Hello all I have an SVS PB12-ultra/2 home audio amplifier/subwoofer. This turns on sometimes after it's been sitting for a while, and sounds just fine when it turns on. If you turn it off let it sit for a few seconds, and try to turn it back on the power led doesn't even light up. I started checking some voltages with this power supply, and noticed it outputs both AC and DC. I am being very careful to not touch or cross anything I shouldn't. I've been digging around the internet, but have not been able to locate any schematics or much info at all around these amplifiers. I don't have much background on the AC side, but I ahve some experience with car audio amplifiers. Looking for some tips or pointers to even narrow down the issue.
Its impossible to get anything - and SVS don't have schematics or anything because the plate amps they used were sourced from another company. The inrush current limiters can fail, its worth having a look at them.
I was asked by a friend to have a look at his SVS (I think it was a pb12 but can't remember right now) and in the end, bought a replacement unit from SVS for about 400 or 500 or so. They supplied an adapter loom piece to bridge from existing connections in the sub to new.
I was asked by a friend to have a look at his SVS (I think it was a pb12 but can't remember right now) and in the end, bought a replacement unit from SVS for about 400 or 500 or so. They supplied an adapter loom piece to bridge from existing connections in the sub to new.
Ahhh that makes sense as to why they don't have any schematics now, and cannot find them online either. Thanks for that information! I just got a reply this morning from them, and they don't even sell replacement parts anymore. They informed me the best course of action would be to just buy an external amplifier, and wire the subs to that.
I picked up a capacitor tester today to check the ESR, and found 2 caps that fail completely along with 1 that has a very high ESR. So I'm going to check the surrounding components, and replace these caps. The 2 caps that completely failed the test also have a black soot (the high ESR one is a dark blue color) on them as well that I missed the first time as it's just a very light coating of it. When it powered up it worked pretty good, but that was very rare... so I'm hoping it's just these caps!
I picked up a capacitor tester today to check the ESR, and found 2 caps that fail completely along with 1 that has a very high ESR. So I'm going to check the surrounding components, and replace these caps. The 2 caps that completely failed the test also have a black soot (the high ESR one is a dark blue color) on them as well that I missed the first time as it's just a very light coating of it. When it powered up it worked pretty good, but that was very rare... so I'm hoping it's just these caps!
I think I spoke too soon. caps seem good, but something poofed with some small flashes on the board around those caps. :-|
Something is back feeding or shorting through the case itself. I let it play taken apart on my desk for around 30 minutes or so while working great and powering on even if I turn it back on right away. Onto more investigation between the PSU/main board and these audio boards to why.
Hello,
i think SVS should help you a little more! At least to the level that you will surely buy their products again once you decide it is time for a change.
I have been using two SVS subwoofers for a few years now without any issues so i guess i am lucky.
Greetings, Eduard
i think SVS should help you a little more! At least to the level that you will surely buy their products again once you decide it is time for a change.
I have been using two SVS subwoofers for a few years now without any issues so i guess i am lucky.
Greetings, Eduard
You'd think that, but as woodturner mentioned SVS doesn't have any schematics or anything with these amplifiers anymore. I did figure it out though as it worked perfectly laying apart on my desk. I discovered that the main power supply board was severely warped when mounted in the case, and since this is from like 2004 old age plus it being warped was getting the best of it.
When it was mounted in it's case the 170v trace that had lifted slightly was arcing to the 30v pad for the capacitors. There's 3 50v 47uF caps on the output side of the power supply board next to the 5 pin connector. That's where my problem was, and the plastic center mount I shaved down so the board would sit flat with the 4 screws that hold it down. I cleared out all the bad section that was burnt causing some arcing as well. Working perfectly fine now all mounted back in it's case. I had it playing for around 30 minutes on my desk mounted in the case, and powered it off/on a few times as well without any issues so far as well.
Onto the next project!
When it was mounted in it's case the 170v trace that had lifted slightly was arcing to the 30v pad for the capacitors. There's 3 50v 47uF caps on the output side of the power supply board next to the 5 pin connector. That's where my problem was, and the plastic center mount I shaved down so the board would sit flat with the 4 screws that hold it down. I cleared out all the bad section that was burnt causing some arcing as well. Working perfectly fine now all mounted back in it's case. I had it playing for around 30 minutes on my desk mounted in the case, and powered it off/on a few times as well without any issues so far as well.
Onto the next project!
Well done on that fix.
In my case (it was a friends sub) he went for a replacement from SVS - a sledge amp. There were components burnt out on a small daughter board, SMD stuff that was charred and gone, and no hope of finding out what was there. So between no schematic, pads burnt, no idea what the components were etc, it was curtains for that amp. Replacement worked a treat though.
In my case (it was a friends sub) he went for a replacement from SVS - a sledge amp. There were components burnt out on a small daughter board, SMD stuff that was charred and gone, and no hope of finding out what was there. So between no schematic, pads burnt, no idea what the components were etc, it was curtains for that amp. Replacement worked a treat though.
yeah for sure! if this one was burnt up like that it would have been hopeless. I was tempted to go through everything and document it, but from what it seems most people just replace them or buy something new from the looks of it. If it blows up again it'll just get replaced with something newer, but for less than $5 and some time I'll take that. haha