GadgetFreak
Active member
I bought this "untested" Choplifter off Ebay and of course it was faulty, funny thing that as all his other boards were tested!
It's actually a Tecfri Licensed version but is identical to the Sega.
Anyway after the standard delay it starts with the tests, does the full screen flicker bit then just as it starts with the descending blocks it comes up with "BAD IC 0002". It's an 8k ram which is normally soldered but this one has very recently had a socket put in!!!!!!!
Anyway tried a known good one but still errors, so it's not the ram. You know whats coming...... I fire up my "Slice" tester and start working through the chips associated with the video ram access. Within minutes I get the following from IC24 a 74ls155.
So I dig out my existing board and get the following:
So I cut out the '155, socket and replace, board is now perfect.
This is the kind of chip fault that I would have difficulty finding with a standard logic probe, the pins are still active but not quite correct.
The next step for this board and the reason I bought it, is to convert it to a System 2 Wonderboy when I find the time. Someone, I can't remember who, asked me to get a proper Wonderboy decrypted so now I have the board the only thing holding me back is time. First up is getting "Slice" out for some Beta testing then I'll get to work.
It's actually a Tecfri Licensed version but is identical to the Sega.
Anyway after the standard delay it starts with the tests, does the full screen flicker bit then just as it starts with the descending blocks it comes up with "BAD IC 0002". It's an 8k ram which is normally soldered but this one has very recently had a socket put in!!!!!!!
Anyway tried a known good one but still errors, so it's not the ram. You know whats coming...... I fire up my "Slice" tester and start working through the chips associated with the video ram access. Within minutes I get the following from IC24 a 74ls155.
So I dig out my existing board and get the following:
So I cut out the '155, socket and replace, board is now perfect.
This is the kind of chip fault that I would have difficulty finding with a standard logic probe, the pins are still active but not quite correct.
The next step for this board and the reason I bought it, is to convert it to a System 2 Wonderboy when I find the time. Someone, I can't remember who, asked me to get a proper Wonderboy decrypted so now I have the board the only thing holding me back is time. First up is getting "Slice" out for some Beta testing then I'll get to work.
. How much are you selling for ?? What type of reader would you need ?? Sorry for questions, Always looking for better ways to test things. I Am just using an IC identifier and MiniPro - Does a good job to be fair but cant have enough kit.