(Topic ID: 293438)

Should I worry about this bridge rectifier?

By Tomass

5 months ago


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  • 25 posts
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  • Latest reply 5 months ago by xsvtoys
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#1 5 months ago

This rectifier is mounted flush with the board. Should I worry about getting it off the board? I am not sure how long this game played like this. It was a project that I am finishing up. Thanks for any help.

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#2 5 months ago

My gut feeling is get it up off the board.

I think I'd be more worried about the bridge rectifier cooking the board than the bridge rectifier itself.

LTG : )

#3 5 months ago

I would lift it up real quick fo sho

#4 5 months ago

That looks like it is going to be a tough one. No room to even apply pressure.

#5 5 months ago

Any suggestions on the best way. I have a good iron and a little pencil iron. I could probably put a regular tip in the desoldering tool and have 3 heat sources. Or I am missing another way?

#6 5 months ago
Quoted from Tomass:

Any suggestions

Solder sucker and soldering iron.

LTG : )

#7 5 months ago
Quoted from LTG:

Solder sucker and soldering iron.
LTG : )

Ok. Wasn't sure if I could get it all. Thanks, I will do that.

#9 5 months ago

I have one but that might be better. I have a real nice pace desoldering tool, but the piston on the vac pump broke and I haven't found one yet.

#10 5 months ago

Thanks! Got it up off there. Thought it was going to be a major deal, but not bad at all.

#11 5 months ago

I would have left it well enough alone - that's just me though.

"If it a'int broke - don't fix it!"

"What me worry?"

Alfred (resized).png
#12 5 months ago

Yes ^^ -- the solder looks to be original (there is no flaking of the solder mask near terminals). Is it causing problems? If not, why replace it? If worried about the heat, you can add a heat sink to the bridge rectifier without pulling him off the board.

I'd be more worried about those radial caps getting old and leaking corrosive guts on the board than that bridge.

#13 5 months ago

I wasn't sure if it was original or replaced. It wasn't working when I got it. The machine that is.

#14 5 months ago

I’d be more worried about the other two bridges that weren’t fused at the factory. The ones that mount off board.

#15 5 months ago

OK -- do you have +12V and -12V coming out of the bridge?
You didn't state which game so I am assuming a System 7. +12V can be found at test point 3 and -12V can be found at test point 4 (meter ground at test point 2).
If original caps, I would examine caps at C7 and C8 for leakage. Either of those two going bad can kill power the the 5V regulator circuit. See if you can measure a doubled voltage at the cathode (banded end) of diode D1. D1 is above the relay. If not doubled, replace C7 and C8.

While you're there, take a look at C12 and make sure he isn't leaking.

#16 5 months ago

Umm. Don’t Timmy up your board. Bridges are hard. Don’t ask me how I know.

#17 5 months ago

No, it’ll void your warranty. It says so right there.

#18 5 months ago
Quoted from G-P-E:

OK -- do you have +12V and -12V coming out of the bridge?
You didn't state which game so I am assuming a System 7. +12V can be found at test point 3 and -12V can be found at test point 4 (meter ground at test point 2).
If original caps, I would examine caps at C7 and C8 for leakage. Either of those two going bad can kill power the the 5V regulator circuit. See if you can measure a doubled voltage at the cathode (banded end) of diode D1. D1 is above the relay. If not doubled, replace C7 and C8.
While you're there, take a look at C12 and make sure he isn't leaking.

Sorry, I should have been more clear. Game wasn't working when I got it but it is fully working now. I am redoing the headers for preventative measures but was concerned when I saw that rectifier. I got it up off the board now. I will swap out those caps as well. Thanks for taking the time to reply. I appreciate the help.

#19 5 months ago
Quoted from EJS:

I’d be more worried about the other two bridges that weren’t fused at the factory. The ones that mount off board.

Yep, I fix that before I turn on a sys 3-11 when I get them. 3-7, I swap out sockets and headers as well.

#20 5 months ago

That is a 35 amp rectifier handling only 7 amps. I doubt it even gets warm.

#21 5 months ago
Quoted from Schwaggs:

That is a 35 amp rectifier handling only 7 amps. I doubt it even gets warm.

No clue. Sorry

#22 5 months ago
Quoted from Tomass:

No clue. Sorry

Don't be sorry for not knowing, that is was why you were asking if you should move it off the board!

I was just offering up some additional information as to why or why not move it off the board.

#23 5 months ago
Quoted from Schwaggs:

That is a 35 amp rectifier handling only 7 amps. I doubt it even gets warm.

OK - curiosity got me.

KBPC35 series = 1.1V forward voltage drop per diode.
Two diodes always operating simultaneously.
Power = (2)(1.1V)(7A) = 15.4W
Defined thermal resistance = 1.4C/W
Temperature rise = (15.4W)(1.4C/W) = 21.56C temp rise. (rounded to 21.6)
Ambient = 25C typical so operating temp will be about (25 + 21.6) = 46.6C or 115F. Yeah, it will see a temperature rise but far from being too hot.

#24 5 months ago
Quoted from G-P-E:

OK - curiosity got me.
KBPC35 series = 1.1V forward voltage drop per diode.
Two diodes always operating simultaneously.
Power = (2)(1.1V)(7A) = 15.4W
Defined thermal resistance = 1.4C/W
Temperature rise = (15.4W)(1.4C/W) = 21.56C temp rise. (rounded to 21.6)
Ambient = 25C typical so operating temp will be about (25 + 21.6) = 46.6C or 115F. Yeah, it will see a temperature rise but far from being too hot.

Thanks Ed! Know we REALLY know!

#25 5 months ago

I don't have much to add, I just came here to learn some new stuff about rectifiers.

However, I would like to commend you on the photos in the original post. Its always nice to see clear, up-close, well-lit, and focused pics when someone is asking for help/advice, it makes it that much easier to see what is going on. And these photos represent that at the top level.

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