Double Dragon PCB Problem

2HitWonder

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Looking for a little help for a buddy of mine who just picked up his childhood favorite: Double Dragon.
The game won't boot, it gets stuck on a screen that reads:
Work Ram: OK
Rom 1: OK
Rom 2: OK
Rom 3: OK
Rom 4: OK
63701 Error

The screen color also alternates between black and black (see pics)

Looking for ideas about what this might be.
 

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Found this in an old thread:

"Symptom #2: During boot, occasionally hangs on 63701 check, or gives 63701 error

- swapped the 63701 IC into a known-good board, works fine
- probed pins of the 63701 with logic analyzer, /HALT signal is always low
- /HALT comes from inverter at IC71 pin 6
- input to this inverter at pin 5 is also low - chip is obviously bad
- replaced it, boots consistently with no errors now

Solution: Replace inverter at IC71 on main board."

(http://forums.arcade-museum.com/showthread.php?t=206022)

Maybe a good place to start? What is an inverter?
 
an inverter is a gate that flips the signal. If a HIGH signal comes IN. A low signal goes out. 7406 and 4049 are basic examples

stick your logic probe on the points he talks about.
 
Have met this three times so far, in each of the 3 cases the issue was the TMM2015/2016/2018 SRAM that is closest to the 63701. It is more likely to be the RAM than a logic fault, but as always it could be any number of issues. Chief suspect in cases where there is black shiny topped TMM RAM is the RAM itself. Other makes of RAM and Toshiba RAM that is dark grey rather than gloss black are more robust.
 
6116 ram will probably work as a 2016 and may be easier to find. Just make sure you get the package width correct, they come in 0.3" and 0.6" i think.
 
6116 ram will probably work as a 2016 and may be easier to find. Just make sure you get the package width correct, they come in 0.3" and 0.6" i think.

It will. You just need the correct width and speed - the same speed or faster. Don't go slower unless you know for sure the speed of the IC will work.
 
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