Energy s10.3 subwoofer issues

[soulraver]

Hey guys I am attempting my first fix of a powered amplifier, I was hoping to get some input on diagnosing the issue. The amp blew a fuse, and continues to blow fuses anytime i put one in. I unplugged the PT output wires, put a fresh fuse in.. what type of testing should i do? Output voltage from the PT is 30v. The sub has a Off / Auto / On switch, even when in the off position the fuse blows, visually everything on the board looks good, no leaking caps, burnt resistors, etc. I am somewhat new to all this so i apologize for that

[budm]

Re: Energy s10.3 subwoofer issues

Post good clear pictures of the boards, inside/outside the unit to see how it is wired, etc. will be a good start.

[soulraver]

Re: Energy s10.3 subwoofer issues

No problem, here are few shots of the amp. There is a second board under this one that is the high pass crossover. I unplugged it to rule it out and the fuse still blows. Let me know if you need any close up pictures or anything else. Thank you for the quick reply
(There is two very large heat sinks connected to both sides of the board)

[budm]

Re: Energy s10.3 subwoofer issues

OK, please post the straight shot of the bottom side of the board so I can show you where to check the bridge rectifier and the output device to see if they are shorted out or not.

[soulraver]

Re: Energy s10.3 subwoofer issues

Sure here it is, bottom of picture is the side of the fuse from the top

[budm]

Re: Energy s10.3 subwoofer issues

OK, disconnect the secondary transformer wires from the board, then take the resistance reading on the following points (we are not using Diode mode for testing because we are looking for low resistance readings due to shorted out component):
Bridge rectifier:
Pin 1 & 2 = xxx Ohms
Pin 1 & 3 = xxx Ohms
Pin 1 & 4 = xxx Ohms
Pin 2 & 3 = xxx Ohms
Pin 2 & 4 = xxx Ohms
Pin 3 & 4 = xxx Ohms

Get the P/N of the devices A and B

[retiredcaps]

Re: Energy s10.3 subwoofer issues

Made in Canada!!!

Some of the glue around the big capacitors are starting to turn color which may suggest it will turn conductive in the future.

[budm]

Re: Energy s10.3 subwoofer issues

Yes, the glue will have to be removed as well.

[soulraver]

Re: Energy s10.3 subwoofer issues

Awesome! I have finals this week so it will have to wait until Friday, but thank you so much I will reply back when i get all the readings! Thank you.

[soulraver]

Re: Energy s10.3 subwoofer issues

Okay i finally got around to getting some readings

1 & 2 = 110k
1 & 3 = 104k
1 & 4 = 2.0
2 & 3 = 2.8
2 & 4 = 15.5k
3 & 4 = 15.5k

Iv never done a p/n test, not sure what exactly i should be doing on that on? is that the same as testing a diode?

[budm]

Re: Energy s10.3 subwoofer issues

1 & 4 = 2.0
2 & 3 = 2.8
Are they 2 Ohms and 2.8 Ohms? If they are in Ohms, you do have shorted circuit.

[retiredcaps]

Re: Energy s10.3 subwoofer issues

1 & 4 = 2.0
2 & 3 = 2.8
Are they 2 Ohms and 2.8 Ohms? If they are in Ohms, you do have shorted circuit.

@soulraver. You should also desolder to verify the above readings. If they are in the 2.0 ohm range, then it is definitely shorted.

[soulraver]

Re: Energy s10.3 subwoofer issues

Okay guys i followed your advice and removed the bridge rectifier (very much so a pain to remove), the ohm readings are all the same on the points except where i was getting 2.0 ohms on 1&4 and 2&3, are now reading infinite ohms, guessing open circuit.. on the board i tested where 1&4 solder on the board and it is 2.0 ohm's still, at 2&3 it is infinite..

[retiredcaps]

Re: Energy s10.3 subwoofer issues

Okay guys i followed your advice and removed the bridge rectifier (very much so a pain to remove), the ohm readings are all the same on the points except where i was getting 2.0 ohms on 1&4 and 2&3, are now reading infinite ohms, guessing open circuit..

So the bridge rectifier is good since it measures not shorted out of circuit.

on the board i tested where 1&4 solder on the board and it is 2.0 ohm's still, at 2&3 it is infinite..

Something is shorted between 1 and 4 then. Spatial mapping is not a skill I have so someone else will have to suggest possible shorted candidates. I usually test the diodes, power transistors and the larger filter cap (after it has been discharged) for shorts.

[budm]

Re: Energy s10.3 subwoofer issues

At post 6 I requested for the P/N of those two devices A and B. they need to be checked for shorts when we find the data sheet for them.

[soulraver]

Re: Energy s10.3 subwoofer issues

Yeah I saw the P/N request, but I am somewhat new to this and trying to learn, so I am unsure what P/N testing is? I know devices A and B are output devices, am i testing the resistance of each device using the + - points you have pointed out?

[budm]

Re: Energy s10.3 subwoofer issues

I need the P/N of the devices to look up the spec sheet so we can check the resistance reading of the devices to see if they are shorted out or not.
Right now I do not know if the devices are NPN and PNP transistors, or they are ICs, or MOSFETs.

[soulraver]

Re: Energy s10.3 subwoofer issues

Oh i apologize its been a long week, P/N's are A - IRF640 I↓R 639p and B is the same

[retiredcaps]

Re: Energy s10.3 subwoofer issues

P/N's are A - IRF640 I↓R 639p and B is the same

IRF640 is your power mosfet.



Test all three pin combinations for shorts. That is, G-D, D-S and G-S. Any reading less than 30 ohms warrants desoldering the component and verification out of circuit.

[soulraver]

Re: Energy s10.3 subwoofer issues

Hey guys, holidays are finally over and I got back to my project. I desoldered both of the MOSFETs and all pin combinations read around 1.3 ohms. Is it possible both of them shorted out, or did something else on the pcb cause this? I am going to go head and order new ones.