After about 30 years, the original Sord m5 power supply started delivering unstable power levels. It stabilized at the nominal voltages a few minutes after switching on. So everything pointed to dried up electrolytic capacitors. The function of the computer was mainly manifested in the instability of VDP and video memory, where character sprites were greatly altered, image synchronization was unstable and iridescent colors ran across the image. You can see the said behavior in the video below…
By measuring the individual voltages, it turned out that the +12V voltage was the main culprit of the unstable image. Immediately after switching on, instead of the 12V, I measure a little over 10V. The image normalized to somewhere around 11.8V
Right after psu disassembly I didn’t find any sign of “bloated” caps
The repair itself is trivial and can be done by anyone who has a soldering iron at home. There are a lot of electrolytes in the psu,but I only replaced C1, C2, C5 and C8. Their values are as follows:
Notice how the printed circuit board is blackened under the diodes. Either as guys we played games A LOT or we overloaded the supply with various peripherals. It’s true that 200mA is not much.
After replacing the capacitors, the psu works as it should again. If you want your power supply to last another 30 years, I recommend you use higher quality capacitors with low ESR