Galaga fried all to hell...EDIT: FIXED!!!

[2600]

I should say your problem probably isn't related to the ripple, but I always take care of the Power Supply before working on any problems.  Just a habit.

Maybe I missed it, but you did install the new socket correct.

[Mauzy]

Yes I did change the socket. When you talk about the power supply, are you talking about the switcher, or are you talking about the power section on the board?

[2600]

Depends on the game.  If there is a separate power supply, I always like to make sure everything is ok first.  I've had enough problems related to power during debug, that I try to take that out of the equation first.  Most of the time the power supplies have never been touched.  Even with modern switchers I do this if I don't buy them new.  Some PCB's, like Pac-Man turn the AC to DC on the board so I check that out.  Most others PCBs don't really have a power supply section except for maybe a large decoupling cap or two and depending if the game is a keeper or not I replace those. 

[ChadTower]

Yep... good practice is to take care of the power supply first, connections second, logic third.  Do it out of order and you'll fix a lot of issues you haven't even found yet.

[Mauzy]

Hmm. I'll give my power supply a thourough check and I'll do a few more benchmark voltages today. School just got canceled (yay! no pre calculus final for two more weeks!) so I'll have some time to kill today.

[2600]

Yep... good practice is to take care of the power supply first, connections second, logic third.  Do it out of order and you'll fix a lot of issues you haven't even found yet.

Good call on the connections.  I always look at them as well.  I just had a 720 shipped to me and it's currently not coming up.  I know I could probably get it up if I adjusted the voltage, but I refuse to start adjusting voltages because the connectors have a hole burned through it (common on system2 games).  Once I fix those, then I'll look at any problems.

[Mauzy]

Anything burned would DEFINITELY tell me to look at the power supply...

[ChadTower]

Anything burned would DEFINITELY tell me to look at the power supply...

It's one possibility but not always the cause.  There are a lot of games, especially pins, where there is one particular connector that's just not rated for the current level.  Can't tell you how many pins I've seen where the GI connector is just disintegrated despite the power supply being good.

[Mauzy]

Alright. Now Ive gotten to where all I have is a lot of random numbers, blocks, and tones. Upon power application, the screen changes garbage, then hangs on just garbage. Every time I start is, its different. Ive checked voltages, they are fine. I tried a new power supply, same thing. I cleaned all the pins on all the custom chips and got slightly different garbage. I even tried removing all custom chips in various amounts and combinations and got the same garbage and crazy tones, so Im not sure if they are even related. Perhaps a processor problem? I know you guys are going to tell me to change the sockets, so which should I do first. I'd like to not shotgun it it first. Once I have it stable Ill go through and switch every socket one by one if It seems necessary. I will have pictures up in the coming days.

[channelmaniac]

Replace all of the ROM sockets and CPU sockets first.

Do you have another game that requires the Z80 CPU? If so, swap the CPUs out to test them.

A Pac Man or Ms. Pac Man is a good choice to pop the Z80 into if you have one.

If you have an EPROM programmer, check the EPROMs against ROMIDENT to see if they are good.

If all that checks out then check your 2114 SRAM chips.

If you give up, I have a couple of working Galaga boards here and can do a swap for your old board and a bit of cash.

RJ

[Mauzy]

OKAY! Just got this board set back from GLS1 electronics. A little slow on the communication and my boards came back smelling like a smoky bar, but the repair went fantastic. The problem I was having involved the Z80 @ 4J blowing out every couple weeks. You could replace it, and the game would run fine for awhile, but then the Z80 would once again go out. I tested the supposed bad Z80s in a working Pac board and they were indeed faulty. Greg at GLS1 left it on the bench for a few extra days and found that the 74LS367 @ 1J was faulty. I'm not sure how this would cause a Z80 failure every few dozen working hours, but he said it was bad and it seems to work now. Luckily there is a 90 day warranty on his repairs.

Best of all my scores were still saved in the Galaga Enhancement pack after all these months!

[channelmaniac]

Easy....

If the chip is faulty it could be drawing excess current from the CPU and blowing out the gates on one of its pins.

[Mauzy]

Oh. Well that makes sense.