Hyper Olmpic (Track and Field) PCB repair

 Arcade Info  Comments Off on Hyper Olmpic (Track and Field) PCB repair
Dec 082020

I’ve had this Hyper Olympic board sat in my repair pile for more than 5 years.  I kept coming back to it, but never really made any progress, mainly because the schematics are poor.

On initial power up I got jumbled sprites for the runners and lines through the background, text and logos

I took a video back in 2015 here:

It was originally labelled a Hyper Olympic board, so I thought this might be why the logo was messed up so I changed it from a Track and Field to a Hyper Olympic, but that wasn’t the case and the issue persisted.

I also used ShoeStrings test rom at the time to see if it could identify any issues and unfortunately this did not help. Here is a video:

I used my logic probe back in 2015 and looked through the board and noticed some stuck pins on two of the eproms between 11C-15C, and traced this back to a faulty LS04 @ B6.  I swapped this out and the runners were back.  The only issues that persisted was the lines and faulty logo. I took a video here

Fast forward to the end of November 2020, and I picked this up again.  The background and text were missing details and the logo had wrong colours and there was jailbars as in 2016.  I was fairly confident the problem was around the roms D10-D12 @ H14-16 and the 273 @ 14G was the next part in the chain.  I took at look at that but found no issues.

If I removed D10-12 and the two rams @ 11-12H I could still see lines on the screen, so I came to the conclusion that they were not affecting the lines.

I had a look on the scope and again didn’t see anything obvious.  I spoke with a fellow collector and he suggested that I started to short pins to see if I could narrow the area a bit.  This is where I got my break through.  I started to ground the data pins on the D10-D12 roms and found that if I grounded the D0 pin on the roms I could replicate the issue.  This narrowed the problem potentially down to 2 chips:

My money was on the LS273 because it was a Fujitsu, so it was the first one I changed. Sadly the issue persisted. So I then decided to also change the LS157 @ 15G as I was confident the problem was definately here. I am glad I did because I powered on the board and was glad to see the ongoing 5+ year long board was now fixed!