Amp came in like yeah....big damage, blown rail caps, burnt PCB and so on.
I took this one just as I challenge if I can fix it...
I've fixed a lot of stuff, I know doesn't seem all that shiny and glossy, but should do the job.
There are burnt traces from the driver IR2010. I'm missing COM and VSS. As I do not have any schematics, i've tried to to follow the datasheet for the driver.
So COM goes to negative rail, but where does the VSS goes to ? Positive rail ?
I took this one just as I challenge if I can fix it...
I've fixed a lot of stuff, I know doesn't seem all that shiny and glossy, but should do the job.
There are burnt traces from the driver IR2010. I'm missing COM and VSS. As I do not have any schematics, i've tried to to follow the datasheet for the driver.
So COM goes to negative rail, but where does the VSS goes to ? Positive rail ?
Attachments
This amp uses a different drive circuit but the supply connections to the IC should be the same. It's on PDF page 42.
Thanks Perry !
So both connect to -rail/-vcc,, that seems odd. What's the point of making two different traces but connecting to the same thing ?!
I'm almost 100% sure COM goes to -Vcc as looking at the burnt trace....but Vss...wait doesn't the chip itself see the negative rail as its reference point/ground ?
So both connect to -rail/-vcc,, that seems odd. What's the point of making two different traces but connecting to the same thing ?!
I'm almost 100% sure COM goes to -Vcc as looking at the burnt trace....but Vss...wait doesn't the chip itself see the negative rail as its reference point/ground ?
They aren't always connected directly together. I've seen some where they were separated by the shunt resistors on the negative rail (one on the rail and one on the high-side of the shunt resistors.
I've connected COM and VSS across the shunt resistors. PS section is fine, pre-amp is fine, voltages are OK, but no class D switching.
It seems that 74hc02d is dead (square wave in, no output, but I don't have any left in stock so I have to order), couple of small smd capacitors (i don't have any idea what values they should be used some 100v 100nf ), some resistors are out of tolerance more than 20% and going this route i'm pretty sure I would also need new IR2010....
There are also two diodes which are bad and I can't read anything as a marking on them. For D101 - i've used 1N4148.
ZD101, ZD102 look like 5v zeners and are working fine. but the ZD103, it's bad and I don't have any idea what it is.
It seems that 74hc02d is dead (square wave in, no output, but I don't have any left in stock so I have to order), couple of small smd capacitors (i don't have any idea what values they should be used some 100v 100nf ), some resistors are out of tolerance more than 20% and going this route i'm pretty sure I would also need new IR2010....
There are also two diodes which are bad and I can't read anything as a marking on them. For D101 - i've used 1N4148.
ZD101, ZD102 look like 5v zeners and are working fine. but the ZD103, it's bad and I don't have any idea what it is.
Attachments
Exactly, it is. I will order new 78L05, but what about the zd1 zener diode ? It reads something like 7 ohms ?
It's defective, reads the same out of the circuit.
It's actually ZD4...there are some markings on it, but I cannot read them without a microscope...
It's actually ZD4...there are some markings on it, but I cannot read them without a microscope...
I have it as a 13v Zener MM3Z13. Digikey has several versions.
https://www.digikey.com/en/products/base-product/onsemi/488/MM3Z13/31314
https://www.digikey.com/en/products/base-product/onsemi/488/MM3Z13/31314
Fixed that. Amp stays stable at idle.
Once there is a signal applied to the RCA it draws as much current as it can. Output mosfets are getting extremely hot in a few seconds and there is some dc at the output.
I've change the gate resistors, the IR2010, the 7402, new mosfets IRFB4227, still doing the same...even if I only touch the rca input pin (not the shield) it draws excessive current.
I think both mosfets at the low and high side are turned on at the same time...
Once there is a signal applied to the RCA it draws as much current as it can. Output mosfets are getting extremely hot in a few seconds and there is some dc at the output.
I've change the gate resistors, the IR2010, the 7402, new mosfets IRFB4227, still doing the same...even if I only touch the rca input pin (not the shield) it draws excessive current.
I think both mosfets at the low and high side are turned on at the same time...