Hi at all,
i am working on an Hifonics Brutus BRX 12000D digital mono amp with 6000 watts RMS. the amp works fine but when i opend the case
i found some bloated capacitors in the output filter section.i want to replace them,but i cant find
a distributor to order them.
the values are 68 uF,200V,BP.....BP should mean bipolar i think.
affected are 6 of this capacitors. i removed them and then i can see + and - symbols on the board.see the attached photos.
each 2 are connected with each other(in series) (minus and minus connected).
i know,to create one bipolar capacitor,i can use two poled electrolytic capacitors.
but why do they use two bipolar capacitors in series?
i am irritated by the label on the capacitors.is it real or a misdirection of the manufacturer to aggravate a repair?
can i replace them with normal poled electrolytic capacitors??
i am working on an Hifonics Brutus BRX 12000D digital mono amp with 6000 watts RMS. the amp works fine but when i opend the case
i found some bloated capacitors in the output filter section.i want to replace them,but i cant find
a distributor to order them.
the values are 68 uF,200V,BP.....BP should mean bipolar i think.
affected are 6 of this capacitors. i removed them and then i can see + and - symbols on the board.see the attached photos.
each 2 are connected with each other(in series) (minus and minus connected).
i know,to create one bipolar capacitor,i can use two poled electrolytic capacitors.
but why do they use two bipolar capacitors in series?
i am irritated by the label on the capacitors.is it real or a misdirection of the manufacturer to aggravate a repair?
can i replace them with normal poled electrolytic capacitors??
Attachments
Some more recommendations:
1 - Find the capacitor model with the highest (ripple current)^2*(rated life in hours) factor (105C assumed). Some candidate models are listed here: https://www.digikey.es/products/en/...wproducts=0&quantity=&ptm=0&fid=0&pageSize=25
2 - Find some common use internal voltage rail, like -15V w.r.t. amplifier outputs, and add 100k resistors from that negative voltage to the junction of negative terminals, so that the polar capacitors get some bias voltage during operation.
All these LF class D amplifiers using BP electrolytic capacitors in output filter are irresponsibly designed, these electrolytic output capacitors always fail like that after months or years of use. These "hype era" car audio amplifiers are intended to last long only when cranked up momentarily to show it to others, and used at low volume rest of the time.
1 - Find the capacitor model with the highest (ripple current)^2*(rated life in hours) factor (105C assumed). Some candidate models are listed here: https://www.digikey.es/products/en/...wproducts=0&quantity=&ptm=0&fid=0&pageSize=25
2 - Find some common use internal voltage rail, like -15V w.r.t. amplifier outputs, and add 100k resistors from that negative voltage to the junction of negative terminals, so that the polar capacitors get some bias voltage during operation.
All these LF class D amplifiers using BP electrolytic capacitors in output filter are irresponsibly designed, these electrolytic output capacitors always fail like that after months or years of use. These "hype era" car audio amplifiers are intended to last long only when cranked up momentarily to show it to others, and used at low volume rest of the time.
what value of ripple current is more important,
Ripple Current - Low Frequency or
Ripple Current - High Frequency ?
the dimensions of my unsoldered capacitors are 18mm x 31mm.
to maintain these dimension,can i use a capacitor with 450V ?
are bipolar capacitors bigger then normal
capacitors with same values?
i am not really sure if that capacitor shown on the photo,is really a bipolar.maybe it is relabeled by the manufacturer of the amp???
Ripple Current - Low Frequency or
Ripple Current - High Frequency ?
the dimensions of my unsoldered capacitors are 18mm x 31mm.
to maintain these dimension,can i use a capacitor with 450V ?
are bipolar capacitors bigger then normal
capacitors with same values?
i am not really sure if that capacitor shown on the photo,is really a bipolar.maybe it is relabeled by the manufacturer of the amp???
Both ripple current values are important. The LF value is for the LF audio signal, the HF value es for class D carrier attenuation.
Do not use 450V capacitors, these have lower ripple ratings, part selection is more important than lead spacing in this case, the amplifier does not use such a high voltage as 450V, 200V should be OK, even less, this can be checked by measuring the rail voltages of the amplifier. 6000W rms on 2 ohms are about +/-160V peak (single 160V rail feeding H bridge), about +/-110V peak if 6000W/2r is peak rating and rms rating is 3000W.
Do not use 450V capacitors, these have lower ripple ratings, part selection is more important than lead spacing in this case, the amplifier does not use such a high voltage as 450V, 200V should be OK, even less, this can be checked by measuring the rail voltages of the amplifier. 6000W rms on 2 ohms are about +/-160V peak (single 160V rail feeding H bridge), about +/-110V peak if 6000W/2r is peak rating and rms rating is 3000W.
Recommended reading for understanding part type replacement and industrial production:
Which diode specifications for equivalence?
Which diode specifications for equivalence?
As Eva mentioned, the use of electrolytics in output filters is not proper use of parts, but even the big ones like Harman are doing it. Friend of mine blew a subwoofer from Harman, cause was electrolytic in output filter.
Question to our great class D expert: Eva, why do they use such large values in the output filter (Harman had a 22 uF)? Is that to get by with a smaller sized output inductor, thus saving even more?
Question to our great class D expert: Eva, why do they use such large values in the output filter (Harman had a 22 uF)? Is that to get by with a smaller sized output inductor, thus saving even more?
SUB-TS2BQ Harman/Kardon powered subwoofer, apparently was quite expensive. Cheap phenolic PCB looks toasted in some areas too. They really skimped on parts quality and probably put too much resources into a black glossy piano finish. Very deceptive difference between inside and outside quality.
These are first generation class D amplifiers, the designers were copying and were under pressure for releasing something quickly, they did not have proper understanding of what they were doing. Electrolytic class D output capacitors are still used in Chinese 3rd class amplifiers, but because they are still copying 10+yr old 1st generation, a kind of product to avoid.
i built in the new capacitors now.
i checked with 100 Hz input signal but without load.
i increased the input signal until i could see the clipping on my scope.
the capacitors become a little bit warm,should work........
i checked with 100 Hz input signal but without load.
i increased the input signal until i could see the clipping on my scope.
the capacitors become a little bit warm,should work........
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