Repair a KRK 10s Subwoofer - parts id

Hi GromTag,

I had a few minutes today to take the sub-apart to inspect and take pics before too long.

I actually found where the next issues cropped up. In the area of the two big resistors (you had me check this area before).

Here's the location (old pic):



And now the resistors that look blown or corroded moreso than before:



Above you can see that it got hot on there because before it was gobbed over with black junk (now it's melted off).



This big white resistor is loose, and I think it's in need of removal/inspection.. LOL



Above is the 2nd white resistor.. Looks like it might have been next to melt.. Not so sure...



The old area that I replaced all the parts on, looks good:



So there's the last bit of imagry after Defcon 5... haha

If that is corrosion under the glue at those parts, then the whole board might have issues that can continue even with repairs (unless the whole board is refit). The heated part looks to be a glass diode possibly another IN4148 next to the large resistor. D707? might be an Z for Zener type.

GromTag said:

If that is corrosion under the glue at those parts, then the whole board might have issues that can continue even with repairs (unless the whole board is refit). The heated part looks to be a glass diode possibly another IN4148 next to the large resistor. D707? might be an Z for Zener type.

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Yes, I understand that this could be a fruitless excercise now. Was interesting and I picked up some good tips along by the way, thanks!

I have no sound comming out of my sub krk 10S took everything apart and everything looks fine with no issues
gets power and subwoofer is fine whats the first thing i should check with my volt meter?

i can tell you something to check without using the meter. start with the sub powered off and no signal cables connected. remove the grill or grill cloth if there is one. and begin tapping on the woofer cone near the middle of the speaker. tapping on the woofer should sound like "thump... thump...thump"... while tapping on the cone, turn on the subwoofer power, and the thump you hear should change it's sound (usually the thump goes up in pitch). if the sound changed, the amplifier output stage is good, and the speaker wires from the amp to the woofer are ok. if the sound of thumping doesn't change, either a speaker wire has got disconnected inside, or the amp is bad. if the amp works right, check the preamp/filter section . if the sound doesn't change, check the wiring to the woofer, check to see that the tinsel wires connecting the voice coil to the terminal strip on the woofer basket have continuity. test the woofer with an ohmmeter (with at least one wire on the woofer disconnected). if there's continuity in the woofer, and the wires are ok, look at the amplifier PCB. check any fuses on the amp pcb.

if the problem is in the preamp stage, reconnect an audio source and power the sub back up with the woofer connected, and the amp and preamp outside the box, you will want to check for signal on the Level (Volume or Gain) control on the center terminal. you will need an oscilloscope or a audible signal tracer

Hello, my name is Carlos, I'm from Brazil.
Does anyone know the value of the resistor rh701
, what is under the board.
I am following this post, and I am very grateful for all the information, I have problem in the same sub, my English is very bad. If I can help you count on me

WIZARD1325 said:

I have no sound comming out of my sub krk 10S took everything apart and everything looks fine with no issues
gets power and subwoofer is fine whats the first thing i should check with my volt meter?

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The led in the logo are green or red?

kadro said:

Does anyone know the value of the resistor rh701

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No idea on what 'value' it might be, but it doesn't look like it's a resistor - I presume it's actually a thermistor.

Nigel Goodwin said:

No idea on what 'value' it might be, but it doesn't look like it's a resistor - I presume it's actually a thermistor.

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Yes, but what value?

kadro said:

Yes, but what value?

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Thermistors don't have 'values' they have 'model numbers' like transistors do - you need the EXACT same one as fitted originally (assuming it's faulty?). I'm assuming it's for temperature compensation, and the wrong type will most probably blow the amplifier.

I don't know if this are bad. I can not read the model number, and i do not have the service manual.

I have the following problem, my sub stopped working after getting very hot, I opened it and changed some capacitors that were bad, I changed the output transistors and their drivers. taking the output signal before the relay, apparently this is correct, without DC, but the protection does not trigger the relay