Hi all,
another level of my quest to defeat Brawshella has been completed.
This time it's a bootleg Twin Cobra board with some facepalm issue on an add-on card replacing some custom chips.
The repair itself definitely belongs in the hard class, but I cut as short as possible the otherwise interesting story of this troubleshooting effort. If you are curious about getting further details then let me know. I am however pretty sure the community can make good use of the reverse engineered data available in this article.
As usual, comments, suggestions and constructive criticism are welcome. Happy reading!
spmbx wrote:Seems like with a little effort you could have recreated the entire board from scratch, or am i going too far now
With the information I have gathered, it would be no problem at all to create a T.T-2 replacement; but that would require way more time and money than the ones a bootleg would be worth investing into. For an original with a broken T.T-2 I would have probably done it.
My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
Thank you for this. I have the same kind of bootleg T.C. with another kind of issue though (https://youtu.be/N7HT2qfqMLU). Haven't bothered about it thus far, but now you got me thinking
Stompp wrote:I have the same kind of bootleg T.C. with another kind of issue though (https://youtu.be/N7HT2qfqMLU).
Hmmm.... that looks strikingly familiar.
If you have a scope you might want to check HSYNC and VSYNC at the T.T-2 for amplitude and smoothness. By syncing to VSYNC and poking around the RAM address outputs you should clearly see the mess happening. The title logo completely belongs to the T.T-2 that sits close to the Z80, except the helicopter.
But your issue looks much more severe than mine. Maybe one of the ICs on the add-on card is gone?
Of course it can still be oxidised contacts in those pesky two-rows connectors or an issue with the monitor...
Let me know if you need further help.
My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
Stompp wrote:I have the same kind of bootleg T.C. with another kind of issue though (https://youtu.be/N7HT2qfqMLU).
Hmmm.... that looks strikingly familiar.
If you have a scope you might want to check HSYNC and VSYNC at the T.T-2 for amplitude and smoothness. By syncing to VSYNC and poking around the RAM address outputs you should clearly see the mess happening. The title logo completely belongs to the T.T-2 that sits close to the Z80, except the helicopter.
But your issue looks much more severe than mine. Maybe one of the ICs on the add-on card is gone?
Of course it can still be oxidised contacts in those pesky two-rows connectors or an issue with the monitor...
Let me know if you need further help.
Thx, appreciated I've got some other stuff that needs to be taken care of first though (as usual )
but I cut as short as possible the otherwise interesting story of this troubleshooting effort. If you are curious about getting further details then let me know. I am however pretty sure the community can make good use of the reverse engineered data available in this article.
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