Re: Brett's STE - Repair thread
Posted: 26 Jan 2022 23:24
No diag cart yet, but I think it may be close by :)
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No diag cart yet, but I think it may be close by :)
I'd call that a minor victory. Well done matey, I salute you! There's life in the old girl yet.rubber_jonnie wrote: 26 Jan 2022 23:21 I'm feeling like a minor celebration. I traced A1 and found that it should be connected to pin 2 of the DMA. Only it wasn't, so I hooked it up and I now get this:
IMG_20220126_230722.jpg
Which I am going to take as progress since it looks like something is getting to video RAM, something I'd not seen before.
Clearly some work left to be done, but the little red led on my diag cart which shows ROM access is now flickering, a good indicator that ROM access is at least being tried. It was completely dead up until now.
Clearly something is going on and it is trying, so more checking to be done, I'll need to look at A2 next.
I also added some test points near the GST combel and I can see that A1 & A2 are connected all the way from there to the Blitter, the CPU and finally the ROM and A1 to the DMA. I am also seeing address line pulses all the way through now too.
More to do though, @exxos another one for your crash screen archive :)
Would be interesting (and possibly educational) to know where exactly the track broke. Have you narrowed that down yet?rubber_jonnie wrote: 26 Jan 2022 23:21 I'm feeling like a minor celebration. I traced A1 and found that it should be connected to pin 2 of the DMA. Only it wasn't, so I hooked it up and I now get this:
Not sure yet tbh, this was a late last night thing so all I did was compare with my working machine and wire it up to see what happened.derkom wrote: 27 Jan 2022 05:57Would be interesting (and possibly educational) to know where exactly the track broke. Have you narrowed that down yet?rubber_jonnie wrote: 26 Jan 2022 23:21 I'm feeling like a minor celebration. I traced A1 and found that it should be connected to pin 2 of the DMA. Only it wasn't, so I hooked it up and I now get this:
Still a way to go I suspect, but I'm definitely more hopeful now.BrettRogersUK wrote: 27 Jan 2022 00:40
I'd call that a minor victory. Well done matey, I salute you! There's life in the old girl yet.
Yippee!!!
Regards,
Brett
Just thinking it's another skill to add to your existing set!rubber_jonnie wrote: 26 Jan 2022 23:13Not you too!!JezC wrote: 26 Jan 2022 17:56 @rubber_jonnie Go on - you know you want to!
:poke: :hide: :fire: :fire: :fire:
Thank you :)Icky wrote: 27 Jan 2022 08:29 Good progress @rubber_jonnie, also a good read of the diagnosis and fixes under the capable hands of Dr RJ :)
Very true :)JezC wrote: 27 Jan 2022 08:55Just thinking it's another skill to add to your existing set!
Also, can be very useful to help work around faults or shortages. ;)