Pt. 2 BOSE Amplifier AMP Repair Lifestyle LSPS PS18 PS28 III PS38 PS48 AV SUB Subwoofer 

Much appreciated! Thanks for watching.

Hi, the LED is located to the left of the red/white dip switches.

I have the same problem. I am wondering whether u got the problem rectified

More likely a MOSFET is bad.

I would be willing to bet, you have blown MOSFETS... Good luck buddy. The Eighties Nut

I have the same problem now, did you get your resolve?

U need to unplug the subwoofer for at least 30 seconds before plugged back in. I unplug both the receiver and the sub for 35 seconds each with the subwoofer being done last. It clears something and allows it to connect. If u ever lose sound unplug it and try that.

Yes, there was an adapter kit years ago on eBay it's probably still available on there.

moss fits look like ics

Hi, an amplifier MOSFET is typically mounted onto a heatsink (aluminum) to dissipate the heat that the MOSFET produces. That is why so many amplifier housings are made of aluminum as the entire housing is used to despite heat. MOSFET's have four terminal leads however many have three and the ones that have four at times you may use only three, as you can use the source (S) as body (B) MOSFET lead terminals are source (S), gate (G), drain (D), and body (B)

Did you fix this problem I am having the same issue

Same thing here. New fuses, no sign of burnt components. Dead

It is a true little workhorse that could live 100 years with out neglect or misuse , as long as it was not neglected. I have opened up over a hundred of these some look like a computer PCB that was never cleaned, others have moisture damage from being stored out in elements and finally, component damage from misuse.

@@EightiesNut my green light flashes what does that inficate

@@johnkintner1637 That it's communicating with the media center module, as in all is good! I picked up one of these btw Eighties, and it's fantastic. Deep, low rich bass down to 28Hz, SOLID, then steep roll-off. But my God does it sound incredible. I've owned, Klispch, Paradigm, Bang & Olufsen and heard the rest and these LS systems are simply exquisite. Mind you I've had and been into Bose's research and engineering for awhile now as a product buyer and always and constantly - back in the day anyways - would look into how they achieved their sound, and it's simply mind blowing stuff. Anyone who 'craps' on Bose simply doesn't have the remote brain power or understanding to, well, understand it. It's not that complicated of a concept to wrap your head around, but to most it's "voodoo magic" thus their simply "marketing" lmao, which is the complete opposite to reality. Anyways, I love the damn thing, best 3rd Lifestyle system I've ever owned, with one being now owned by a buddy of mine and another sold to someone for a good deal back in the day. For music production I use my Paradigm monitors, for earth-shattering lows and crystal clear detailed highs, I like my Jewel-cube LS system. Thanks again for the reply man!! Bose really makes solid equipment and, honestly - I prefer his older designs. Just classic super industrial designs that were overly complex, but for real reasons, I love intricate shit. And it's what I grew up with when I was heavily into Bose. Anyways, peace my man

​@@EightiesNut When you saw low-level input connection, it's actually all digital data - like USB. It's not line or speaker level outputs to be amplified, but rather talks to an actual computer that syncs via firmware within the module to the media console, or 'head-unit' as you put it. I saw another post where you're mentioning it working with a Denon receiver - it'd blow it, I mean as far as I know from my computer side of knowledge of sending watts to what is essentially an actual RJ-45 port like a PC or Mac. However, there are converter cables for this very thing Zahoor, on eBay. Not sure how well they work but supposedly many sell and people like 'em. It is possible. But again, I think it somehow convinces the bass module it's all connected and takes in analogue input additionally through the cable, I don't know. I just know there's a literal computer inside the AM box that does all the talking and processing, not simple pass through db amplification.

Hi, yes at some point I do need to make a video of the internals of the enclosure. Things have been a bit crazy lately, but I will get to it.

Hi, is it doing this at low levels, high levels or all levels of volume?

It does it all the time. It does it on a standalone plug-in power source and hit switch to on and automatically starts doing that. It’s quite loud to.

I suspect that one of the two speakers has blown. With the power off take the front grill off and press the cone in. Your fingers should be as close as possible to the dust cap. Make sure you are pushing down evenly so that the push is concentric to the circular magnet, if you feel rubbing or hear a scratchy sound the speaker is blown, if you push down unevenly and lack concentricity then the test results would be inaccurate as you would be physically causing the rubbing. This test is not the ideal test, but it will get the job done. The ideal & most accurate test would be to remove the speakers and check the impedance, however you know from watching the video how much of a pain it is to remove the speakers, so we must compromise.

Initial test. I do not hear or feel rubbing or scratching. I’m going to take the speakers out and check impedance. Thank you so much for your info. Maybe I can send you a video of what it’s doing.

Ok. So the top speaker is at 1.1 Ohm and the bottom speaker is at 1.2 Ohm

What are the locations of the clips you are talking about?

Hi, you need a Bose receiver it will have the inputs that are required for the output from your TV.

Hi, your best bet would be eBay.

Was able to find engraving - f4al250v. This is a fast blow fuse.

Hi, You should be able to find it on eBay.

Hi, Yes it can, however I am not sure it would be worth the work.

@@EightiesNut Thanks

I have one and i can sel you.

Hi, Is your amp powering on?

@@EightiesNut no

@@richardmiranda9719 Just to make sure No blinking indicator LED next to the power plug on the amp? I just want to make sure it was not something down, other than the amp. If it is not so, yes I would check the fuse.

tested fuse its good, now what is it garbag

Thanks buddy!

The amp might be fine. Try hooking up any speaker to the output on the bottom of the amp just to make sure also make sure it is not the output on the receiver that is bad many times the issue is with the receiver. and at times it's the drivers that's rare but I have seen it. In your case, I do not think you have blown speakers as in most cases blown speakers will damage the amp. Without checking it out myself I would guess the issue is more likely with the receiver.

It could be so many things, but if I had to guess without physically inspecting it I would think a bad ground/open circuit or a failing cap.

Hi, by normal do you mean RCA jacks?

Thanks! Happy I helped!

Hi, Yes theoretically it would work just fine, however you biggest obstacle will be the input to the Bose amp from your Denon receiver. The Bose uses a specific DIN input cable for input from the Bose receiver. The task at hand would be to decipher the DIN input cable wires. It is not super difficult, but it will take time. If you attempt it, let me know how it went?

Hi, the next step would be to test the transformer and then each MOSFET Good luck.

In this case my abilities aren't good enough, I will have to take it to a professional now. But thank you so much for the fast answer and for this vídeos. They were and are really very helpful.

I hope it works out. The pleasure is all mine.

Hi, I would find and remount the clips as they can cause a short if they rattle around with other components in the amp. They are stability clips.

@@EightiesNut thank you so much for answering my question but I saw the video and I put the clip where is belong and no luck the box is not working

If the MOSFET is blown the amp will not power on, that is basically it's protect mode.

More likely a MOSFET is bad. Your best bet is eBay.

Hi. I have ps28. Power spaker sistem Bose. I plug. Bud. Have a pop sound. Lake. Po po po pop.

I have the same problem with the knocking sound out of all speakers. I took a power surge from lightning nearby and blew the main unit and just tracked the sound to the subwoofer.

Hi, I am sorry I do not do any retail repair.

Do you know anyone who can repair? I have the same situation with Brian. PS28 subwoofer no power, checked the fuse and it’s not busted. Thanks