DIY EmotivaTroubleshooting - Beware! Component Level!

[mosfetman]

I love Emotiva gear! We all know why: it's affordable, it sounds great, but most of all, it looks SEXY! so lets be honest about that.

Anyway, today we will be talking about a common point of failure with Emotiva Preamps and Processors- the power supply. Also, I will be focusing on the repair of a legacy UMC-1 that has the classic "Loading...." screen of death but this symptom is also found on similar Emotiva stuff. 

I will describe here in plain English what is going on. If anyone would like a flow chart or pics, just PM or email me and I will try to provide them. For now, let me ramble with some groundwork: 

• Power Supply Specs:  The Power Supply in many of the Emotiva preamps/processors have five outputs  ; +15V, +12V,-12V, +10V, and +5V. 
• Regulators used are:  7805, 7812, 7912. I can't figure out how they are regulating the 10V which is bussed throughout the device,15V is unregulated. More on this later.
• The Display logic/circuitry displays "Loading..." while waiting for the other processors to boot.
• The Main processor board and I/O board each have MCUs that boot individually. They each have JTAG/Serial ports and their own RAM.

Failure Scenario #1  Very Common:

• All labeled 10V test points will measure +/- 15V
• 7912 and 7812 will be visually blown
• PCB area surrounding the main diode/bridge will look baked
• PCB area surrounding the 7912 and 7812 will look baked
  
• Z1016A1 Buck converters on Main board will be damaged, visually clear.
• FB4 (SMT fuse by the Z1016A) will be open

Hope this helps. You can send me measurements and waveforms and I will try to help with your problem. 

I'm looking for a spare UMC-1 power supply or for a dead UMC-1 if you have one for sale or donation. 

Always better with MosFets!
JP