on the power amp side, a couple of regulators seems faulty triggering the protection circuit. Now the amp powers up perfectly, all relays clicking fine.
BUT, I measured using DMM @ 200mV setting,
Left speaker output there's -31.3mV present while the right side -7mV dc offset present. What do i do now? Checked the big caps, they read just fine and measure as it should using a cap meter.
All the driver amp transistors seems to be fine as well as none blown or short.
Update : All surround speakers and center speakers, L&R speaker outputs are working perfectly fine with all under 10.0mV. Weird.
Could it be the big caps failing intermittently?Last edited by DjKrish; 05-10-2016, 04:27 AM.Comment
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Re: Pioneer VSX-520-K Protection problem
30mV offset is not going to trip the speaker protection relay, the trip point is usually around a Volt or two to trip the protection circuit.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: Pioneer VSX-520-K Protection problem
Minus 30mV present when volume at zero with no signal input and speakers unplugged. Ive let it run for couple of hours, still showing -30mV. Only the right channel. Left seems fine.Comment
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Re: Pioneer VSX-520-K Protection problem
That said, I just managed to cause DC on the INPUT of my VSX-520, taking out C206C with a loud bang! This is a good example why you should use the service manual, even when you're experienced and know what you're doing. I dived in without the manual, replaced the output transistors and also needed to replace the protection transistors as they were also dead-short. It has been well over a decade since I worked on electronic repair of this type and it seems things have moved a long way...
The protection trannies were marked C3200 and A992, which, back in my day you could have safely assumed would have meant 2SC3200 and 2SA992 but not now apparently! I should have used KTC3200BL and KSA992F - these codes didnt exist back when I did this for a living! I Feel a bit silly for not having checked - lesson learned the hard way!
I don't need the centre channel right now so I'm going to isolate B+ and B- for that channel, pull out the incorrect trannies and try again, if the rest still works I can order the right parts and use it 4.1 until they arrive lolComment
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Re: Pioneer VSX-520-K Protection problem
Hey folks, im back after a long time due to work load. OK as for updates, i manage to fix the amp as on the power amp side, a couple of regulators seems faulty triggering the protection circuit. Now the amp powers up perfectly, all relays clicking fine.
BUT, I measured using DMM @ 200mV setting,
Left speaker output there's -31.3mV present while the right side -7mV dc offset present. What do i do now? Checked the big caps, they read just fine and measure as it should using a cap meter.
All the driver amp transistors seems to be fine as well as none blown or short.
Update : All surround speakers and center speakers, L&R speaker outputs are working perfectly fine with all under 10.0mV. Weird.
Could it be the big caps failing intermittently?
Can you explain what cause the DC offset on Speaker output?Comment
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