After checking the power rails it was obvious that the 5v regulator wasn’t working, so the first action was to replace it.
![](https://www.bitwrangler.uk/wp-content/uploads/2020/12/IMG_20200816_120302-scaled-1-768x1024.jpg)
With the regulator replaced I hopefully tried the power again. This time all the power rails looked good, but still no picture. After checking with my multi-meter and oscilloscope everything looked good. Clock signals fine, memory address and data lines ok, ULA video output ok….. I was at a bit of a loss.
While thinking the problem over I decided to apply the composite video mod in the hope that when it did work at least it would look better.
![Spectrum Composite Video mod](https://www.bitwrangler.uk/wp-content/uploads/2020/12/IMG_20200815_134402-scaled-1-1024x768.jpg)
With that completed, I plugged in once again to start diagnosing the problem, and surprise …. I had a picture. So the problem must be with the analog video out.
I wasn’t out of the woods yet, I had the typical memory fault colour bars on boot. Using my new diagnostics cartridge quickly identified the two upper DRAM chips that were to blame.
![Upper memory faults](https://www.bitwrangler.uk/wp-content/uploads/2020/12/IMG_20200829_134427-scaled-1-1024x768.jpg)
The upper DRAM was already socketed making replacing very easy.
![](https://www.bitwrangler.uk/wp-content/uploads/2020/12/IMG_20200815_134353-scaled-1-768x1024.jpg)
With the fix complete it was time to play some games 🙂
![Playing Attic Attack](https://www.bitwrangler.uk/wp-content/uploads/2020/12/IMG_20200819_164049-scaled-1-1024x768.jpg)
Still some cosmetic fixes, but that’s a later post.