Hifonics BXI 2610D schematic

Jamie85

Member
2013-02-20 2:29 am
All of the resistors have the outer plastic burned off of them except two. Those two are discolored and hard to make out for sure. I measure about 6.4 ohms on all except the 2 of them in question , those are 20 and 28 ohms. The two that aren't as burned look like (brown black black gold) and (yellow brown black gold) but they measure ~6.4 ohms so I'm not sure about the colors. There are some (brown black black gold) on the output side of the amp. I figured those to be 10 ohms if I'm right. Thank you.
 

Jamie85

Member
2013-02-20 2:29 am
Thank you for your help Perry Babin, I really appreciate it! I have also been talking to a repair shop for hifonics and they said the resistors should be all the same at 47 ohms and that all of the Fets are probably bad even if they test ok. Do you agree? I'll just replace them all cuz they were only $2.50 a piece. If I have this much issues with the fet area should I check anything else before turning the amp back on? Thank you
 
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Jamie85

Member
2013-02-20 2:29 am
I asked him what else i should check and he said:

"also check the gate driver transistors in the middle of the PCB between the
transformers.
you should check the gate drive with a scope to the power FET's before you
actually install new ones."

What does he mean scope? And could you please tell me how to do this? Thank you.
 
I asked for the circuit board designations because the description that you gave was too vague. With those, I could have told you what you needed to know.

If you haven't done so, read ALL of the basic amp repair page (link in sig line below). it will save a lot of time.

The gate drivers are Q7, 7a, 8 and 8a. It's fairly common for Q8 and 8a to fail when the power supply FETs fail.

He meant check the signals with an oscilloscope.
 

Jamie85

Member
2013-02-20 2:29 am
Ok I read the amp repair page. I removed Q7A and I'm trying to test it but I can't find a data sheet with c3228 on it. Is it easier to test it in the circuit?

I tested the transistor and I'm still not sure if they're ok. I may have been able to figure it out if I could find the right data sheet. Could you please tell me if this sounds ok for measurements outside of circuit?

Pin 1-2 OL
Pin 2-1 OL

Pin1-3 OL
Pin 3-1 a seemingly descending 21.4m ohms (it starts at over 22m and slows around 21.4m

Pin 2-3 OL
Pin 3-2 another descending number ending at about 19.5m ohms

Hopefully this is enough information.

Thanks again for your help
 

Jamie85

Member
2013-02-20 2:29 am
Ok, I tried to click on them but nothing came up on the screen from my phone and I didn't have access to a computer. I will check the links and figure it out. Sorry to ask too much, I do want to learn how to fix amps but I've never had to trace a problem so far. (in only 5 other amps)
 

Jamie85

Member
2013-02-20 2:29 am
Ok so I've read the transistor test and the data sheets. I'm a little lost on the data sheet but I can identify the base collector and emitter and see the tolerance for the base to emitter legs. There isn't a diagram of the inside but I think the transistor is working properly. When I measure from the base to the collector or emitter I get 0.58v. When I measure between any other combination I get OL. But when I connect the base to the emitter with the red lead and measure the collector with the black lead I get 0.58v. When I connect the base to the collector and measure the emitter I get 0.50v which is still in tolerance I think. Did I check it right? How do these numbers look to you? Thank you
 

Jamie85

Member
2013-02-20 2:29 am
I checked the C3228 and A1275 transistors and one of them showed 0 resistance so I replaced them all with BD139 and BD140 ones. The amp now turns on and doesn't start smoking, which is a big improvement, but there is no sound. I checked the speaker terminals and there is almost no voltage at the speakers. 0.004v in negative and 0.020v in positive. I checked using the main ground terminal, hope that is correct. I checked the IC's on the small vertical board above c220a and I get zero resistance from pins 11-12 on IC1. I've checked some voltages and I didn't see anything jump out as suspicious. Do you have any ideas where I should look?

Note: The saldering iron I was using wasn't hot enough to remove from this board properly, I think because it's too thick, so I lost a few of the solder rings on the power side. I bought a new iron now and I inspected the circuit tracks and I think all of the pins are connected to the board where they need to be. The amp powers up and doesn't go into protect so I'm guessing it's ok, I just thought it may be useful to tell you.
 

Jamie85

Member
2013-02-20 2:29 am
Ok, Thank you. I'll concentrate on the copper side next time. I'm still learning alot but I'm enjoying learning.

I've only repaired 6 other amps but they have gone smootly but this one is being a PIA it's my fault though. I read on your website that you need to be careful when the amp is powered up and you check voltages. Somehow I wasn't careful enough and I made a mistake that I'm learning to never let happen again. I crossed the lead with R22 and 22 (the end pin on the vertical board) and there was a spark, then the amp went into protect. I'm really sorry Perry, I appreciate your help a ton and now I made a mess of this one.

I'll tell you what I checked:

R22, C54, Q23 and Q21 out of board, Q16 Q20 Q22 in board, on the other side of the board the transistor opposite Q23 out of board because they were connected, continuity of circuit board connections around spark, resoldered pins on bottom of board. After doing all of this I reinstalled the board and the amp still went into protect. I then took out the board again so I could keep testing.

Could you please help me with what I should check next?

I was trying to check voltages on different spots to see what was working properly and what wasn't. The output fets seemed ok but he speakers had barely any voltage so I was looking for a possible cause.

Here are some pics of my disaster.
 

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