Star Wars AVG Board #3 board is dead

Smitty420

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Started working on board#3 and I get nothing. No signs of life during self test or otherwise.
Started by metering RAM buss and AVG socket. About to pull socket and noticed a scratch mark across the middle. Putting a meter to it show short between tei traces and 5v rail as well. Ran a pointed edge across the traces snd thought it was clear but still shorted. Started pulling chips on the circuit and testing. Finally cleaed the circuits and still grounded. 😡

Went back to the original trace scrape and had to run an sharp edge literally cutting into the board followed by the solder iron tip to get the short to clear. Usually I can clear them with the hakko snd the tip of my meter but not this one. It also took several passes.
 

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I just had a main board with this under 1F that was shorting data lines 3 and 4. What is wrong with people?
 

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That is super common on Atari boards, in my experience. The lack of solder mask on the parts side makes the tin coating on the traces flake off easily, and short to adjacent traces, when people stick screwdrivers, etc, under the ROMs to pop them out. However it can happen elsewhere on the traces, just from having something dragged across the PCB.

The easiest way to spot them is to hold the board up to a bright light, and look through the board (i.e., have the light behind the board). They really jump out when you have the light behind them, vs reflecting off the board. Whenever I have a bus-side issue, they're the first thing I visually check for.
 
Board still has vector issues will need more probing around the output section. Could be one side only from initial testing. Could be scaling as vector test n 5j doesn't have the right scope output. Might get pictures tomorrow.
 
That is super common on Atari boards, in my experience. The lack of solder mask on the parts side makes the tin coating on the traces flake off easily, and short to adjacent traces, when people stick screwdrivers, etc, under the ROMs to pop them out. However it can happen elsewhere on the traces, just from having something dragged across the PCB.

The easiest way to spot them is to hold the board up to a bright light, and look through the board (i.e., have the light behind the board). They really jump out when you have the light behind them, vs reflecting off the board. Whenever I have a bus-side issue, they're the first thing I visually check for.

Yea, this is usually the second thing I look for on boards, second board with trace issues on this repair rodeo. Board #5 only had a loose leg on a capacitor in the output section making the spacing off about an inch, like a space of blankness between the S and T in the word Star was he most noticeable. Easy repair, not really a repair but a quick fix.
 
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