Double Dragon boardset: BUSTED!

[MaximRecoil]

I took the board out to fix some broken points on the "rail" (see this thread), and now the board doesn't work. I don't see how anything I did could have caused the problem, but who knows?

When I turn the game on, there is a recurring popping sound, one every second or two, coming from the speaker, and each time it makes the popping sound, the LED on the power supply lights up a little. I tested +5v at the board pins and I'm getting nothing, except a little voltage each time it makes the popping sound (something like .1v). I tried a different JAMMA board in there and it works fine, so the cabinet can be ruled out as the problem.

 

[Oryk Zinyo]

Are you sure the rail only contained one trace? Sometimes the rail will have multiple traces ran side by side. Try testing for continuity from the +5vdc line to the ground.

 

[MaximRecoil]

Are you sure the rail only contained one trace? Sometimes the rail will have multiple traces ran side by side.

I simply duplicated the broken-legs section of the rail with the jumper wires. There were 6 holes that the broken-legs section of the rail was soldered to, and each of the 6 legs were broken. I cut off that section of the rail with tin snips, removed the old solder and broken leg sections from each of the through holes, and also removed the solder from the first unbroken leg of the rail so I could slide a stripped end of a jumper wire into its hole along with it (call that hole number 0). Then I ran the other end of the short section of wire to hole number 1, and put another stripped end of a short section of wire along with it into hole 1 and soldered it; and I repeated that until all 6 holes were jumpered.

Try testing for continuity from the +5vdc line to the ground.

You mean on the card edge pins? As in continuity between pins A/B and C/D? If so, then yes, there is good continuity there.

 

[Oryk Zinyo]

What I was saying is sometimes the rail legs alternate between two different circuits. In these cases one physical rail actually carries two (or more) seperate circuits. If this was the case then the board edge connector ground and +5vdc would now be hardwired. Check for continuity from pin A to pin C to see if the circuts are crossed.


You can also peel off the paper shielding from the rail you removed and look to see if there is one trace or more. Or you can check this with your meter by looking for continuity from each leg to the others.



Have you made sure you reseated all socketed chips as well as any edge connectors? Often when you pull a board to work on it you flex it in a way that causes things you are not working on to move...

 

[MaximRecoil]

I completely removed the jumper wires so the board was exactly the same as before, and the board works again. I am completely baffled. I checked, double checked, and triple checked, and those wires were functionally/electrically exactly the same as if the rail was completely in there with no broken legs.

Edit:

What I was saying is sometimes the rail legs alternate between two different circuits. In these cases one physical rail actually carries two (or more) seperate circuits.

Ah I see. That was the problem then, because underneath that paper on the rail there is more than one trace. I knew nothing about that. I thought it was just a solid piece of metal. I'm lucky nothing got damaged when powering it up.

 

[Oryk Zinyo]

Ah I see. That was the problem then, because underneath that paper on the rail there is more than one trace. I knew nothing about that. I thought it was just a solid piece of metal.

Yeah, that is something I should have mentioned when I first told you what it was. I was in a hurry and not thinking straight, so I just assumed it would be a single trace rail. For future reference I normally see single trace rails from early 80's games and dual trace rails from the late 80's. I don't think I have seen rails like these on anything newer than 1990.

 

[MaximRecoil]

Yeah, that is something I should have mentioned when I first told you what it was. I was in a hurry and not thinking straight, so I just assumed it would be a single trace rail. For future reference I normally see single trace rails from early 80's games and dual trace rails from the late 80's. I don't think I have seen rails like these on anything newer than 1990.

I can still use jumper wires to reinstate the full function of the rail, I just have to wire it differently. I looked at it and I can see how it needs to be done.

 

[MaximRecoil]

I took the section of the rail that I cut off and I soldered it back into its through holes (I cut a little extra off it so it wouldn't be intermittently contacting the other section of the rail). The broken legs just sat into the through holes a little bit, but it was enough to top-solder them, and it should hold fine unless it gets banged around (which I don't expect it will). I couldn't do that before I cut the broken-leg section off because the legs were broken off too high up so they didn't contact the pads.

Then I connected the two sections of rails with two short jumper wires, one for each of the two rail traces. The game is working fine and the rail should be fully doing its job now.