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Batsugun Special Ver. repair log

May 122016

Received this Batsugun Special Ver. PCB for a repair:

Batsugun_Special_ver_Japan_PCB

Game played fine but colors were all dull and washed-out, take a look at this comparison with a MAME snapshot on the left:

colors_comparison

or this video:

This was a clear sign of some troubles in colors palette circuitry.After studying the hardware, I was able to locate this section by shortcircuting some address/data lines of two CXK5816 SRAMs @U39 and U40 and at the same time observing color changes on screen:

palette_circutry

Besides the two mentioned SRAMs, you can see some 74LS245 and two 74HC273 involved in data bus (the first ones in exchanging data from/to the two RAMs, the latter in latching).When I went to probe the two 74HC273 I found that input pin 13 of the one @U43 was stuck low and its corresponding output pin 12 showed only weak signals:

74HC274@U43_probing

So confident I went to remove it:

74HC274@U43_removed

When I tested it out-of-circuit it failed:

74HC273@U43_failed

Once fitted a good IC and powered up again the board, the game played great with no further issues.

fixed

End of job.

New archive for GAL replacements of bipolar PROMs

General 5 Responses »

May 072016

There are not only PALs on our beloved PCBs but also bipolar PROMs!

A bipolar ROM or briefly BPROM (“BIPOLAR” stands for the transistor technology used in the manufacturing process) is a OTP memory device, which can be programmed just once and hence the data programmed can never be erased.They were used for various tasks: address decoding, state machines, and video colour palettes, for example.Like every electronic part they can fail and nowadays obtaining a blank device is really hard and expensive.And even if you find it, your EPROM programmer probably doesn’t support BPROMs as they are obsolete parts.

Someone replace them with EPROMs mounted in a custom adapter but we chose GAL devices as replacement since most of times there is no need of adaptation (if you program them in the right way, obviously).Besides, GAL devices are really common and inexpensive.Last but not the least, they can have fast access times like BPROMs require.So,today we open a new archive for GAL replacements of bipolar PROMs, you can find it under the menu ‘PLD Archive’ on main page.I hope you will enjoy it and contribute to its growth.

Sega System 1 PAL update

PAL Updates Comments Off

May 072016

Today we have some new PAL dumps from Sega System 1 hardware.

Thanks to the work of ‘Tirino73’ and ‘f205v’ :

https://www.citylan.it/wiki/index.php/Wonder_Boy_(set_3_bootleg_2)

we have dump of the unsecured PAL16R4 @IC 67, I converted it to GAL16V8 and successfully tested on my bootleg boards.Silvio Grazini confirmed that it works also on original hardware.So now set is complete along with the dump of the other PAL16R4 @IC41 already in our database.

Besides, they dumped also the devices (a PAL16L8 and a PAL16R4) on the piggyback board, I converted them to GAL16V8 and successfully tested on my boards.

Thanks again to them all.

1941 : Counter Attack repair log #1

General, PCB Repair Logs 3 Responses »

Apr 252016

I had on the bench this mint 1941 : Counter Attack CPS1 boardset:

1941_Counter_Attack_PCB

Board played fine except for a minor sprite issue on some objects on backgrounds which manifested only on first level:

sprite_issue

The game use the ‘CPS-B-05’ ASIC on C-BOARD which acts as a GPU generating all the graphics:

CPS-B-05_C-BOARD

so I swapped a good known one from a Street Fighter II : The World Warrior boardset:

CPS-B-05_C-BOARD_SFII

All the sprites were restored so I had confirm the ‘CPS-B-05’ ASIC was bad (probably an address line was ‘spitting out’ wrong address).I could swap the entire C-BOARD but appearances count too so I decided to transplant only the IC on the original C-BOARD.

CPS-B-05_SF2_removed

I used an hot-air rework station covering the plastic connectors with tin foil as protection against heat:

CPS-B-05_reworking

To solder the chip I used the ‘drag soldering’ technique:

I succesfully tested the reworked C-BOARD and declared board as 100% working :

Hammerin’ Harry (Irem M81) PAL dump added

PAL Updates Comments Off

Apr 252016

Today ‘frsj8112′ from Arcade Otaku forums sent in dump of the specific PAL @7D from an Hammerin’ Harry PCB (Irem M81 hardware).Dump has been successfully tested by him on a GAL16V8 targeting device.Thank to ‘frsj8112’ for his contribution.

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