BYTE: Part 12 - ULA Replacement

Unfortunately ... didn’t fix the issue. All three of the red BYTEs I have show similar symptoms - the black Spectrum-like BYTE uses discrete logic and works fine. I had three apparently new-old-stock (NOS) КА1515ХМ1-216 (aka Т34ВГ1) ULA-type of modules. Used one in this replacement. I wonder if there is a way to do some sort of verification out-of-circuit ... ? I will have to continue troubleshooting - there can’t be much more that could be wrong ... ? Other videos about this ZX Spectrum clone from Moldova: