Hi,
I have a OEM car amp that keeps blowing fuses. This amp in perticular has 2 x 25 amps fuses. (in fuse box, not in PCB circuitry )
Both fuses blows directly when new fuses are inserted and power goes on.
I know that it might be hard to tell what the exact cause would be.
PCB is surface glued but not too hard to remove.
So im satisfied with your "best guess" at this moment.
My guess is that it would be some component close to the power input. this since the issue affects both fuses.
Below is the PCB front / back.
Thank you !
I have a OEM car amp that keeps blowing fuses. This amp in perticular has 2 x 25 amps fuses. (in fuse box, not in PCB circuitry )
Both fuses blows directly when new fuses are inserted and power goes on.
I know that it might be hard to tell what the exact cause would be.
PCB is surface glued but not too hard to remove.
So im satisfied with your "best guess" at this moment.
My guess is that it would be some component close to the power input. this since the issue affects both fuses.
Below is the PCB front / back.
Thank you !
The two ICs flanking the 4 inductors in the center of the board are the most likely. If you wipe the heatsink compound off of them, you may find a part number.
The attached is may be similar to what they are, just a sample.
Do you have any experience with SMD or any repairs on circuit boards?
The attached is may be similar to what they are, just a sample.
Do you have any experience with SMD or any repairs on circuit boards?
Thank you for input 🙂
If I need to replace those then I need a heat blower and shielding for surrounding components.
... If this is what you mean by experience. (correct me if Im wrong.)
below is a better image of the component that you are pointing out.
Does both IC's blow at the same time ?
Is there a component behind them that kills both of them ?
If I need to replace those then I need a heat blower and shielding for surrounding components.
... If this is what you mean by experience. (correct me if Im wrong.)
below is a better image of the component that you are pointing out.
Does both IC's blow at the same time ?
Is there a component behind them that kills both of them ?
I don't like hot-air for repair work. A soldering iron, additional flux, desoldering braid and possibly ChipQuik or its equivalent.
By 'experience' I'm asking if this is your first repair or if you've repaired other pieces of electronics.
Do you have a variable power supply that you could connect to the amp and slowly ramp up the voltage?
If you measure across the 12v supply input terminals, what resistance do you read?
Had the vehicle been jumped/boosted due to a dead/flat battery when the amp failed?
By 'experience' I'm asking if this is your first repair or if you've repaired other pieces of electronics.
Do you have a variable power supply that you could connect to the amp and slowly ramp up the voltage?
If you measure across the 12v supply input terminals, what resistance do you read?
Had the vehicle been jumped/boosted due to a dead/flat battery when the amp failed?
Hi,
You are right. I'll use braid, iron and flux for this.
I have done some minor works on electronics before. Mostly capacitors. Only a few times with surface mounted.
I have a 12v PS that can deliver 2 amps. Sufficient ?
I meassured <1 ohm on pins shown in below image (.... to ground ofc). I guess that is a short ?
You are right. I'll use braid, iron and flux for this.
I have done some minor works on electronics before. Mostly capacitors. Only a few times with surface mounted.
I have a 12v PS that can deliver 2 amps. Sufficient ?
I meassured <1 ohm on pins shown in below image (.... to ground ofc). I guess that is a short ?
It would be better if you could vary the voltage but 2 amps could be safe. What I wanted you to do is apply voltage to see if either of those ICs started to heat up to help find the blown one.
Do both ICs read the same?
If the vehicle was jumped at the time the amp failed, RP diodes could be shorted.
If you lift those VCC12 terminals and they still read 0 ohms to ground, the IC is likely defective.
Did you find the right datasheet for the IC?
Do both ICs read the same?
If the vehicle was jumped at the time the amp failed, RP diodes could be shorted.
If you lift those VCC12 terminals and they still read 0 ohms to ground, the IC is likely defective.
Did you find the right datasheet for the IC?
I can vary voltage and amp, 0-30v, 0-2 amp.
Should I apply voltage on the VCC12 pin ?
both reads the same.
Car didnt behave strange. Either it died upon start or while driving. Its for a friend and they cant recall which. But bottom line is that there wasnt anything unusual with the car in general... beside the amp ofc.
I found the datasheet.
Snippet above is from the link below.
https://www.st.com/resource/en/data_brief/tda7802.pdf
I'll try to lift the VCC12 leg and read it,
Is it strange if both IC's blew at the same time ?
Failing component behind them maybe ?
Should I apply voltage on the VCC12 pin ?
both reads the same.
Car didnt behave strange. Either it died upon start or while driving. Its for a friend and they cant recall which. But bottom line is that there wasnt anything unusual with the car in general... beside the amp ofc.
I found the datasheet.
Snippet above is from the link below.
https://www.st.com/resource/en/data_brief/tda7802.pdf
I'll try to lift the VCC12 leg and read it,
Is it strange if both IC's blew at the same time ?
Failing component behind them maybe ?
Is it an idea to remove the components then mount it back into the car and see if...
1. No fuses blow
2. Meassure VCC12 and VCC34 pads
?
1. No fuses blow
2. Meassure VCC12 and VCC34 pads
?
UPDATE
Probably this diod that caused the issue (SM6A27T). Disconnected the smaller leg and the short is gone through the whole board.
Case closed I guess.
Probably this diod that caused the issue (SM6A27T). Disconnected the smaller leg and the short is gone through the whole board.
Case closed I guess.
If this is across B+ and ground, it was (could have been) acting like a reverse protection diode with the added benefit of clamping excessive voltage spikes.