KLH Bassbite II Subwoofer works, satellite speaker channels do not

[Mrx3750]

I found a KLH Bassbite II in the trash last night. I figured it would either work, or the sub woofer itself would be blown. It turns out that the sub itself works fine. The four satellite channels do not however.

I opened it up, and I think I've found the problem. R 52 and possibly R 53 look like they're fried. (see the attached pic) However I'm not sure what to replace them with as I'm not very good at reading color bands, and R53 is a lost cause anyway. (tested at several megaohms, in circuit, so my guess is it's open)

I'm thinking these are low ohm resistors put in place as a sort of failsafe if the satellite speakers blew or shorted. Since the sub still works, I'm thinking the amplifier itself is fine.

[budm]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Another brown glue problem, if it is the same resistor next to the burnt out one, the one next to it is 1 Ohm resistor (Brown/black/black). You need to remove those glues, they are corrosive and conductive.

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Okay. a 1 ohm resistor. That supports my theory of it being a failsafe.

I probed the glue with my multimeter probes and got no conductivity, however it is very black in spots so I'll take your word for it.

What's the wattage of those 1 ohm resistors? I'm guessing 2 watt?

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Okay I got the resistors out. The one that I can read reads as brown, black, black, gold, gold. That comes out to 10 ohms at 5% tolerance, and my ohm meter reads 10 ohms on it.

The second resistor is going to be an issue though. The ohm meter reads exactly 5 mega ohms, and it's too fried to get a color band reading off it. Its position in the circuit makes me think it's another 10 ohm, but I'm not certain, and I'm still unsure of the wattage.

In the meantime I'm removing as much of the glue as I can.

[budm]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Ah, I thought the 4th one is Silver. Can you post the pictures of the bottom side of the board?

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Okay got a pic of the bottom board as requested, and a pic of the top as it looks right now.

[budm]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Are those big square solder pads (4) connected to some kind of speaker terminals?

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Yes. There's a board with the four satellite speaker terminals that solders onto it. had to remove it to get the resistors out.

[budm]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

So each resistor is in series with the speaker, so if the resistor has open circuit, you will not get the sound then.

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Makes sense. I plan to hit up Radio Shack tomorrow and see if I can get two new 10 ohm resistors. Once I get those in, I'll test and see if it works.

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

I can't believe that I can't find on Google how to determine the wattage of a resistor by physical size. This should be common knowledge!

So the resistors that I removed have a physical size of 9/16 of an inch, and are about 1/4 inch long and 3/16 in diameter.

I got some 1 watt resistors from Radio Shack that are metal oxide resistors. The diameter is the same, but they're only a half inch long. And I can't find a useful resistor size chart on Google, just a bunch of sites telling me to use a bunch of mathematical formulas to determine wattage. No! I just want to know what the wattage is of the resistors I pulled out.

[budm]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

MOX (Metal Oxide) 2Watts should be good so it can handle more power.
See typical size here:
https://cdn.badcaps-static.com/pdfs/...d10f181b0f.pdf

http://www.mouser.com/ProductDetail/...fPq37PGVSoo%3d

http://www.mouser.com/ProductDetail/...IpzKTuv0lEg%3d

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Well, the 1 watts are in place for now. I figure they'll do just for quick testing.

Now I'm getting a 60 Hz hum through the subwoofer. However music still plays through it. Satellite channels are still blown. Really wish I could find a model number so I could track down a service manual.

Edit: Testing in circuit tells me that R54, R42 and R41 are also blown. Looks like I'll need to hit up a real electronics store.

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Well, I've been searching for anything I can find on this subwoofer, and I think the model is OUTLET-BB-II

There is like almost zero technical or service information. I can't even find an owners manual, and the KLH website is under construction.

The ironic thing is that I bet if I replaced the board, the damn thing would work peachy keen.

Anyway I do have a question about diodes. There are two ziener diodes in the blackened area that I'm pretty sure are fried as well. As far as I know, a diode is a diode and there's nothing important apart from how much current they can handle. Can I replace these little ziener diodes with, say a couple bigger black diodes from a power supply?

[momaka]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Anyway I do have a question about diodes. There are two ziener diodes in the blackened area that I'm pretty sure are fried as well. As far as I know, a diode is a diode and there's nothing important apart from how much current they can handle. Can I replace these little ziener diodes with, say a couple bigger black diodes from a power supply?

Yeah, I was going to say, those Zener diodes do look pretty burnt up. Unfortunately, no, you can't just replace them with any diode. The replacement needs to be a Zener diode too, and moreover, you need to match the Zener voltage.

The difference between a Zener diode and a regular diode is that a Zener diodes can be used to repetitively conduct small currents in the reverse direction, and this is only once the reverse voltage on them has gone higher than their rated reverse voltage. So for example, if you have a 5.1V zener diode connected with Cathode to the positive side of a voltage source and the Anode to the negative of the source, then the diode will not conduct until the voltage source reaches 5.1V or higher. If the Zener diode was a 12V Zener diode, then the diode would conduct at 12V.

I don't remember too well, but Radio Shack may have some of the more standard Zener diodes. However, first we need to determine what those Zener diodes do.

Any chance you can read the numbers off of IC1? Also, there are 5 wires coming to this board. Can you trace what they are connected two? I would guess two are for L/R channels, 1 ground, 1 VCC, and not sure what the 5th one would be. Better pictures (with better light) will also help.

Also, check if the speakers are still alright if you haven't done so already. (i.e. check their resistance with a multimeter). Post what values you get for that.

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

The satellite speakers are fine. Tested those with another source.

It turns out that the resistors in the blackened area seem to be fine, though I just finished replacing them. No change. There were two bad 22uf@25 volt capacitors in the blackened area which I replaced, along with a marginal 4.7@50 volt.

I believe the diodes are okay. I tested one out of circuit, and it tested fine. Also the electronics shop guy (from a real electronics store) said they didn't look smoked.

So far I've replaced all the resistors in the blackened area, and those three bad caps. Still no change.

Those 5 wires lead to the power supply board, which has an amplifier IC. I don't know if that IC is just for the sub or the sub and satellites.

The numbers on the IC (the long one on the board I'm working on) read LM32 w98019841 I can't find a match by googling it. No idea what it does.

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Correction! It's an LM324N IC

And how about that it's a quad amplifier IC.

And I had trouble reading the lettering because it's burnt off. What do you wanna bet that IC is bad.

[momaka]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Possibly.
Download the data sheet and check if any of its inputs and outputs are shorted.

Those 5 wires lead to the power supply board, which has an amplifier IC. I don't know if that IC is just for the sub or the sub and satellites.

Google the numbers on that IC then and see if any of the wires from this board (the one with the supposedly burned resistors) are connected to that IC.

[Mrx3750]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

Well, took the IC out and tested it. Infinite ohms from input to output pins, and infinite ohms from GND to VCC. I have a feeling it's fried.

So I ordered a replacement off of eBay.

[momaka]

Re: KLH Bassbite II Subwoofer works, satellite speaker channels do not

That seems normal to me, but we will see when you get the new one and try it.