B&W 801 S2 Troubles (AKA, I'm flummoxed)

So my 801 Series 2's are acting up. More specifically, I lost all sound to my one of my speakers.

It started with no woofer activity for a day or so (Wednesday-ish), and then proceeded to no sound from any of the drivers. I had originally suspected an old, finicky preamp that I had been playing with, so I dismissed it and figured I would get around to trouble shooting this weekend. However, when I plugged in my other pre, nothin' from the right speaker. Switched up the interconnects...nothin'. Switched up the channel wires at the amplifier...nothin'. The lack of sound followed the trouble speaker the whole way. Crap.

Tested the speaker at the terminals using the multimeter and got nothing (biamp terminals are jumpered on the crossover). No reading whatsoever. Hm. Weird. Have been pulling the speaker apart all morning, testing drivers and everything seems to be working well:
-woofer is happy at ~6ohms
-head unit seems to be pretty happy as well; the positive (3) and negative (1) terminals on the balanced cable interconnect reads out to 12.1ohms on my multimeter...identical to the other head unit on the functioning speaker.

So I think I'm looking at a crossover problem. I pulled the bottom off the speaker to reveal the crossover, and pretty much pooped myself. And that's about as far as I've gotten. Looking for pointers, help, suggestions and general guidance on this, as I think I'm over my head with respect to technical capabilities...:sigh:

Gratuitous photos of course...

I'd start by looking at the protection circuit, those relays to be more precise. See if you can pop the covers off and get a look at the connections.

By relays, do you mean the mustard-colored plastic boxes?

The blue boxes that say Guardian Electric on them. You should be able to gently pry those covers off... Get some emery cloth and rub it between the contacts inside. If it helps the situation, look at finding some replacements as cleaning them is generally temporary.

Thank very much, HyKlas. I'll give it a try and report back...

Haven't been able to get the tops off the relays...I feel like I'm going to break something if i force it too much. any pointers?

A bit difficult with them on the board but it can be done. I use a little 90° pick and a pocket screwdriver... If you have soldering stuff, which I'm assuming not, you could always pull them from the board to disassemble.

Another thing to look at is all of the solder joints on the back side of the board. Google "dry solder joint" to get an idea of what bad ones look like if you're not sure.

Thanks again, HyKlas. I do have a decent soldering iron, so I may try to pull them off the board. I did a quick once over looking for cold joints, but didn't see any. I'll get the jeweler's loop out and take a closer look...

HyKlas said:

A bit difficult with them on the board but it can be done. I use a little 90° pick and a pocket screwdriver... If you have soldering stuff, which I'm assuming not, you could always pull them from the board to disassemble.

Another thing to look at is all of the solder joints on the back side of the board. Google "dry solder joint" to get an idea of what bad ones look like if you're not sure.

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I may be wrong, but a lot of people recommend completely bypassing these relays.

I just mentioned cold joints since for one, it'll cause that and secondly, I've repaired a half dozen of them at work today so it seemed like a trend. Especially considering I do automotive work, it's pretty rare I get to pull out the soldering iron and go digging in to relay packs and control modules...

nclh77 said:

I may be wrong, but a lot of people recommend completely bypassing these relays.

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Yes, and in subsequent versions, they were removed.

Most likely that protection circuit kicked in, dig it out or bypass it, you don't need that device if you have a cool amp.

As an owner of an 802 S2, interesting to me that the 801 S2 has an LED by the bass port. Does that light on big transients? With the APOC out of the x-over, let's see if it will now work. Good luck!

Running a bryston 4bst, so maybe I'll try the bypass on the trouble speaker

Those are molded relays , the tops do not come off , pull off the board and replace them with new one or jumper wires , your call .

Is there a step-by-step series of instructions for bypassing the APOC? I'm up for the challenge, but want to make sure I'm doing exactly what I intend to do (instead of removing important components, for example). I've taken a look at the Van Alstine mods (http://www.audiokarma.org/forums/showthread.php?t=512873) and may attempt them at some point, but I'd like to try and get things back up and running first. So, anybody have the specifics steps for bypassing the APOC?

Mrv8q said:

As an owner of an 802 S2, interesting to me that the 801 S2 has an LED by the bass port. Does that light on big transients? With the APOC out of the x-over, let's see if it will now work. Good luck!

Click to expand...

I've actually never had them light up...These speakers have been driven by a Pioneer Spec 2, a pair of Bryston 2b's bridged for mono and now a Bryston 4bst. I've played them loud and soft and never had the APOC tripped (and the LED flicker on).

bustedguild said:

Is there a step-by-step series of instructions for bypassing the APOC? I'm up for the challenge, but want to make sure I'm doing exactly what I intend to do (instead of removing important components, for example). I've taken a look at the Van Alstine mods (http://www.audiokarma.org/forums/showthread.php?t=512873) and may attempt them at some point, but I'd like to try and get things back up and running first. So, anybody have the specifics steps for bypassing the APOC?

Click to expand...

There used to be one on the web years ago. It may still exist somewhere. It isn't that difficult to do as I recall.

edwyun said:

http://www.audiokarma.org/forums/showthread.php?t=610483

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Hm. So it looks to be as simple as lifting the legs on the black diodes D3,D4 and D8... is there any reason to clip the jumpers as indicated in the Van Alstine mods as well?