My guess would be a cold solder joint that makes contact as the games warms up, but the odd pulsing behavior of U18 is not something I've seen before. Did you try replacing U18?
(Topic ID: 201744)
You're currently viewing posts by Pinsider lyonsden.
Click here to go back to viewing the entire thread.
1 week later
Quoted from mjalexan:Replaced C4 because it’s easy and I had one.
From power on, attract mode, probing TP2 and TP5, starts off at 4.7-4.75V. As voltage increases over 4-5 minutes, more lights come on. All lights come on around 5-5.02V. Voltage stops raising around 5.03V
I’ve reflowed all relevant connections, I think: J101-1,2, BR2 all, C5 both, C9 both, LM323 all,C4 both, U8 and U19. I’m stumped at this point, ready to buy a new C5 and LM323. Any other suggestions lyonsden ?
Hmm. I haven't seen/heard of that problem before, but I would suspect the 5V voltage regulator. While I am not a fan (in general) of replacing parts without know which one really needs to be replaced, you can try to replace the 5V voltage regulator with this one: http://www.ezsbc.com/index.php/featured-products-list-home-page/psu5.html#.Vyo9i2Za4yM
It is something that I put in all my WPC games along with this one for the 12V voltage regulator: http://www.ezsbc.com/index.php/featured-products-list-home-page/psu3-12.html#.Vyo-L2Za4yM
One thing that I am surprised by is that you aren't seeing resets by the MPU with the low 5V voltage. The MPU is infamous for reseting when the 5V voltage drops. You may want to go through this guide on the 5V WPC resets: http://pinwiki.com/wiki/index.php?title=Williams_WPC#Game_resets to check all the components in the 5V circuit (e.g., do you have all the screws securing the power driver board that also act as ground for the board?)
Quoted from mjalexan:Hear ya on C4, it was handy and it seemed a possibles source. The C5 cap sounded difficult to replace from a what I’ve read so I was saving it for last. Driver board is secured with all 9 screws. Wondering if the lights are just the start of the 5V issue, the U9 and U18 are furthest from C4. If you aren’t looking at the lights it would be easy to miss until restarts began. I can do any diagnostics/pics/video if you have any ideas. There is a local guy I’m sure could resolve this, trying to avoid basement removal and gain some knowledge.
I think there are two general things that could be causing 5V to measure low. The input voltage to the 5V voltage regulator or something downstream that is drawing too much current. Have you measured the voltage coming into the 5V voltage regulator?
I was thinking about this some more and think that you are looking at two different things. The 5V line does not necessarily affect the controlled lamps (though the 5V circuit may be powering the board components that control those lights). Look at this: http://pinwiki.com/wiki/index.php?title=Williams_WPC#Controlled_Lamp_Operational_Description
Key to note is that power to the controlled lamps is coming from the 18V circuit (pulsed to bring the effective voltage/current down).
Check the 18V circuit:
"Lack of 18V lamp matrix power. If LED6 is not lit, or TP8 shows other than 18V, "buzz" F114 for continuity with your DMM. If F114 is blown, test BR1 using the method specified here."
You may have a bad connection with F114. Remove the fuse, check the contacts for corrosion, look for cold solder joints on the fuse holders, etc.
1 week later
Promoted items from Pinside Marketplace and Pinside Shops!
Westminster, MA
You're currently viewing posts by Pinsider lyonsden.
Click here to go back to viewing the entire thread.
Reply
Wanna join the discussion? Please sign in to reply to this topic.
Hey there! Welcome to Pinside!
Donate to PinsideGreat to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
