CurtPalme.com Home Theater Forum

[ecrabb]

OK, guys - this may be beyond me, even with expert help. It's a good friend's piece though, and his theater has no subs right now, so I'd love to be able to get it working for him. He has two with the same failure mode, so if it's not too tricky to find the problem with this one, then I get a double-whammy.

Here's a link:
http://www.keiga.com.tw/products_kgnd5250.html
http://www.madisound.com/manufacturers/keiga/

Here are a some photos of one on Canuck Audio Mart thats pretty much identical:
http://www.canuckaudiomart.com/details/649094411-keiga_kgnd5250au01_subwoofer_amplifier/images/662292/

The thing is really heavy. It's got a big toroidal transformer and a 10000µF cap almost as big as a pop can. I think it's in the $400-500 ballpark.

If I switch auto-on to 'off', and turn on the main switch, the light goes from red (standby) to green (on), and along with it a good solenoid click and nice bit of transformer hum, so it seems the PSU is working properly. The outputs however are deader than a doornail.

There's a sticker on the output wires that reads, "Shorting of the speaker wires while the amplifier is on will result in failure of the Ice Power Module. This is an expensive repair!!!"

I'm sure the amp was never abused, and of course it was never taken apart until after the amp started working, so the only way the outputs could have been shorted is if the voice coils shorted. An amp module is with me here and the subs are a day's drive away at the moment.

These certainly weren't cheap amp modules, but are they not easily repairable? I think I remember Curt saying the Ice amps were extremely difficult to diagnose and/or repair.

I'm guessing they're only 4-5 years old.

Thanks for any input or guidance.

Regards,
SC

[ecrabb]

Couple of other things:

There is a little tiny bit of 60hz hum from the mid/bass driver on a speaker connected to the outputs when the amp is on. It's independent of the amp's gain setting or input connections.

If the auto-on circuit is set to 'on' (meaning auto-on), the amp does power-on (with the master power switch) in standby mode. As soon as I plug in a line-level cord, the amp powers on, so it at least appears the input side of the amp is working. But…

If I connect a line-level source to the line-in input, and connect an amp w/speaker to the line-out, it's dead. So, maybe it is the line-level circuit before the amp.

SC

[ecrabb]

Last thing, and then I have no idea... Only about 2.5mV worth of DC offset on the output. It dissipates to about .6mV when mains power is removed.

SC

[stridsvognen]

Quite sure its the self destruct that was activated. Seems to be standard instaled in many Class D amps.

Try call a repair shop that works with those amps, sure they know just what parts, or boards you need to replace.

If its B&O ICE power modules just replace the amp module, some of them are known to be bad. I know B&W used the B&O ICE power modules and had to change a lot of them.

http://www.icepower.bang-olufsen.com/en/company/history/

[beun]

Do you have a scope? When the class-D output stage is running you should see high frequency ripple at the output. When you don't the output is not switching.

[El Duderino]

ICE was developed and marketed by Dr. Karsten Nielsen in a joint venture with Bang & Olufsen, so yea, if it's ICE, it's likely B&O

You can ohm out the voice coil to see if it's shorted. Also connect it to another amp to make sure the woofer is good. If the woofers are good, then it's unlikely it got smoked due to a bad driver. I'd be suspicious of leaky electrolytic caps then. Not the big reservoir cap. If you don't have a ESR C meter or I/V tracer to check the integrity of the El caps, look for any that appear swollen or pregnant, although they can look fine and still be leaky as hell.

If the ICE module is toast, I'd question the value of replacing it unless you can find it cheap and easy. A quick glance says they are neither. I wouldn't put $200 and hours of time into a $500 device.

Hey, if the drivers are good, buy a used higher power AVR for $50 and put it on top. You can keep both of them out of the land-fill for a few more years.

[macgyver655]

Hark, if only there be a visitor who was familiar with slinging ice on a weekly basis.

But alas, this inquiry has been placed in an improper location, where one must enter a series of letters or numbers, just to be able to swim in the murky and vial waters, amongst the debris, waste and scum, just for a glimpse of what could be a mere trinket of substance. A trinket in which many may never see or to offer some possible hope that an objective may be revealed.

And so , as it sinks to the bottom of the murky water, so does the anticipation of any successful outcome.........

[ecrabb]

Oh, great ice slinger who speaks in riddles... Would ye be satisfied now that the inquiry has been moved to a shallower, less murky location, one which doesn't require a series of letters or numbers? Please now could you edify me with even a shard of your ice-slinging knowledge?



SC

[macgyver655]

I just got a call and have to run out so I will respond when I return.

[macgyver655]

So, lets see where we are at. I could not find a schematic for this particular make so we will have to assume a few things and see where it takes us.

First off, since it's a 2 channel amp, chances of both channels being blown are slim. If fact any individual channel component is also slim. It needs to be something that pertains to both channels. The line in/line out issue would also pertain to this.

So what does that leave? It leaves an ic. But not necessarily an ic itself but possibly a line power that is down. If an ic handles a signal of both channels and looses its power then you will have nothing.

So, look on those boards where the wires connect and see if they are marked for voltages. If they are not, then you will have to examine all boards carefully for any voltage regulators and get the part numbers off of them.

Also check all fuses, including looking for pico style and/or surface mount ones or even ICP's.

Happy hunting.

[El Duderino]

[macgyver655]

[El Duderino]

[stridsvognen]

Do it look like any of the ones in the links..?

http://www.icepower.bang-olufsen.com/files/solutions/icepower250asx2_datasheet_1_1.pdf

http://www.icepower.bang-olufsen.com/en/solutions/speaker/

http://www.icepower.bang-olufsen.com/en/solutions/speaker/ASP_SERIES

[stridsvognen]

From the links data and pictures, ill guess this is the one.

http://www.icepower.bang-olufsen.com/files/solutions/icepower500adata.pdf

[Curt Palme]

Just my $.02. If the amps are anything close to what strids posted in his first link... GOOD LUCK fixing that! Switching amps are insanely complex. That's something that I personally would walk away from. If it's beyond your ability to troubleshoot, either send it to Mac if he wants to take a stab at it, or just power the subs with a separate 200 watt per channel amp, and bring the subwoofer wires out to the back of the unit to connect to directly.

[Curt Palme]

Just my $.02. If the amps are anything close to what strids posted in his first link... GOOD LUCK fixing that! Switching amps are insanely complex. That's something that I personally would walk away from. If it's beyond your ability to troubleshoot, either send it to Mac if he wants to take a stab at it, or just power the subs with a separate 200 watt per channel amp, and bring the subwoofer wires out to the back of the unit to connect to directly.

[macgyver655]

[macgyver655]

[macgyver655]

[stridsvognen]