Build Your Own Arcade Controls Forum

Arcade Collecting => Miscellaneous Arcade Talk => Topic started by: Angry_Radish on May 29, 2007, 10:21:55 am

Title: Who is good at troubleguessing boards?
Post by: Angry_Radish on May 29, 2007, 10:21:55 am

Hi all,
I recently picked up a Space tactics cockpit ( http://www.klov.com/game_detail.php?letter=S&game_id=9683 ) 
There was a blown tantilum capacitor on the board

(http://forum.arcadecontrols.com/index.php?action=dlattach;topic=51525.0;attach=75927)


Replaced the cap, checked everything else and fired it up, only to see this:

(http://forum.arcadecontrols.com/index.php?action=dlattach;topic=51525.0;attach=76216)

There is also some sort of code being displayed on the CP, though there is no mention of any led codes in the "manual"

(http://forum.arcadecontrols.com/index.php?action=dlattach;topic=51525.0;attach=76214)

I'm using this manual http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Space%20Tactics.pdf , which isn't very easy to read the schematics, but so far I've doublechecked all the connections (had some busted wires to the cp, a couple pins out of the plugs, etc..)
Checked voltages from the ps unit and boards (5, 12, -5, and for some reason 6 and 6.8), and checked continuity from all wires to the board edge, all good.

According to the manual, once the processor initializes, I should see the motors center themselves, and a message onscreen after some colored flashes, and I see none of that. The picure on the screen is the same as the pic above, slowly shifting downwards..

Any thoughts on where to check next?

I suppose if this were a common machine, I'd have 50 people coming out of the woodwork telling me to check this chip or that board, but hopefully someone can give me some more ideas of where to look now:-)

Thanks in advance!
Cheers!  :cheers:

Title: Re: Who is good at troubleguessing boards?
Post by: Angry_Radish on May 30, 2007, 10:47:51 am

Anyone?
Need more info?

I'm planning on checking power on the board to the processor and maybe dusting off my logic probe this weekend, maybe that will shed some light on this.
 I could use any other suggestions though.. anyone seen this sort of pattern on the screen? Ram? Processor? timing? Anything?

Cheers!
 :cheers:

Title: Re: Who is good at troubleguessing boards?
Post by: ChadTower on May 30, 2007, 01:13:52 pm

I would first suspect any ICs in line with that blown cap.  Things don't just explode without affecting something else.

Title: Re: Who is good at troubleguessing boards?
Post by: BobA on May 31, 2007, 10:14:12 pm

If you have checked your voltages then my guess would be problems with the CPU and or RAM/ROM.  It looks like you have a video display which is just showing the contents of video memory.  Means maybe the CPU is not initializing or clocking properly so nothing more is shown.   At least you have a display not a blank screen.  Use your logic probe to check clock and other releated lines then see if it is addressing memory to start.

Check your circuit diagram to see if there is a start signal or a reset.

Title: Re: Who is good at troubleguessing boards?
Post by: Angry_Radish on May 31, 2007, 11:05:41 pm

Thanks for the replies!
I hope to have some answers for you after this weekend if I find anything! :-)

Title: Re: Who is good at troubleguessing boards?
Post by: northerngames on June 04, 2007, 04:42:48 pm

can you post a picture of it now that it is replaced and cleaned the black up a little?

Title: Re: Who is good at troubleguessing boards?
Post by: psik0tik on June 07, 2007, 03:21:16 am

Anything that would make a cap detonate like that is probably scrapable. You may be better off looking for a new board for it since the monitor and everything else works.

Title: Re: Who is good at troubleguessing boards?
Post by: Angry_Radish on June 07, 2007, 10:04:24 am

Not as easy as it seems, this is a fairly hard to come by game, plus all the parts (short of the eproms) are still available and the board is in good shape. I'm fairly confident I'll get it sorted out between my scope and logic probe, though a comparitor would be a nice tool to have...

The hardest part right now is testing the board with power supplied.
It's mounted on the side of the cabinet with not too much room to get in there, and the multiple edge connectors and crazy-short wiring harness makes it hard to do any testing for an extended period of time:-)

With it in the garage right now and the hot weather, I've been finding more and more excuses to work on my other cabinets in the nice, cool basement lately:-)

Title: Re: Who is good at troubleguessing boards?
Post by: ChadTower on June 07, 2007, 10:08:02 am

Take out the harness and make it longer.  Then you can just wrap the wires up with a tie when you put it back.

Title: Re: Who is good at troubleguessing boards?
Post by: Angry_Radish on June 07, 2007, 10:17:25 am

Not a bad idea!
I may have to do that, my back can't take much more:-)

Title: Re: Who is good at troubleguessing boards?
Post by: northerngames on June 07, 2007, 10:58:48 am

have you checked the 2 burned trace's in the picture above also if you follow the burnt trace on the right stright up to the brown circle it almost look's like the brown circles leg is toaching the end leg on the chip but it may supposed to be that way but I would check to see if there is solder on it or not too see if it belongs there like that or now also did you remove the black blob of burnt board and solder it to may be toaching the 2 points under the cap.

I was not sure if this was the before or after you fixed it picture above but if the one above is afterward I would clean the trace's or check them with a multimeter to se if they are still contacting or not.