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Vanløse, Copenhagen, Denmark
Mathematician. Working programmer/system developer. Nerd. Married. Father of 3.

20.12.14

Taito Asuka & Asuka Repair Log

This original Taito Asuka & Asuka


I was lucky to grap real cheap on a Danish forum. The guy selling it didn't post a picture of the PCB, misspelled the name of the game, and stated that it might be a bootleg. So even though it was an auction, this game went under the radar of other forum users, and I got it for my initial cheap bid. As I later on discovered that this seller is a dirty rotten swindler, I don't feel bad about it.
Anyway, when I first received the game, it played well and was all working and fine. I decided to bring it with me to an SSKT-gathering in Næstved Denmark, as one of my friends there wanted to try it out. I don't have a car myself, so when I'm not able to get e lift with someone else, I travel by train with all my gaming goodies in a suitcase and/or backpack. Sadly Asuka&Asuka didn't quite survive the trip fully functioning. Some of the colours were frakked up


and I didn't have the time on-site to have a look at it. Upon returning home, it was just shelved, until I had a time to look at it.
Months later I decided to have a go at fixing it. I soon discovered, that this PCB suffers from the same Achilles Heel, as many other Taito games from the same period; the Taito SIL-RGB-module


And having a closer look, I could also see, that a reflow from the component side had been attempted earlier on. I found that pressing down on the package made the error go away


so I was pretty confident, that I was on the right track here.
Besides that, I also found a large cap on the loose


but I was rather sure, that this was not involved in the colour issue, so went straight on to the RGB-module.
Taito used these type of custom SIL-RGB-modules on a number of their games including i.e. Rainbow Island back in the day, and always mounted them perpendicular to the PCB, instead of making sufficient space on the PCB and bending it down onto the PCB surface. That way it's extremely flimsy and very sensitive to just the slightest bend or bump.
As an initial attempt, I tried doing another reflow from the component side, but without any luck. So I decided on desoldering the thing and mounting it properly. But when I started and gave it just i little yank while desolering, all the pins snapped clean off }:-O



I had a lot of 64-pin reduced size DIL sockets, that I bought as a mistake some time ago (wanted to use them for socketing 68000 CPUs, but didn't look closely enough at the pitch }:-S Luckily they were cheap };-P), and I decided to use 2 of these on top of each other top mount the module properly. The bottom would be soldered to the PCB, and the module would be mounted in the top one. That way the module would rise above the other components, making it easy to mount it flat.

But first the holes needed cleaning; all the old component pins were still sitting there. That proved to be a harder task than expected. Most of the pins came out pretty easy


but the holes for the 4 supply pins (2 x 5V and 2 x GND) had their vias connected to big supply planes inside (middle layers) the PCB making it very difficult to heat up the solder blobs. Also I think the supply pins themselves might be slightly thicker than the others, because they were just stuck! After having cleaned all the other holes and also broken a track on the solder side }:-S


I gave up on those 4 last holes; 5V and GND was no problem getting elsewhere nearby on the board. So I started working on the socket to be soldered onto the PCB. As there were other components on the board where the socket should be placed, I needed to cut some of the plastics so it would fit around them


I soldered some small wires on the supply pins of the socket, and also removed a bit of lacker from a big GND plane on the PCB with my Stanley knife, where the bend pins on the "other" side of the socket could attach.


I soldered in the socket connecting GND to the big GND plane "inside" the socket "walls", and 5V to a nearby cap. The pins on the "other" side got soldered to the PCB as well for proper fastening.


As a last preparation of the PCB, I replaced the electrolyte cap for an equivalent one with a smaller form factor


Now on to the top socket. I started by soldering pieces of uninsulated single core wires onto the pin-stumps on the module and then cutting them down to equal length. I then pressed the wires firmly down into the holes and caryfully bent the whole module down onto the socket


I then used hotglue to secure the module to the socket from the underside


I inserted the top socket into the other... a perfect fit };-P


After having fixed the broken track on the solder side with a piece on kynar


and reflowed the the loose cap


it was time for the big test. And lo and behold...


We have all colours back again! };-P And you can tap on, wiggle with, press down on the module etc., and the colours still stays on };-P

This game is a nice little vert shmup, but I am considering parting with it, cause the very weird sidescrolling used, kind of makes me a bit seasick when playing it };-P

23.11.14

Capcom Ghost 'n Goblins Bootleg Repair Log

I snapped up this defective bootleg Ghost 'n Goblins along with some other defectives very cheap at a danish forum about a year ago. Up until now, it had just been sitting on the shelf; not even tested. It had adaptor wires soldered directly onto the edge connector.


