Ultimate 1MB in 1200XL?

[Brian W.]

5 hours ago, Brian W. said:

I've been reviewing and checking over things while waiting on parts. ....

Update. I've been trying for hours to correct some issues with the sparta dos hang on both U1MBs. I moved a setup to my 800XL for some base line testing. I get the exact same results, the in ablity to find the U1MB with the firmware update, and black screens on a regular basis. I've loaded Altira up, but nothing else works. It progressively failed on each one. The Side2 cart however has loaded sparta fine each time. So all of my cross comparisons lead to the noisey RST line causing what looked like a normal clean installation to fail and corrupt it enough that I could no longer do it again.  Taking lead from Flashcat's guide, I'll be getting a MiniPro TL866CS and reflashing the roms. Meanwhile, I'll be waiting for the 1nf cap and the IC replacements to show up. I'll try it all again from the start with these patches persay and see where I end up.

[Brian W.]

Good news, after replacing caps, the 2 multiplexer ICs that are recommended to be swapped out for new & re-flashing the SST 32pin eprom. Then scouring over the board with a scope. It looks like I've remedied the issue. My system is working perfectly, and in harmony with the Side2 Cart. I love this thing ! It gave me so much grief to start. But the all of the hard work paid off. Many thanks to all of those that have added viable suggestions to this post. 

[Spudster]

On 3/18/2016 at 5:04 PM, flashjazzcat said:

The LONG saga of this particular 1200XL finally reached a conclusion, thanks to Matthias Reichl (Hias), who deduced from video footage of the corrupted BIOS setup menu that the IO RAM could be inopportunely disabled by a noisy reset line. The suggested fix (unlike anything else previously attempted) which appears to have cured all issues is a 100pF capacitor between Reset and GND on the Ultimate 1MB. I chose a GND pin on the PLCC flash ROM:

 

 

Needless to say, I have a lot more testing to do before I'm 100 per cent certain it's completely fixed, but initial results are very encouraging indeed, with no trace of menu corruption or other unexpected behaviours.

So I performed this fix on one of my U1MBs last night and now she boots to a green screen. Removing the cap didn’t fix. Swapping the firmware chip with a known good didn’t fix. I used this capacitor: https://www.mouser.com/ProductDetail/Murata/DE2B3SA101KN3AT02F?qs=sGAEpiMZZMv0NwlthflBi8ddnD0X2GHw0%2FILxWpTTd4%3D

 

Is my U1MB officially toast? Did I use the wrong cap? Can it be fixed?

 

I’m extremely hesitant to try this again before I can rule out the PEBK factor. Any help would be greatly appreciated.

 

~ Z

[Spudster]

On 11/28/2021 at 7:48 AM, Spudster said:

So I performed this fix on one of my U1MBs last night and now she boots to a green screen. Removing the cap didn’t fix. Swapping the firmware chip with a known good didn’t fix. I used this capacitor: https://www.mouser.com/ProductDetail/Murata/DE2B3SA101KN3AT02F?qs=sGAEpiMZZMv0NwlthflBi8ddnD0X2GHw0%2FILxWpTTd4%3D

 

Is my U1MB officially toast? Did I use the wrong cap? Can it be fixed?

 

I’m extremely hesitant to try this again before I can rule out the PEBK factor. Any help would be greatly appreciated.

 

~ Z

One important thing to note: I swapped in a known good U1MB (same 1200XL config, same ribbon cables) and all is well.

[_The Doctor__]

double check your components and work, make sure it's exactly correct and clean... if it's still dead- you might have scrambled it's brains- A reprogram of the xilynx chip and the flash chips may set it right. I'd do that in that order as well.

[Spudster]

So I configured and upgraded a Raspberry PI 3b+, built a cable, tested, wired it to my 1200XL (Xilinx chip would ID without the connection, but would fail flash without), then attempted to program, and this is the result:

After the first flash, I power cycled the 1200XL and still got the greenish screen. The second attempt was after another power cycle of the 1200XL. Same result.

 

I checked the cable config twice, and will check it a third time, but for now I'm at the burnout stage and need to take a break.

 

Here's a photo of the back of the board. Black dots show where I wired the cap:

 

Any additional suggestions would be welcome.

 

~ Z

 

P.S. At least I got my 3D printer properly calibrated tonight, so calling the day a win.

Edited December 8, 2021 by Spudster
Attached photo of PCB.

[_The Doctor__]

does it say the device is blank every time you program it? I only use the official programming package, so I am not sure if that info is just letting you know it cleared the chip and made it blank or if it's always blank...

 

That being said, if you program the Xilinx and the Flash chip as well, and the flash chip works in your known goo u1m... that would leave you with a dead xilinx chip or possibly ram if that is the case...

 

for completeness, can we see the flip side?

Edited December 8, 2021 by _The Doctor__