Bubble Symphony - Taito F3 Game PCB Repair:
I recently treated myself to one of my most sought after Taito F3 titles when I saw one cheaply listed on ebay.
I was originally concerned the game was a bootleg conversion as the seller had taken a photograph of the bottom of the cart which had a serial number of: M20J0122A which would be Puzzle Bobble 3.
So I contacted the seller who sent back a photograph with the correct M20J0104A serial for Bubble Symphony and even opened up the F3 cartridge on request to confirm it was legitimate.
With that I purchased the game and a couple of days later I had it in my hands:
However, due to my hectic work schedule I wasn’t able to test it until today and I was not very pleased to find the game has graphical glitches in the background tiles:
I felt a little deceived by the seller after having a fairly good conversation with him and this issue was never mentioned. Even the listing photographs of the game running appears to be cherry picked for times when these glitches were either very hard to spot or not visible.
But since the price I paid was extremely fair and cheap. I decided I would look into seeing if a repair was viable because well I am a open cart surgeon right?
Let’s look inside!
Nothing looks out of order. No cracked solder joints and no obvious signs of anything bad.
Since the graphical issues were only on the background layers I could immediately narrow my focus down to the three Mask ROM that hold that data:
Using my TTL Logic Probe I tested each of these Mask ROM pins for correct activity using a schematic for the equivalent M27C160 EPROM:
However, everything appeared to be functioning normally.
I knew these were likely the only possible issue, so I then programmed three M27C160 EPROM with the data from the bublbob2.zip that you can find in a MAME ROM set appropriate for these three Mask ROM (d90-08, d90-07 & d90-06).
I then started to carefully piggyback each of these Mask ROM one at a time while the game was powered on to see which Mask ROM would either glitch the affected regions (due to not being able to make proper contact on all pins during the piggy back) or correct the problem.
I quickly found that IC47 (d90-08) was the problematic Mask ROM and so I removed it:
I soldered in a socket and replaced the Mask ROM with the appropriately programmed M27C160 EPROM:
Voila!
The game is now fixed:
Does worry me that some Mask ROM are now starting to die such as this 27 year old one:
