Got this pcb to be repaired from a friend.
The pcb was working perfect excepts that the screen was flickering at 1/2 of the vsync.
As usual I visually inspected the board to find loose legs on smd chips but the only one present was good.
I noticed that the pcb had 4x rams 4164 near the video custom chip which are known to be not very reliable.
I started to probe the rams until I found one which had all the signals very weaks.
After soldering a new one, the problem was fixed!
dj_yt has tested the above decrypted version of E-Swat and all is well.
Thanks to dj_yt for testing and reporting back.
In the past days we received some new PAL dumps. For now we mark them as untested since we yet have no feedback on them.Most of dumps came from ‘coolmod’.He sent in dumps from a Gaiapolis PCB (two boards PCB revision), this is the only which has been tested and working in a GAL16V8.Then, he submitted dumps from various boards :
These are untested for now (the ones from Hat Trick Hero ’93 are still in native PAL16L8 format) as well as the dumps we got from Smitdogg on Dumping Union from a laser disk game called Mahjong #4 Shabon-Dama.Thanks to the dumpers for their contribution.
Another pcb which was part of the cheap deal.
It was completely dead. Given that it is not an interesting game I was about to use it for spare parts when I asked my friend Caius if he ever repaired a Namco NA-1
He told me he once repaired one with a capacitor connected to the reset circuit of the 68000 which faulty and didn’t produce the reset signal.
I tested mine and to my surprise the reset was stuck low.
I changed the capacitor smd 22uF @C5 with one 1uF which I had available and the game booted.
Unfortunately the sound was completely missing, so I probed with my portable amplifier some smd capacitors which are know to be leaking very easily and I found one which interrupted the sound to the main ampli.
After changing it, the sound was very low with lot of background noise.
To end a long story short, I recapped many small smd caps with new ones and restored full volume.
This is a common problem with Namco NA-1 pcbs
I got this pcb togheter with other games all untested as part of a very cheap deal
When I fired it up, I noticed that it worked except sound.
This game has a rare Toshiba sound cpu T5182 which is an embedded z80 with ram and rom inside the same package.
One trick to know if the problem lies in the sound cpu is to coin the game. If it works, than the cpu, which also handles the coin inputs, is fine.
That was the case with my pcb, so given that I could hear noise from the speakers, I troubleshooted the pre amps with my portable amplifier.
There are two op amps, one is a 4558 directly connected to the Ym3016 DAC, and the other is connected to the 4558, which is an LM324.
The latter had all the outputs dead, so exchanging it with a good one restored the sounds.
