In the past days I dumped the PALs from an unusual two layers Crystal Castles PCB (with Atari EPROM strickers)
PALs were two PAL16L8 and three PAL10L8, all were unsecured.Then I converted them to GAL16V8 fusemap and Andrew Welburn successfully tested them on his board, thanks to him for the feedback.
Although issues were different in these two repairs (well, quick fix more than repair), the cause was the same.
Here’s the first board, a Super Spacefortress Macross :
Board had issue on some backgrounds which showed colored blocks :
A visual inspection revealed a lift pin on a QFP custom ASIC:
Reflowing the pin fixed the game:
Second PCB was a DoDonPachi :
with wrong music and sound FXs:
Also here the culprit was a lilfed pin (an address line, specifically) of the Yamaha YMZ280B-F (PCM/ADMPCM decoder)
Promptly fixed and sound 100% restored :
So, the bottom line is that you must always keep attention when you troubleshoot PCBs that use SMT devices, always check these for first…
Today we have some new PAL dumps.
Coolmod sent in dump from a Sonic Wings Limited PCB, device was an unsecured PALCE16V8 @IC1 (on the ROM board) labeled ‘SonyMo’.Thanks to him.
I dumped the PALs (two unsecured and unmarked PALCE16V8) from a DoDonPachi PCB.
All dumps have been successfully tested in a GAL16V8 or PALCE16V8
Got this original Juno First (by Konami) for a repair :
Board played fine but some sounds were missing, the most noticeable was the laser shot:
Here is a MAME record for a comparison:
All the sounds are generated by the AY-3-8910 chip.Probing it revealed that three I/O (pin 19-20-21) were stuck high, these should exchange data with same number of I/0 lines of the Intel 8039 MCU like shown in schematics:
The 8039 was dead, clock was missing on pin 2 and 3.I replaced the 8MHz quartz and the two 10pF capacitors with no change.This MCU has no internal ROM so it needs an external one :
Using a dummy ROM file in MAME reproduced exactly the issue, some sounds were missing like in my board.This lead me to think the MCU was bad so I removed it:
The 8039 is not widely used on arcade system but I was luck and found one on a Gyruss bootleg.Installed a socket and chip:
and all mssing sounds were back.End of job.
Today I dumped the PLDs from a Gun Force 2 PCB (Irem M92-B-G ROM board revision).Device were two secured PAL16L8 with no marking or label.There is another PAL but it’s set as registered so undumpable (but it seems not used since PCB works fine without it).Dumps have been successfully tested on GAL16V8 targeting device.