FPGA replacment for the ZX8301 ULA and more

[stephen_usher]

Oh, turned pin sockets are not great for old chips. Dual wipe sockets have a far larger (many times) contact area and active pressure and are far less likely to give connection issues.

[lliont]

Hi
This is the latest version of the upgrade board and closer to a final (final lol)
Now it has 2 extra sound channels.
I'll try for a final with an even faster cpu, I hope it will work or else this is it with just a few error corrections.

[Derek_Stewart]

Hi Leon,

I must the SMD soldering is very good, it must be hard to do the larger chips.

[lliont]

Hi
It's not easy but after some practice it's easier, the most important thing is to initially align the pins correctly then it's easier but with care not to leave any pins shorted. If a pin is not soldered well you can try again but if there is a short-circuit this can be fatal for the ic and fpga's are expensive. The use of good flux soldering paste is important.

[Peter]

Hi Leon,

I have now received my ULA replacements, nicely soldered and packaged.
I like the more compact for factor. Thank you very much for all the work.

The video output is good, but unfortunately both units generate Minerva error messages:

The fault is the same for both units, so it does not look like a soldering mistake.
I have checked the TQFP soldering under a magnifying glass, and it is perfect (great job!)
The fault also comes up if I add an external RAM extension.
I have re-seated the original ULA two times and the fault disappeared each time.
Any idea what's going wrong or what I could test without re-programming the CPLD?

[tofro]

This definitly sounds like a faulty socket?

[Derek_Stewart]

Hi,

I also received a nes ULA replacement board, great quality, can not believe this was hand soldered.

I have ULA board installed in an Issue 5 QL, with Minvera v1.97, QIMSI, QL-SD, Tetroid TDI, with CF Inteface disabled. Connected to a RGB monitor.

Standard QL display looks very good, all Trump Card 896K is recognised, works correctly with QIMSI, and QL-SD configurations, with the updated QL-SD firmware.

Looks a very nice systen now.

[Peter]

This definitly sounds like a faulty socket?

Why? It works with the original ULA and the contact pressure should be higher with the thicker gold contacts now.
Zero effect of cleaning the contacts and re-seating.
I have two units and on both I can reproduce exactly the same message.

[Peter]

I also received a nes ULA replacemenf board, great quality, can not believe this was hand soldered.

Maybe not the same board? I have the latest minimal one, original ULA behaviour, no accelleration.

[Derek_Stewart]

Hi,

Looks the same board as the board that was delivered yesterday: