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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: wilykat on August 07, 2015, 05:42:14 PM

Title: Controller doesn't work right, no U, D, R, or L
Post by: wilykat on August 07, 2015, 05:42:14 PM

TG-16 controller I just dug out of the mess of untested controllers I sometimes pick up from Goodwill, Salvation Army, various sales, and even in rubbish bin.  It's acting odd.  When I press U, D, L, or R, nothing happens.

Using controller test ROM (via Everdrive), it confirmed nothing working on the control pad.  HOWEVER if I pressed Start, Select, I, or II button, it also triggers direction.  Examining the schematic, the common issue seems to be data toggle line to pin 1 of 74HC157 is not toggling and stuck in high. I checked the wire and PCB trace, there is continuity from the plug all the way to pin 1

Using a logic probe, I am getting pulse on pin 1 so the signal is getting through.

Does it mean the chip is partially bad?  The 4 buttons still work but directional does not work.  Or is there something else I need to check first?

Title: Re: Controller doesn't work right, no U, D, R, or L
Post by: thesteve on August 07, 2015, 08:25:34 PM

sounds like a bad chip