As mentioned before I believe, that people who does these kind of things, will burn in a special level of Hell; the one they reserve for child molesters and people who talk at the theatre... The Special Hell! }:-(
Well, anyway... the fingerboard soldered to the other end of the wires wasn't JAMMA, so I made a QAD adaptor with a JAMMA fingerboard connecting only the power and video connections. The game booted, and I was greeted with the attract mode:



The backgrounds and sprites were perfect, but the layer displaying characters and the game logo was pretty messed up and the game was dead silent. The silence could, however, just be due to a dip switch setting turning off attract sound.
I did the usual visual inspection, but as nothing obvious was to find, I started doing (what I sometimes refer to as) "Playing the game of peeking and poking around". For this, I use either my scope, logic probe or both. The purpose of this, is to give me a rough idea of where the different elements of the game are generated. I usually start with the ROMs and RAMs trying to short adjacent data and address lines with the probe to see what that stirs up in the game. Also I peek a bit at the data and address signals. This time I started with the logic probe and quickly found that this ROM


and this RAM


both at the primary PCB (also containing the primary CPU, program-ROMs and the entire sound system) were definitely involved in making the character layer.
Next I went over all the data and address signal lines of the two with the scope, but didn't find anything unusual. But then these two these two guys


sort of in the middle of the ROM and RAM caugth my attention. Why just them you might ask? Well because they are Fujitsus, and Fujitsu TTLs from around the 80'es, just have a tendency to go bad at the moment. So they are all Usual Suspects when repairing PCBs from that period. In general this board is peppered with Fujitsu TTLs, but these sort of sat there in the middle of this cluster of non-Fujitsus and happen to be in the same area as the RAM and ROM. The 74LS86s are packs of 4 XOR gates. So again I tried to short some of the signal pins and found, and when I shorted pin 8 and 9 on the right of the twins


the character layer changed to this



Hmmm, all the letters displayed correctly, but upside-down. Then tried flipping the dip switch to flip the picture


and when shortening the 2 pins again got this


Perfect character layer. Ha! Haaaaa! Surely on to something now };-P I peeked the inputs and the output of that gate



and found one of the inputs floating. I traced the input to the output at pin 8 on the left Fujitsu 74LS86. I salvaged a 86 from a scrap board, piggybacked it on the left one


And got perfect character layer with both orientations };-P



So out it went.


In my eager I accidently pulled out a via with it, but luckily it isn't connected to anything on the component side, so no worries. A socket was fitted and the salvaged 86 installed.


So now the graphics was a'okay... time to clean up that edge-connector-mess! With a combo of soldering iron, desoldering iron, solder wig, a whole lotta patience, and a final rub with rubbing alcohol


it actually ended up looking pretty okay in the end. I attached my full Capcom Classic adaptor and booted her up; but alas, no sound. So I dug up my external amp. It's actually just an old PC-speaker, where I've cut the jack plug and attached a crocodile clip for GND and an old multimeter probe for signal (actually it also good for listening on signal lines as well). Anyway, I heard sound from the speaker


Followed the sound to the fingerboard and found, that this was again a game that uses SPK- for signal and SKP+ for GND. As my SuperGun uses SPK+ for signal, that was why I didn't get any sound. So I finally pulled myself together, and installed a switch to flip the polarity of the sound in my SuperGun.


...better late that never, right };-P This closes the case...

Plz take care all you lovely people out there!

<3 Whole Lotta Love <3
};-P Elgen

4.10.14

Taito F3 Motherboard Repair Log

Finally BACK! ...from a faaar too long pause };-P
This little repair was done on-site at a gaming gathering I attended in Næstved. My friend m1chelsen, who runs a youtube channel and a blog about gaming and game collecting, has made a very nice looking consolization of a Taito F3 System. The motherboard he had gotten for free, as it might have some trouble with the controls. Also, he didn't have any games to actually test it with, so he brougth to the geeky gathering, where some other people brought their F3 carts.


It worked! ... or let's say, it almost worked. It booted up perfectly, but the down direction for player 1 wasn't responding (and Elevator Action Returns really isn't that fun without). Luckily I'd brought some basic tools with me ... just in case };-P
So after m1chelsen had freed the motherboard from the nice wooden casing


I started debugging. I followed the trace from the player 1 down pin on the fingerboard and found, that all the control inputs ends in some opto couplers (the 2 rows of white ICs; haven't really seen that before on an arcade board).


After googling the data sheet


I found that the LEDs inside have one end connected to Vcc via resistorarrays; the other end goes directly to the fingerboard. When the control is activated, the link to GND is made and the LED lights up activating the corresponding photosensitive transistor in the IC-pack.
I tested the relevant resistorpack with the multimeter


and found, the resistor for player 1 down direction broken.
Now we didn't have any spare resistor packs at hand nor a single resistor to patch on, and we wanted to play it like frakkin' now! So what to do? Hmmm think McFly, think!

....DING! (the sound of Elgen getting one his crazy ideas };-P)...

Okay, the reasoning goes like this: Due to the very physical nature of a joystick, you can never activate both up AND down at the same time. So if I connect the down-LED to the up-resistor of the array as well, they will never "use" the resistor both at the same time. So no risk of drawing too much current. I soldered in a small jumper wire on the solderside of the board


... and BAM! Dear m1chelsen was now able to ride the elevator down in Elevator Action };-P
The motherboard was put back into the nice wooden case and was played several times during the weekend. This closes the case };-P

More blog posts is on it's way soon ... promise! Also remember, that you are also able to follow ElgensRepairs via Facebook, Twitter, Instagram.

<3 Love };-P Elgen <3