Sunday, July 20, 2014

Minima - Damage Report

After returning home from Salmoncon 2014, where I had my Minima Transceiver Modules on display and for demonstration, I decided to again add some more functionality to my Minima Alternate Tuning Method software.

My Minima Transceiver Modules
This photo was taken at Salmoncon 2014,
Thanks to Linda -
AB7YL
But at home, when I turned the Minima ON, it ran for a short time and then went blank. A second attempt at Turn ON, was equally as bad, the LCD presented large black-blocks for the top row of characters.

My Minima CPU Board has Died!

The Problem

The voltage on the 5.0V Rail was measured at 7.8 Volts. The regulator was fried, which I am sure that voltage cooked the ATMEGA328P-MU Microprocessor as well. I knew the regulator was under rated for the increased load that I had put on it, but it had worked so far, even though it would get very warm.

The Attempted Repair

For repairs, I first replaced the 5 Volt Regulator.

Now the 5 volts Rail is correct, but the microprocessor is still toast!

My attempt to replace the microprocessor was NOT so successful, some traces were damaged while removing the micro. The micro had been solder through the back side of the PCB as a heat sink. De-soldering the heat sink heated the board and small traces TOO much, damage was almost inevitable. In hindsight, it would have been better to Hot Air reflow the part off. But I do not have Hot Air tools.

Dead Microprocessor

This of course is one of the pitfalls of using very small quad-flat-pack version of the microprocessor, if it were the large DIP, replacement would be a quick chip replacement. But, I like to use the smallest chips that I can find.

My software modification testing will have to wait until I replace the board, but I am NOT looking forward to re-building this Homebrew board with its 85 via's.

The Solution

I decided to pay the bucks, and have OSHPark.com manufacture a set of boards for me. The boards will be in hand in about a week. I will continue working on the Minima Software additions, but software testing will have to wait.

Maybe, this may provide time for me to finish my Homebrew Audio boards for the Minima.

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4 comments:

Eldon R. Brown SR said...

Comments Welcome !

Jeff Whitlatch said...

I have a hot air rework station which you are welcome to borrow anytime.

73's de Jeff - ko7m

pedro said...

Check the Si570 if is not damage too

Jeff Whitlatch said...

I have a theory of the source of the damage. In the photograph, I notice that your PCBs are laid out on a plastic picnic table cover. I wonder if a bit of ESD took it out...