Quick repair: Pravetz 8D

Recently we found another Pravetz 8D on auction for a good price and in good condition. No matter that we have a few units in our collection, we decided to save this one as well. You can never have too many Pravetz computers. 🙂

On first sight the unit was in mint condition, even the waranty seal was still present. When we turned on the computer greeted us with a junk pattern on the screen indicating that there was something not right with it.

Time to take apart the computer and as mentioned, it looks like it was never opened before. The waranty seals were still present.

Removing the top lid reveals the prety clean inside. There was no visible damage on the motherboard nor any signs of corosion.

Firts step was to clean the sockets and chip leads with some IPA alchohol. The first problem we found was a bent lead on one of the 8164 RAM chips, which is strange because the unit looked like it was never opened before. Who knows what had been done before….

We proceded to testing the RAM with our tester and one of the chips turned out to be bad, but it wasn`t the one with the bent lead. Still this was not the cause of the issue, because the computer did not boot up corectly with the new RAM chip.

Time for some chip swapping between our donor machine. First chip we swaped was the EPROM and bingo it worked. 🙂 Reading the ROM with our EPROM reader proved that it was bad, so we burned a new 27128 EPROM

The final step was to dissasemble the computer copletely and clean it up. This included carefully removing the bottom sticker, which is in prestine condition and its also the perfect candidate to be scaned for reproduction purposes.

After cleaning everything was put back together.