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(Topic ID: 265218)

WhiteWater - Audio Board - Fart and Fire


By MrCleanHead

6 months ago



Topic Stats

  • 10 posts
  • 7 Pinsiders participating
  • Latest reply 6 months ago by MrCleanHead
  • Topic is favorited by 3 Pinsiders

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#1 6 months ago

Hi Everyone,

Im new to Pinside and first time posting. Since Im stuck at home I figured I would go through all my pins and get up 100% to enjoy them again.

I have a Whiter Water pin that I have owned for about 23 years now and has been sitting for about 3 years. No mods to the machine and the only repairs that I have done were the replacing the bridge rectifiers and capacitors on the power driver board for the reset problem, this was done years ago. So last week it was Whiter Waters turn to get up and running and install NVRAM. I visually checked under the play field and the boards to make sure nothing looked out of place. Turned the game on and the DMD came on, I had the back glass off but the light door closed, seen a flash, then the game made a fart sound, I opened the back box up and then the Audio Board started to catch fire. Turned it off and unplugged it. This all happened in seconds.

Seems that C27, C29, C26 and C28 burned up. Maybe others are bad, but this is what I see (attached pics)

I checked all fuses, they checked good. Visually checked the wiring and plugs. Installed the NVRAM since I was pulling boards

This is a new issue for me since I have had only little problems over the years that I can fix.

So...Where to start? Im not sure what to check, what I should have unplugged to check, etc... Im somewhat afraid to turn it on :-\

Any help would be great, and thanks in advance.

Rob

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#2 6 months ago

The tantalum capacitors tend to explode after an X number of years.

Check the tantalum capacitors C26, C28, C46, C47. Capacitor C27 and C29 are likely hit by the exploding C26 but replace them anyway.
Check traces on both sides of the circuit board.

C46 and C47 are next to the heatsink of the LM1875.

All above capacitors have (+) and (-) !
Replace with 1uF 35 Volt capacitors (tantalum/electrolytic)

#3 6 months ago

Thanks for the reply. I will replace those capacitors. Since Im in here doing board work is there anything else I should replace just for preventative maintenance? Does any one sell get well kits for these pins like they do for arcade monitors?

#4 6 months ago

Like zaza noted, those tantalum caps simply give up the ghost after a period of time and quite spectacularly.

You can replace the 47uf caps on the board to improve audio just a smidge, but then again, it is a WhiteWater, a game with generally not great audio in the first place.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#5 6 months ago

Had a tantalum cap do the same thing on my Dr. Who that had been sitting for a few years.
https://pinside.com/pinball/forum/topic/dr-who-audio-board-cap-exploded

#7 6 months ago

Yes, this has happened on several of my games. I replaced the tantalum caps with more readily available electrolytic caps. Seems to work fine... Anybody know of a reason not to use electrolytic?

#8 6 months ago
Quoted from kevmad:

Anybody know of a reason not to use electrolytic?

Nope. No reason. Tantalums were originally used becasue , "tantalum oxide capacitors have a much higher capacitance value for their size. They are more expensive than aluminum oxide, but they are more reliable, more stable, and they operate better at certain frequencies."
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#9 6 months ago

Tantalums were usually used back then due to low ESR and tighter tolerance in these circuits. Often used in audio circuits due to the tight tolerance.

Tantalums do not go bad with age...period. Age has nothing to do with these.
The thing that does kill tantalums is repeated over-voltages or reverse voltages over the years. An electrolytic tends to have a higher voltage rating and just 'skates' over the over-voltages.

The downside to tantalums is their failure mode. As you have witnessed, they don't die gracefully.
The upside is their lifespan (if they are repeatedly hit with spikes) and their tolerance.
In a proper circuit - they last forever. We have worked on lots of 1970s and 1980s military equipment where tantalum cap failures are unheard of.

The downside to electrolytics is their short life span (even if just sitting on shelf), huge tolerance (as much as 80% tolerance) and high series resistance for standard parts.
The upside is their low cost and high capacitance values.

Improvements to ceramic and electroltyic capacitors have been tremendous in the past 20 years. Electrolytics are now available in very low ESR and have longer life spans but still suck in tolerance. Tantalums have pretty much stood still and are losing ground to high capacitance ceramics.

#10 6 months ago

Update: I replaced C26, C27, C28, C29, C46 and C47 as pointed out and the game is up and running as normal. Thanks to all that helped out. Im glad I found this site, spend a few hours getting lost in all the content. Sure is way different looking for info than it was in the late 90's. I used to know the operators tech routes and meet them at the bar for info (So I guess I you guys a beer!). Good times.

Thanks again! Now to tare it down and clean it since Im stuck at home

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