Some days ago I received this faulty Punk Shot PCB (manufactured by Konami in 1990)
Game had small glitches over the sprites and played mute:
MASK ROMs check reported two bad devices:
Usually jailbars mean some problem in data bus so I went to look at relevant circuit.As in many Konami PCBs the sprites generation circuit is condended in two ASICs : the ‘051960’ which generates the address lines for the MASK ROMs and the ‘051937’ which reads data.Indeed I found a missing connection beetween pin 84 of the ‘051937’ and pin 28 of the 8Mbit MASK ROM @K7
This was caused by a broken via on solderside:
Patching it restored graphics, MASK ROMs check successfully performed now:
As for lack of sound I quickly pinpointed the fault in a 2k x 8bit static RAM @E6 (connected to Z80 audio CPU). piggybacking it restored sound.Once removed I had confirm it was really bad :
PAL UpdatesComments Off on Contra and Pac-Eight PAL dumps added
Nov222017
Today we have new PAL dumps :
Contra.
‘coolmod’ sent in 256KB binary dump of the secured PAL16L8 from an original Contra PCB, I took care of reversing it in a GAL16V8 fuse map that he successfully tested on board.This dump replace the old archive we had.Thanks to him.
Pac-Eight (a Namco Medal Game)
PLDs (all GAL16V8) have been dumped by Rod_Wod of Dumping Union mailing list from this board:
We mark them as ‘assumed working’ since they have been obtained from unsecured devices.Thanks to him.
Maybe many of you will recognize this IC and throw up hands in horror:
This is the ‘infamous’ ‘HB-41’ used on several arcade PCBs (from Seibu/TAD Corporation but not only) :
Raiden
Blood Bros
Legionnaire
Sky Smasher
Toki
Dynamite Duke
Olympic Soccer ’92
Cabal
Heated Barrel
Operation Wolf
This analog component (20 pin SIL package) is used in sound circuit to mix background music and sound FXs as well as it acts as filter of both.From my experience (maybe also others can confirm it) it’s a prone to failure part.Let’s take a look at what is inside it:
As you can see from above scan the custom is built around two ICs : a dual operational amplifier and a quad operational amplifier.All the rest are resistors (also printed film ones, the black squares), ceramic and tantalum capacitors.In order to reproduce it, after removed the epoxy, I pulled all the parts and metered them then I drawn schematics which then I routed ending up in a 5.3 x 1.8cm PCB:
More or less same dimensions of original part:
Here is how it looks assembled:
I used an LM358 and LM324 for my testing which maybe are not the best solution since the original OP-AMPs have both high gain bandwith (10MHz) but the replacement works well on all PCBs I tested so far.Here is testing on a Cabal, Blood Bros and Toki PCBs:
PCB Repair LogsComments Off on Thunder Cross II repair log #2
Nov102017
I had on the bench this Thunder Cross II PCB by Konami:
Many components were removed from the board : one WORK RAM @12D was missing and the other one @11D cracked in half, also the ER5911 serial EEPROM was not there :
The two tilemap RAMs @17H and 18H:
Some electrolytic capacitor in audio section:
The 3.58MHz oscillator @9K (it generates clock for whole sound system)
Also the RAM in sound section was almost desoldered, indeed it came off easily:
With patience I installed all the mising components and powered up the board :
At closer inspection the above error was caused by a broken trace between pin 21 ( address line A10) of the two 6264 WORK RAMs, I promptly patched it:
Now the board went to intial self-test showing two bad devices, both related to sound system.
The one @4F is the ROM containing code of the Z80, the one @5F is its 2K x 8it RAM (previously replaced by me)
Both were verified as good so problem was elsewhere.Sound system is made of a Z80 which commands a YM2151 FM synthesis chip (used for music) and custom marked’053260′ which plays ADPCM/PCM samples.Lalsty BGM+ samples are sent to a YM3012 DAC which outputs analog sound them amplified by OP-AMP and amplfier.When I probed the YM2151 I found that PIN 21 was dead:
This pin is the serial data output :
I pulled the chip:
It was really bad but also replacing it I still got the error @4F and 5F on self-test.YM2151 datasheet says that in typical application pin 21 is tied to YM3012 but on this board it’s tied to the custom ‘053260’ and then from this to serial data input (pin 4) of the YM3012 DAC.So the ASIC was likely bad.Time to remove and replace it:
Finally board got past the self-test and entered in game with full sound:
But, as you can see from above video, sprites were all garbled.MASK ROM check reported two bad 4Mbit devices @3K and 7K :
Using a logic probe revealed that two address line (pin 6 ‘A3’ and 39 ‘A9’) of both devices were stuck high:
These devices are directly addressed by the ASIC ‘051960’ (working in pair with ‘051937’ which reads data) which from my eperience is not really reliable.So I replaced it:
But I was wrong.At this point, after check as good all connections, it was clearly obvious that the two MASK ROM were bad.Indeed, once removed them, they both failed in same address lines when I read them in a programmer:
I replaced them with two pin to pin compatible 27C400 EPROMs and MASK ROMs check no more complained:
This project started when, during my repairs, I came across these two PCBs.
Blood Bros:
Raiden:
Both were faulty.Blood Bros played blind :
While Raiden lacked of the BLUE color:
The culprit was the same in both boards, the ‘UEC-52’ (sometimes silkscreend on PCB as ‘HB-52’):
It was clearly faulty in Raiden and missing at all in Blood Bros:
This custom in SIL package is an RGB DAC responsible to convert the digital signals of color palette circuit into analog, it’s used on some Seibu/TAD Corporation PCBs like :
Raiden
Blood Bros
Sky Smasher
Some time ago I partially figured out the pinout and schematics/parts after removed some of the epoxy resin that encapsulate it :
As you can see it’s a 15 bit DAC whose design resembles the Taito ‘TC0070RGB’ : two octal D-type flip-flops , some printed film resistors forming resistor ladders before the output to JAMMA RGB pins.But there was also a third IC that I could not identify.At first glance I thought about some kind of darlington array to amplify the signals so I made a post on EEVblog asking for some help:
The user ‘stj’ (thanks again to him) pointed me in right direction suggesting that the unknown IC could be a 74LS367 used for video blanking.So I removed the IC from a working custom and was able to identify it as a 74HC368:
At this point I had all the info to complete my schematics in order to design a replacement, obviously I first made some prototyping on breadboard which went fine.Later I sent my project files to China for manufacturing and got the bare PCBs after some weeks:
Time to populate (in my design I used 74HC574 since it has more logical pinout compared to 74HC374)
Here is a side-by-side comparison:
Testing was successful on both boards (excessive brightness of recordings is an issue of camera, video levels are exactly the same of original part)
