SOLVED! - Turboexpress input board problems. UP and button II not working

[bovined]

Hello all, I hope there are some experts here who can help. I finally bought a Turboexpress after having missed out on it during my childhood and have an issue with what I HOPE is the input board and not the system board. The seller had already recapped the system for the audio and video but noted that the UP direction and button II only worked intermittently. Once I received it I see that neither input seems to work at all so I disassembled the unit to see what might be the problem. the ribbon seems fine but when I flipped over the input board I see this mess:

Any thoughts on what is going on in this board that could be preventing UP and button II from working properly?

Thanks for any help in advance!

[Keith Courage]

Either the pads for the buttons need cleaning or there are bad traces. Those boards are known for getting bad traces.

[thesteve]

you need to do continuity tests on all the traces in the effected area
also test the ribbon

[bovined]

Thanks for the help folks. I broke out a multimeter and tested all the traces on the input board all the way through the controller chip and the leads out the ribbon cable and out to the other end and assuming I am doing that part right (placed the leads at every two way point to check for signal) it appears I should have continuity all the way through from the button pads out through the ribbon. I tested the ribbon connector on the system board and reflowed one of the legs there that seemed intermittent but after putting everything back together I still have the exact same problem: system does not seem to register up arrow or button I (I incorrectly said button II earlier)

I dont know what to check for as far as inputs once they go into the system board. Any other thoughts on what I could check for?

[mickcris]

Have you checked these 3 areas I circled in red?



It looks like some of those traces may be bad, but hard to tell if its just reflection

[bovined]

Thanks for the lead...I did check the traces in the top and left circles areas and they appeared to be fine. I assume you are referring to the two black ones in the right hand circle? If so then yes they also seen to be fine.

I found this older thread that sounded like it might be the same issue: http://www.pcenginefx.com/forums/index.php?topic=6806.0

But when I checked the right side of the chip that appeared to have extra solder and attempted to clean it up I now have corrupted audio that buzzes through both the speakers and headphone jack in along with the non working inputs so not sure what happened there. It looks like there may be some solder stick in between two of the chip legs now so hopefully that didn't cause a short somewhere...does that area of the chip have audio functions???

[Duo_R]

I had a control board I fixed for a member a while back. Couple traces were corroded I actually had to make a new "button" to fix, I think I posted it but this was several years ago. I used a tiny micro switch since the board was so bad couldn't be repaired to work with a normal button. I believe it was Run and II were bad. Now if a directional button trace is bad, I would just rebuild a little circuit for direction. As long as the ICs are good this isn't difficult.

[thesteve]

The sound doesn't go to the chip
Let the screen time out, then push a non working input
If it wakes up the issue is between the controller chip and the 6280 on the main board

[bovined]

Thanks for the help and tips guys. I cleaned up and reflowed the ASIC #HUC6280 on the system board again under the RF shield and now everything works! No sound issues and inputs are all good.

Thanks again!

[thesteve]

the HuC6280 is a 6502 CPU with extended code, not an ASIC