Galaga Power Supply Issues

[ManiN]

Anybody had experiance in these? My future father-in-law picked up his first game yesterday. Nice condition complete galaga with a bad power supply. I looked at it quickly and found all components power up except the PCB. Looking at the power filter PCB, you can see burn and melting on the top pin of the connector coming from the main transformer below. Some power reads coming out of the filter board to the game PCB, but seem to be incorrect values. I didn't have a schematic at the time, but now I do, so I'll check further later. I did a continuity across the large ceramic resistor in the center to find it shorted with zero ohms.

I'm wondering if I any of you have seen this before, and how hard would it be to wire in a retro fit switcher. I understand bob has ready kits, but at $45, I'm interested in buying a switcher and wiring myself for a few dollars more. Any $20 costs I'm not anticipating and should just get the kit? This is assuming the PS is dead... I still want to make proper checks to verify this.

I'll upload a pic later.

Thanks!

 

[Dokert]

Dude! You really should make the drive up north and come see me.

The kit to fix the ps will run you roughly $30 from Bob shipped. It does not include the big white resistor. It sounds like in your particular case it is better to wire in a switcher, but it is hard to say without seeing the ps. Could just be that resistor that is bad, which can be fixed for a couple of bucks.

 

[BobsterD]

I'm in the "install a new switcher" camp. I have many Galaga's, and it's very simple to install. Plus, you'll (probably) never have a PS related problem again with it.

Install the switcher, set it for 5.2v across C1 on the CPU board and forget it.

Bob Roberts even sells a complete kit to make it even simpler for only $45. While you're in there, do a cap kit to the board.

 

[ManiN]

Haha!

I think I'll lean towards a switcher. I've heard those PS's are crap and should just be updated as soon as they fail anyway. Why is bob's kit so expensive? Seems I can just order matching connectors and some wire to make my own... It's almost like he's punishing lazy people for not wanting to make it?

I have a feeling a transistor or something similar failed and shorted out destroying the ceramic resistor and loading the pin on that input connector till it melted all the solder away.

 

[KenLayton]

Put a switcher in and sell your old power supply board to offset the cost.

 

[Dokert]

It's almost like he's punishing lazy people for not wanting to make it?

Nailed it.

You don't need the connectors or extra wire, all you need are a few "U" spades and a switching power supply.

 

[ManiN]

Check this out. It's only $39! I must say that is pretty clean...

 

[Dokert]

Check this out. It's only $39! I must say that is pretty clean...

That would be the ArcadeShop version.

 

[BobsterD]

Check this out. It's only $39! I must say that is pretty clean...

True... but if some of your problems are in the harness side of the plug, you'll still have them.

 

[ManiN]

True... but if some of your problems are in the harness side of the plug, you'll still have them.

So bob's kit is a complete solution from the main transformer all the way to the PCB? Does the arcadeshop version only tap in to provide the +5v etc.?

Is the old PS still used for some sections? On the schematic I see references to audio.

Thanks

 

[Dokert]

So bob's kit is a complete solution from the main transformer all the way to the PCB? Does the arcadeshop version only tap in to provide the +5v etc.?

Is the old PS still used for some sections? On the schematic I see references to audio.

Thanks

They are both pretty much the same, and are all that you need.

 

[BobsterD]

So bob's kit is a complete solution from the main transformer all the way to the PCB? Does the arcadeshop version only tap in to provide the +5v etc.?

Is the old PS still used for some sections? On the schematic I see references to audio.

Thanks

Dokert is right, both kits are basically the same. What I'm saying is just get the new PS and cut the harness/plug and hardwire the harness directly to the new PS. This eliminates any (potential) issues with the connections inside the plug.

 

[Dokert]

Dokert is right, both kits are basically the same. What I'm saying is just get the new PS and cut the harness/plug and hardwire the harness directly to the new PS. This eliminates any (potential) issues with the connections inside the plug.

Yep only $26 for the ps.

 

[ManiN]

Here's a shot of the problem child:

 

[Dokert]

The AC header on the bottom is burnt pretty good. Both the connector and the header would need to be replaced.

Test all of the diodes on the board, and see which ones are Bad.

 

[ManiN]

D101 and D102 maybe?

There is also signs that someone hardwired something right to those last pins where the burning is at some point in time. The previous owner said it just stopped working, so believing that, I'd say it was from long before. Not sure what they'd want to hook up there?

 

[ManiN]

Looking at this schematic I've circled the leads I would figure would needed to be removed and hooked into the switcher. Are there any I'm not thinking about. What should I do about the 7.2V? Should I leave the J1 plugged in, or remove all together? What is the audio impact by removing the old PS?

Also, can I get a recap on the purpose of -sense?

Thanks for insight & help!

 

[BobsterD]

Go here -

http://www.arcadeshop.com/gal-tips.htm

Then scroll down to the "install switching power supply" section, it will tell you what wires go where.

 

[ManiN]

Very cool! I'll let you guys know the end result!

Thanks!

 

[ManiN]

I forgot to reply, but the posted method worked great. I do hear a speaker hum, and am not sure if a filter was bypassed or what?