Hifonics BRUTUS BX1500D Problem

[mika111]

Ok..I´ll check this for you tomorrow............

 

[mika111]

Okay..now I have measured some things from the amp and here are the results:

HIP on it´s place:

op-amp pins 4-8 = 12,65VDC

HIP
1 = 12,08 11 = 9,69
2 = 12,66 12 = 9,70
3 = 11,93 13 = 0,00
4 = 0,00 14 = 0,00
5 = 8,76 15 = 12,68
6 = 6,50 16 = 12,66
7 = 5,10 17 = 0,00
8 = 5,20 18 = 0,00
9 = 5,20 19 = 9,69
10 = 12,11 20 = 9,69

Speaker output = 0,99VDC

One package of three ampFETs measures 2kOhms..others plus 300kOhms.

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Then, HIP out of it´s place:

op-amp pins 4-8 = 12,71VDC

HIP

1 = 12,34 11 = 0,00
2 = 12,73 12 = 5,55
3 = 0,00 13 = 0,00
4 = 0,00 14 = 0,00
5 = 0,00 15 = 12,76
6 = 6,51 16 = 12,76
7 = 6,57 17 = 0,00
8 = 0,00 18 = 0,00
9 = 0,00 19 = 6,31
10 = 12,38 20 = 0,00

Speaker output 0,000VDC, those ampFETs that before measured 2kOhms show now plus 300kOhms.

 

[Perry Babin]

You didn't say where each probe was placed when you measured the resistance on the FETs but if you had one of the 4 banks reading low with the IC in the circuit, it would appear that the IC has failed.

Check the IC out of the circuit. Resistance should read high between pins 11, 12, and 13 in all pin/probe combinations. Do the same for pins 18, 19 and 20.

 

[mika111]

Oh sorry, resistance was measured between G-D..yes it seems that something is killing the HIP. If I place a new HIP on it´s place it will die immediatly.

Resistance measures:

From board
11-12 = 300kOhm and slowly rising
12-13 = 300kOhm slowly rising
11-13 = 900kOhm

18-19 = 600kOhm
19-20 = 588kOhm
18-20 = 900kOhm

From HIP IC
11-12 = OL (first measuring was 0,02ohms but another started to rise and overlimit)
12-13 = OL
11-13 = OL

18-19 = OL
19-20 = OL (first measuring was 0,00 but with another measure it started to rise and overlimit)
18-20 = OL

That was a bit strange that at first they (11-12 and 19-20) seemed to be shorten but then I took another round and they were OL

 

[mika111]

When HIP is off the board..resistance between G-D is few hundred kOhms on those FETs and when I install HIP -> resistance drops to 0,00..anyhow HIP off the resistance between 18,19,20 pins is OL

So propably the HIP is dead (I have another one and it behaves the same), but something is breaking that HIP and I have no idea what would cause that.

 

[mika111]

HELP please I´m about to remove that f** HIP and do the FET drivin with normal transistors

 

[Perry Babin]

Does your meter actually read to two decimal places on ohms? Generally, the meter is set to diode-check when someone posts two decimal places.

The 4080 that you gave the readings on may be OK. If there were a short, it would be constant, even if you reversed the probes.

 

[mika111]

Yes..meter does show resistance in two desimals

Actually these measurements were measured with another multimeter (Mastech)..but anyway.

But for some reason the resistance on those FETs drop when I put that HIP on circuit :/

 

[mika111]

Maybe I´ll just throw this to WEEE....can´t figure out the cause of problems

 

[Perry Babin]

If you found that the resistance dropped with the 4080 in the circuit, it could have been due to charged capacitors in some part of the circuit allowing some part of the 4080 to latch. I'm assuming that you checked the resistance with no power applied.

 

[mika111]

Yes..no power applied, meter probes on FETs pins G-S (earlier was my mistake that G-D) -> HIP off = ohms few hundred kOhms, HIP on = ohms drop to near zero.

Maybe I´ll change those big capasitors also and lets see what happends

 

[Perry Babin]

Don't replace the capacitors (not unless you find a reason that they need to be replaced). Confirm that you read less than 0.1v across all of the capacitors in the amp and then re-check to see if that was causing you to read what appeared to be a short.

 

[mika111]

ok..lets do so. Perhaps it's never a bad idea to change those badcaps to something real, like Rubycon Than you for your help..it doesn't fit in my brains that measured differently the FETs are good and HIP is good, but together they're not. But let's recheck with caps zero voltage for sure.

 

[Perry Babin]

The only defective caps that I've seen in these amps are the ones shown in the attached image. They are used on the 12v side of the power supply. When they fail, they allow high frequency noise to leak into virtually every part of the amp.

 

[mika111]

Those are exactly the caps this amp is using

 

[Perry Babin]

Those had a very high failure rate and caused all sorts of problems. Connecting a single, large capacitor (1000uf or greater) across the B+ and ground terminals generally allowed the amp to function normally at low power when these were the problem. If you have a scope, you should see excessive high frequency noise on the B+ terminal of the amp (if these are defective).

 

[mika111]

Earlier I did that 'trick' and placed a 4700uF cap straight to B+ and GND -terminal..the amp showed a little lifesigns and tried to turn on (power led turned on green but it was like bumbing the current and led was sailing between bright and öö the other, not so bright). Secondly I added another capasitor (2x4700uF) to terminal and the amp did act like before -> power led red. So it didn't wake up anymore..maybe the HIP died at that first part :/ So..it seems that next reasonable thing to do, is change those larger caps to something better. And order a new HIP if this doesn't wake up with that capasitor change. I write with mobile phone and I cannot add enter

 

[Perry Babin]

I'm not sure if it's this amp but some of the hifonocs amps used terminals blocks that had plastic between the gold block and the circuit board. If these are loose, adding caps externally won't help as much as they should.

If you lock down a screwdriver or hex-key wrench in the block and then try to move it side to side, the block should not move. If it does, that's something else you will have to repair.

 

[mika111]

Thanks for all your help..I continue testing this amp at weekend.

Today is Finnish independence day, so it´s not a time to repair amps
But we´ll get back to business...

 

[mika111]

Power terminal seems to be sitting tightly...I soldered it betterly for just in case.

I think I´ll change those caps next.