Post by serafis on Jul 13, 2023 23:26:14 GMT -5
Update: DC and hiss on output was caused by fake TLC071ID op-amp from Aliexpress that had 18mV offset in a unity gain configuration - should be < 70uV. Fixed by installing a genuine one from element14.
I've just got hold of a lovely Integra DRX-7 AVR (9-channel) for almost nothing, as it's stuck in protect mode with AMP OVERHEATING displayed. I found the service manual on HiFiEngine (need to register and sign in to get it).
Having disassembled it, I find that one of the nine class-D amplifiers has blown its MOSFET driver (IRS20957STRPBF) and both MOSFETs (IRF6775MPBF), presumably caused by a speaker short or similar. I haven't found any issues with the surrounding components, including the temperature detection, so I'm hoping that replacing these will bring it back to like again. I've successfully removed the damaged parts and am waiting for replacements to arrive.
The MOSFETS use Infineon's tiny DirectFET ISOMETRIC package and I'm unsure how best to solder these with just an iron and a hot-air station. These MOSFETs look like the image below. The datasheet can be found ->here<-, and the Application Notes ->here<-
The Application Notes have detailed instructions on how to install them, including pre-heating the substrate to 100c and then reflowing using hot air at 260c, which i think I can probably manage with the hot air station. My question is how best to check that they are properly mounted before reassembly and powering up. Unfortunately, I don't have the ability to X-Ray them as the Notes recommend.
Has anyone here got experience of mounting this type of package, or any suggestions as to how best to do this, and to check that they have (re)flowed successfully?
TIA, Jon.
I've just got hold of a lovely Integra DRX-7 AVR (9-channel) for almost nothing, as it's stuck in protect mode with AMP OVERHEATING displayed. I found the service manual on HiFiEngine (need to register and sign in to get it).
Having disassembled it, I find that one of the nine class-D amplifiers has blown its MOSFET driver (IRS20957STRPBF) and both MOSFETs (IRF6775MPBF), presumably caused by a speaker short or similar. I haven't found any issues with the surrounding components, including the temperature detection, so I'm hoping that replacing these will bring it back to like again. I've successfully removed the damaged parts and am waiting for replacements to arrive.
The MOSFETS use Infineon's tiny DirectFET ISOMETRIC package and I'm unsure how best to solder these with just an iron and a hot-air station. These MOSFETs look like the image below. The datasheet can be found ->here<-, and the Application Notes ->here<-
The Application Notes have detailed instructions on how to install them, including pre-heating the substrate to 100c and then reflowing using hot air at 260c, which i think I can probably manage with the hot air station. My question is how best to check that they are properly mounted before reassembly and powering up. Unfortunately, I don't have the ability to X-Ray them as the Notes recommend.
Has anyone here got experience of mounting this type of package, or any suggestions as to how best to do this, and to check that they have (re)flowed successfully?
TIA, Jon.
