Veryveryfamous
Member
- Joined
- Feb 23, 2011
- Messages
- 7
Dear Group DIY, many thanks for all I've learned reading this board over the years! A particularly tricky project has come across my desk and I'd love to hear any insights you may have.
I'm working on a Lexicon 480L that has had a power supply problem and is now blowing fuses. This box came to me with problem on it's 15V rail. I isolated the problem to the unit's mother board and I found a shorted 7815 regulator. Unfortunately when I replaced that, it started blowing fuses…
I've gone through and replaced all the regulators in the linear power supply along with the filter caps, and all the tantalum caps on the board. Disconnected from the circuit, the power supply works fine but as soon as I connect it the fuses blow. Obviously something is drawing too much current but when I measure between power and ground I'm seeing a load in the range of 2.5K, not an outright short.
It's a huge PCB but I'm not seeing any visual damage or suspicious parts. Any ideas how to track down what's blowing the fuse (hopefully leaving the ~15 custom ICs on this board intact!) ?
Thank you!
I'm working on a Lexicon 480L that has had a power supply problem and is now blowing fuses. This box came to me with problem on it's 15V rail. I isolated the problem to the unit's mother board and I found a shorted 7815 regulator. Unfortunately when I replaced that, it started blowing fuses…
I've gone through and replaced all the regulators in the linear power supply along with the filter caps, and all the tantalum caps on the board. Disconnected from the circuit, the power supply works fine but as soon as I connect it the fuses blow. Obviously something is drawing too much current but when I measure between power and ground I'm seeing a load in the range of 2.5K, not an outright short.
It's a huge PCB but I'm not seeing any visual damage or suspicious parts. Any ideas how to track down what's blowing the fuse (hopefully leaving the ~15 custom ICs on this board intact!) ?
Thank you!