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!
http://wiki.arcadeotaku.com/w/Twin_Cobra_Repair_Logs
A glitch chasing story
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You can add Repair Logs to the Wiki here.
You can add Repair Logs to the Wiki here.
- Asayuki
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A glitch chasing story
My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
- DaveyD
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Re: A glitch chasing story
I love reading repair logs like these. Always amazes me how people figure out how to reverse engineer these things. Nice work!
- Asayuki
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Re: A glitch chasing story
Thanks
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.spmbx wrote:Seems like with a little effort you could have recreated the entire board from scratch, or am i going too far now
My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
- Stompp
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Re: A glitch chasing story
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
- Asayuki
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Re: A glitch chasing story
Hmmm.... that looks strikingly familiar.Stompp wrote:I have the same kind of bootleg T.C. with another kind of issue though (https://youtu.be/N7HT2qfqMLU).
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
- Posts: 732
- Joined: July 10th, 2012, 10:58 am
- Location: Stockholm, Sweden
- eBay: uridium
- Initials: DAD
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Re: A glitch chasing story
Thx, appreciated I've got some other stuff that needs to be taken care of first though (as usual )Asayuki wrote:Hmmm.... that looks strikingly familiar.Stompp wrote:I have the same kind of bootleg T.C. with another kind of issue though (https://youtu.be/N7HT2qfqMLU).
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.