My friend Alexander sent me this original Sega Out Run PCB for a repair:
After adapting it to JAMMA I powered it up and I could noticed the defect :
There were some dots on the screen in which I could recognize parts of sprites (lile a ghost images, I’d say).Since video board is the lower one, I could not reach with my logic probe or scope the involved circuitry made of the 315-5211custom Sprite Generator plus sixteen 62256 SRAMs chips :
RAM test was successfully performed but didn’t cover all the chips :
So I went to piggyback each RAM chip and when i did it for the one @IC71, the issue was cleared:
Time to remove the chip and install socket:
Obviously the desoldered chip didn’t pass the test on my programmer:
Another double Tube Panic PCB repair, with this so far fourth are the PCBs I repaired for my friend ‘robotype’ (you can find here the first log).Let’s start with first one :
As label said, sprites were totally missing:
Sprites generation circuitry is located on the video board.ROMs were all good so, due lacks of schematics, I went to test components with my HP10529A logic comparator.When I clipped a 74LS161 counter @E8, comparator reported troubles on all its output pins:
It failed the out-of-circuit test:
With a good IC fitted, sprites came back :
First board 100% fixed, let’s pass to the second one which was labeled with “BAD SPRITES” (it seems sprite issue is a common failure on all the Tube Panic PCBs) :
This was confirmed once powered the board up:
As in previous repair, I already knew where to look at.Sprites ROMs are located on video PCB in form of 8 2764 devices on a small piggyback board:
Data of these ROMs are latched by some 74LS273, when I went to probe with my analog scope the one @E20:
I found all outputs were bad compared to inputs:
The IC failed when tested out-of-circuit:
The sprites looked much better but still not perfect:
This is how it should be (MAME screenshot):
So I went to probe other ICs with my BK560A in circuit tester which reported trouble on pin 16 (output) of another 74LS273 @G9:
This was confirmed also by my scope, the output pin 16 was stuck low compared to its input pin 17:
Once desolder and tested out-of-circuit, the IC failed in that specific gate:
PCB Repair LogsComments Off on Chelnov – Atomic Runner repair log
Oct252015
Another board from my friend ‘robotype’ and another quick fix.
I got from him this Chelnov – Atomic Runner board :
It was stuck on this garbage screen:
Main 68000 CPU busses were silent, no activity.Between 68000 and WORK RAMs (two 62256) there were some 74LS245 for communication between data buses.When I went to probe the one @F11, its pin 19 (output enable) was silent.I traced back this to another 74LS245 @E10 :
I piggybacked it and board booted fine :
I removed the IC and tested it out-of-circuit where il failed (it was from Fujitsu manufacturer):
Board 100% fixed.
P.S.
For the uninitiated there is also an unreleased Sega Saturn port of this game (a copy has been afterwards located and disc image has been shared online).You can read more about here:
I recently repaired a friend’s dead Ikari Warriors PCB.
It had a black screen on boot with no sound.
This game is a bit tough to diagnose as it is composed of 3 PCBs mounted on each other. Fortunately I had another working Ikari Warriors PCB so I could swap boards in order to track which board(s) were faulty. Top board and middle board were tested ok on my working Ikari so, fortunately, only the bottom board was faulty.
Here is a picture of the faulty bottom board with the faulty chips I replaced in red. I’ll explain every step below.
1. There was something that was avoiding the game to boot on that board. First, in order to reduce the field of investigation, I disconnected each of the 3 connectors on my working Ikari to see when the game was booting or not. It was booting only with the two bottom connectors on, the one above is only related to the sprites and doesn’t prevent the game to run. So I needed to focus on and around these two bottom connectors. I checked the signals on every pins to track a possible missing signal. After comparing the signals, I found one that was “floating” on my faulty board and was pulsing on my working board. This was connected to pin 9 of the 74LS367 (marked 1 on the PCB picture). Piggybacking a working chip on that one bring the game booting back again !
2. Well, the game worked but the characters had missing legs and were always looking down whatever movement you did, enemies had wrong visuals and background scrolling was jerky…
As previously seen, the sprites are related to the upper connector. I started to check the signals on the upper part of the board and quickly found a 74LS273 (marked 2 on the PCB picture) with a seemingly dead output (my working board confirmed this). Piggybacking the chip with a new one bring back the characters’ movements and visuals. I still had the jerky scrolling though…
3. This one took a bit longer as I had no real idea where to look on the board for the chip that was responsible of this jerky scrolling. After more than an hour, comparing signals between the working and faulty boards, I found a suspicious signal on a 74LS86 (marked 3 on the PCB picture). This was indeed a dead output (pin 6). Piggybacking a good chip on it bring back the smooth scrolling.
As an example, here is what the signal looked like on the pin 6 of that 74LS86 before and after replacement.
PCB Repair LogsComments Off on Frogger (Sega/Gremlin) repair log
Oct202015
Got this Frogger PCB from my friend Josef for a repair.Actually it was the Sega/Gremlin version which uses Konami Classic pinout (like Gyruss, Scramble and many others):
PCB played fine but had a strange issue where sound was very quiet on my supergun while was completely silent on a cabinet.All audio circuitry is located on upper board.Looking at i I could notice that someone had previously reworked (replacing it perhaps) the M51516L amplifier ending with break some traces and using some jumper wires to fix it:
Luckily schematics were available so I went to check every connection in this part of circuit.Everything seemed fine until I came across to something odd : PIN 6 (ground) of M51516L amplifier was intentionally jumpered to positive terminal of a 100uF 25V electrolytic capacitor (so both terminals was shorted to ground) :
while schematics showed it connected to collector of a transistor through a 1KOhm resistor :
