Bubble Bobble not working correctly with Sega Blast City

[firebird]

I got a problem that makes it hard to sleep...

I got a Bubble Bobble pcb (orgininal). This board has not the standard JAMMA connector on the board but rather three connectors and needs a special adaptor. Anyhow that is OK, I got an adaptor, and and when I hook it up to the supergun (raijin) it works just fine. However if I connect to the sega blast city candycab the picture almost get totally black, and I can only seem some outlines of small gfx.

Running other games on the blast city works good. Pic from the blast city:


I tried changing the harness going from the attached PCB within the cab to the game PCB. No luck/improvement.

Writing this down should help with the sleep problem

But any tips or advice from you folks is appreciated, thanks.

-Firebird

[system11]

On the JAMMA adapter, at the JAMMA edge side, run a wire from pins 1+2 (ground) to pin 14 on the parts side, which probably isn't hooked up to anything at the moment. That's video ground, your cabinet needs video ground but due to the wiring in your supergun, that doesn't. It's a very common problem.

[Moteuchi_Yota]

Same problem with my egret II and super neo 29. Problem solved with this trick (wire from pin 1 to 14, parts side). It's also possible to have another problem: the game not takes credits. In that case, wire a random button between pin 16 and 1 (or 2, or 28), and press that a lot of times for credits.

[firebird]

Hmm, it doesn't seem to help. I wired on the adaptor as shown here:


The picture is identical to my first post with this connection. Did I misunderstand?

Thanks for the help!

[system11]

You did exactly the right thing - also I note pin 14 was wired up already anyway.. Have you tried wobbling the adapter-cab connection whilte it's running or cleaning the edge connector?

It's just that your screenshot shows the classic signs of missing video ground, but you already jumpered common ground correctly on the adapter, and the adapter was already wired for it. Do you have a multimeter?

[firebird]

I do have a multimeter, yes. I will try to do some wobbling and check/clean the connectors.
Edit: I don't think the problem is within the connector.

[system11]

It may not be, but it needs ruling out. Quite often those fingerboards of the type you have on that adapter oxidise and make poor contact. I usually cut them off and replace with newer types if they won't clean up. I assume you very recently checked another game in the cabinet too?

If the answer is yes and they're fine, then we know the cabinet is definitely OK.
If the game displays fine on a supergun we know the game is definitely OK.

However, from your photo - that's a video ground problem, no doubt about it. The supergun is probably ignoring the supplied video ground and doing it inside from a common ground feed (they shouldn't, but you see it a lot). What happens if you disconnect the black wire which is on pin 14 but leave the ground jump you added installed? With your meter set to continuity test and the adapter plugged in (game turned off), do you get continuity between pin 14 on the adapter side, and pin 14 on the JAMMA connector side in the cab?

[firebird]

I tested a another board (newer one), and it works just fine in the cabinet.
I tested bubble bobble on the supergun again, and the picture looks good.

I disconnected the black (orginally on pin 14), but the let added wire in place between 1 and 14. The game then came up exactly as with the black wire connected!
So it appears the black wire did not have a function. I also tried to connect to pin 14 with power on, but nothing happened, picture remained unchanged.



Testing continuity over the connector on pin 14 gave a beep, the connection is OK.
Testing from the pcb to the black wire also give continuity.

Hmmm......

Edit: Also tried connecting pin 14 to the ground on the other side of the connector (it shouldn't make any difference), and no change happened. But..... If the supergun manages to do the signals right, there should be a way to make the cab also work! Maybe a beer helps on thinking...

Edit2: I did a major find I think. Voltage... When using the supergun it provides -5V on the pin it is supposed to. The cabinet however gives nothing. I have feeling that is important when reading other places. Seems like the powersupply within the cab cant provide -5V... Dang

[system11]

That was going to be my next question, it seems an unlikely reason since -5v is *usually* only related to sound circuits and Bubble Bobble does need it... So I downloaded the Bubble Bobble schematics, but the copy online is so bad that loads of '+5v' look like '-5v' and I gave up without a clear copy.

There's an easy way to test - put the adapter back how it was (I could tell from schematics that the black wire on pin 14 JAMMA was connected how it should be, it's tied to ground on the PCB). Then use a micro screwdriver to release the blue wire from the voltage connector on the other side of the loom. OBVIOUSLY INSULATE THIS, bit of cardboard, some tape, anything to stop it touching during test. If it then does the same thing on your supergun, -5v was the problem.

Unfortunately there's no real solution here - I was going to link you to a device called a Negatron which allows you to add a -5v supply to cabs that lack one. See for yourself the note about 500ma and Bubble Bobble:

http://wiki.arcadeotaku.com/w/List_of_J ... e_-5_volts

[firebird]

Yes, it seems to be demanding on the -5V... I was thinking about rebuilding the entire PSU of the cabinet. But I think could be a big task. It seems the blast city needs 3.3V, and a PSU as in the link below does not have it:
http://www.jammaboards.com/store/16a-ar ... 9916a.html

Anyway, thanks for the excellent technical advice and help in general

Edit:
Trying this (from the Negatron datasheet) could also be an option:

Overcurrent behavior
If the current limit has been slightly exceeded, th
e output ripple will substantially increase and
oscillation may occur. Adding extra output capacita
nce (1000uF) can sometimes help in
applications where you are just over the limit of w
hat Negatron can handle. When the current limit
is substantially exceeded, Negatron will gradually
bring the output voltage closer to zero to try to
protect itself. As with any electronic component, k
eep within the recommended operating
parameters to ensure long product life.

Edit2:
What about 2 negatrons in parallell, set with the same setting?

[firebird]

What does it do? Nibble your bum?


Nope it does this:


Attached it to the taito adaptor like this:


And voila, at least an improvement in picture quality:


Overall the picture looks great, but there is a little noise or something on the signals, as the picture is a little bit flimsy (I'd say). When not running a PCB the modification provides -5V nicely, however when running bubble bobble it drops to -0,7V on the -5V terminal. Not sure exactly why, as the unit (tps84259) is supposed to deliver up to 1.5A @ -5V. But it could be I'm using to thin wires also somewhere.

Next step could be to do some current measurements maybe.

Anyhow, really nice to have to some progress

UPDATE:
I think I found a solid and durable solution:
Bought a new chip, which was easier to solder, and with higher capacity. I also added overcurrent protection. This unit is now running the game providing -5V nicely on the terminal.

The chip is a TI one: PTN78020A Series http://www.ti.com/lit/ds/symlink/ptn78020a.pdf

-firebird

[8bitForLife]

Sorry to necro an old post but I'm having same problem. No coin and same picture as in post. I'm kinda dense but is all I need to do is add a negatron and picture comes back and sound and coin? Or do I need to do the sync stuff to.