I need a little help with My Galaga PS if I'm going to keep it

Jlannoo

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I need a little help with My Galaga PS if I'm going to keep it

I cleaned up and fixed the connections at the hot spots shown but that area is still getting hot. pin 12 on the J1 connector looks a little toasty too but the board is fine there. Ignore the dangling cap. I took that off for now.

As is I am only getting 4.6 to 4.7 volts with the adjustment cranked all the way. Some considerable noise/tone as well.

The fuse holders in the bottom of the cab are pretty shot though the voltages seem ok. I'm going to replace those.



photo+_9_.JPG
 
I cleaned up and fixed the connections at the hot spots shown but that area is still getting hot. pin 12 on the J1 connector looks a little toasty too but the board is fine there. Ignore the dangling cap. I took that off for now.

As is I am only getting 4.6 to 4.7 volts with the adjustment cranked all the way. Some considerable noise/tone as well.

The fuse holders in the bottom of the cab are pretty shot though the voltages seem ok. I'm going to replace those.



photo+_9_.JPG

there are not too many parts to replace on that board. I would get some spare regulators for that with the order just to keep as spares if you don't replace them. Don't forget to get the heat compound for the heat sinks as well as spare diodes.
 
Why is it getting so freaking hot there tho. those parts have good connections now. I have a feeling they actually desoldered themselves when they were loose. I don't mind replacing everything if I have too.
 
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Caps in power supplies often become noisy when they are bad. The cost of those large capacitors is going to be quite substantial, going for a switcher would probably be a cheaper and better solution.
 
Caps in power supplies often become noisy when they are bad. The cost of those large capacitors is going to be quite substantial, going for a switcher would probably be a cheaper and better solution.

the larger is around $23 the smaller around $10
 
Yeah I asked about a Twisted Quarter switcher kit. Its cheap but only connects to the aux power molex on the Game PCB. I asked if that was sufficient but didn't really get a reply.


I really don't mind fixing this either. I don't know why that section is getting so hot. The diodes seem fine. Fuse holder has a good connection etc. I'm at 4.7 volts so I'm close.
 
Ok let me try a different approach. The giant .02 fared Cap connects at one end inbetween the diodes to the left of the f2 fuse. While not as noticeable. That cap is burned a bit too at that connection. Cpuld it be just that cap causing the heat issue. Is there a way I can find if its super bad with a multi meter?


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Yeah I asked about a Twisted Quarter switcher kit. Its cheap but only connects to the aux power molex on the Game PCB. I asked if that was sufficient but didn't really get a reply.


I really don't mind fixing this either. I don't know why that section is getting so hot. The diodes seem fine. Fuse holder has a good connection etc. I'm at 4.7 volts so I'm close.

Part of the problem is you are pulling the same current but at a lower voltage. Ohms law comes in handy but to make it more simple; as the voltage goes down the current goes up. Throw a little resistance in there, like a dirty connector, and you get more problems. You probably have bad, dried out caps from that heat and a weak voltage regulator. You have to decide to repair or replace.

The other answer to you question;

I usually use the pcb edge connector and the aux connector for testing. I would not use just the aux connector.

Whatever you decide will have it's own rewards and cost.
 
Ok let me try a different approach. The giant .02 fared Cap connects at one end inbetween the diodes to the left of the f2 fuse. While not as noticeable. That cap is burned a bit too at that connection. Cpuld it be just that cap causing the heat issue. Is there a way I can find if its super bad with a multi meter?


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You will need an ESR meter if you will be doing much repair work.

http://www.ebay.com/sch/i.html?_fro...1313&_nkw=esr+meter&_sacat=See-All-Categories

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It can be that cap causing problems and should be tested to be sure.
 
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If you decide to pop for a ESR meter, monitor repairs will become a snap. I can use my in-circuit cap meter and use have of the caps or less in a typical cap kit to fix a monitor.
 
Hewitson said:
Caps in power supplies often become noisy when they are bad. The cost of those large capacitors is going to be quite substantial, going for a switcher would probably be a cheaper and better solution.
the larger is around $23 the smaller around $10

Huh? Where are you buying caps?!?!

Large one, $2.78

http://www.mouser.com/ProductDetail...EpiMZZMukHu%2bjC5l7Ycd/H5%2bMxIQf06snKyUCsuM=

Smaller one, $2.67

http://www.mouser.com/ProductDetail...=sGAEpiMZZMvwFf0viD3Y3ROGmxq83YAGRJ2bEx4qmV4=

-Ian
 
That is ridiculously cheap... I've probably wasted a lot of money on caps over the years but I'd much rather go around the corner to get them than have to wait a week or two for them to arrive in the mail.

Can't say I've ever heard of a snap-in cap, what a stupid idea.
 
That is ridiculously cheap... I've probably wasted a lot of money on caps over the years but I'd much rather go around the corner to get them than have to wait a week or two for them to arrive in the mail.

Can't say I've ever heard of a snap-in cap, what a stupid idea.

guess I could just solder leads on.

Noticed the one snap in is a .022 Farad and not a .02 will that matter?
 
I'd suggest trying to "snap" it in and then solder it, you shouldn't need to solder any leads on. Personally I'd try and get a standard one.

.022F will be fine.
 
Can't say I've ever heard of a snap-in cap, what a stupid idea.

New to this whole "electronics" thing, huh? :D Snap-in caps are nothing more than capacitors with short, stubby leads that are thicker, and have a bend to them. They are unbelievably common in power supply applications. The advantage is that the snap-in legs provide some mechanical stability so that the solder joint isn't the only thing holding it to the board. They are not a "stupid idea". Older designs had a third leg (an extra common terminal) to provide this stability. That was kind of silly.

In our application, however, simply solder wires to the terminals. The snap in terminals are really easy to wrap a wire around and solder to.

-Ian
 
guess I could just solder leads on.

Noticed the one snap in is a .022 Farad and not a .02 will that matter?

Yeah, solder wires to it, and zip tie it to the board.

20,000uf is an obsolete value and not commonly used anymore. You'll pay a premium for one, and it just doesn't matter in this application (a filter cap after a rectifier). You can go a fair bit higher in capacitance and it really won't make a difference, if anything, it'll filter a little better. Not to mention, the tolerance on those old electrolytics was pretty bad. Even new ones are usually 20%.

Also, axial lead capacitors themselves are pretty obsolete. More modern form factors for large filters are the snap-in type, or leaded radial. Even smaller caps are harder to find in axial. You pay a premium for those too.

In our application, though, especially in a board this simple, it just doesn't matter. By using modern capacitors, you'll save a lot of money, and you're also very likely to get fresh stock (I've bought axial caps from a distributor that had date codes from 20 years ago. The caps were only a year or two newer than the faulty ones I was replacing!)

-Ian
 
Here's a page Bob did on subbing radial caps...

http://www.therealbobroberts.net/90411.html

Regarding the OP's issues.....replace the caps, check/replace the headers (especially if they show signs of heat), check/replace the connectors inside the cabinet (especially if they show signs of heat....not a bad, regardless, they're probably worn out), remove the two big diodes in the heat zone, remove all the old solder, polish the legs of the diodes with some fine sandpaper, reinstall (or replace....they are cheap, but yours are fine). Polishing the legs will insure a good solder connection.

Edward
 
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