Pcenginemods' pc engine gt external gamepad connector issue

[pipi]

Hi everyone,

I am the proud owner of one of the controller board replacement that were sold on pc engine mods probably by turbokon (if I remember right).

All working amazing until today I finally tried it with an avenue pad, I immediately started street fighter 2 and when I go to the buttons screen and enable 6 buttons it flickers super fast and stops working properly.

Is there anything I can check?

Same pad and game work perfectly in normal core grafx.

[pipi]

Very interesting update!

If I connect a multi tap to the pc engine gt all works great, including the 6 avenue pad in 6 buttons mode...
Is this the way it should work, only using a multi tap?

[Keith Courage]

Not sure if it is supposed to work that way but I bet it has something to do with the built in controller board for the handheld being 2 button. Using the 6 button pad must cause issues but when running through a tap(disables the built in controller board altogether) the 6 button pad works fine.

[pipi]

Hi Keith!

TBH I am more than happy in using the multi tap but I am just curious about the inner working.
I hope that maybe some controller board builder will pop up and explain.

Thanks for your input

[MasterofBiscuits]

Very interesting update!

If I connect a multi tap to the pc engine gt all works great, including the 6 avenue pad in 6 buttons mode...
Is this the way it should work, only using a multi tap?

I don't know much about that replacement board, but I do know if you wire up a controller port to a GT this is the same behaviour (only works properly with a multitap). Someone has mentioned it needs diodes to work properly but I haven't looked into it myself.

tawy might be a good person to ask as he has also made a replacement board with a controller port.

[tawy]

hello
yes, the diode is there to stop the signal from the controller board to the 2nd controller. if a single controller is connected to the original controller board, the console does not understand if 2x 1st players are connected simultaneously and have the strange behavior you just mentioned. the multitap certainly has built-in diodes.
my version of the board is the same as turbokon, i just followed the trace design of the original board to make it look cool, and the signal has larger traces to make it stronger. It's "just" a game controller PCB, I followed the schematics of a real PCEngine controller and added 4 diodes on each signal because turbokon did that too
I tried with and without a controller and with a multitap, it works perfectly.

[Keith Courage]

So I just tested an Avenue Pad 6 with a recent external controller port mod I did and all 6 buttons work flawlessly with SFII. No tap needed.

I'm seriously wondering if that controller board in your Turbo Express has the Diodes in there. Otherwise, I can't really think of why it would need a tap to work correctly.

[pipi]

Sorry I have been a bit busy with work...
How can I add the does in case they are missing?
Where should they be?