(Topic ID: 295337)

WPC gi not dimming all the way.. spanker

By Hawk007

2 years ago


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  • 20 posts
  • 5 Pinsiders participating
  • Latest reply 2 years ago by pins4u
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#1 2 years ago

Hello Got my BSD getting restored and found org /org wht string of GI not dimming. Checked everything to find c2 puked and damaged traces and u1 74ls374 bad.
Repaired traces and new u1......success string dimms BUT heres the catch....it does not go out all the way. Has all stages of dimming now but will not go out completely when it should....

Anyone else ever have this? tested many components and all are good..triacs,resistors etc. Thoughts?

#2 2 years ago

anyone? Evening bump cheers

#3 2 years ago

no one? any ideas at all? Thanks for looking. cheers

#4 2 years ago

So if you go in settings, test , general illumination , change the test to "upper backbox , WHT-ORN" (on my Fish Tales that's how it is) then at that point you can adjust the illumination from 1 to 8 and this works. If you go to the next test , "upper playfield , WHT-YEL" , the string from the upper backbox remains lit? When testing 1 to 8 illumination , you don't turn off the string until you go to the next test. Illumination 1 does not turn off the string and you can't test illumination 0 in the test mode.

#5 2 years ago

Thanks for your response ...And yup. I agree. BUT the org org wht string on mine stays on a little when the driver board enables GI. All other strings perform perfectly and dim to dark as they should and go out as per above with next test etc

An example is when u go to all dim test and set to 1 that org org wht string is brighter.

When the game is off for a long time it works perfectly for about 4 pulses of the GI..if u know Drac it dims the GI and alternates with other strings going on and off from out to on and said bad string does not go all the way out after about 4 pulses.

Seems like a failing cap or a trace but the circuit is so simple and everything else is fine. signals to u1 are great.....hmmmm All components test good.

#6 2 years ago

Anyone else have any ideas? A thought..... where would the org org wht string get 2.5 negative dc volts across the string? Really weird. lol stay cool and thx for any input.

#7 2 years ago

Try to test with a single bulb.
Unplug J119/120/121 and use 1 lamp only to test the 5 circuits.
This way you can exclude the playfield as a possible cause.

#8 2 years ago

Thanks zaza. Great idea. But i forgot to mention it does this out of the game with a test fixture as well.. Which sucks as its now not wiring related. tried another driver board in it and it works flawlessly.
Really weird....

#9 2 years ago
Quoted from Hawk007:

c2 puked and damaged traces and u1 74ls374

The data lines are very close to C2, be sure the circuit board is clean and traces have 0 ohm resistance around C2 and U1

#10 2 years ago

Another great idea thanks zaza! K had a few mins to recheck and make sure. all data traces from the ribbon header to U1 have no resistance. I always check after repair but great idea to check again.

Interestingly enough there was initially a bad via by u1 supplying signal to the bad string!!! i had to jumper output of pin 19 to the via to make it have 0 resistance to where it goes too but still no joy.
Had to jumper the flipper relay enable line right away as well as there was a failing trace from cap corrosion causing the relay to freak out.

These were all initial repairs. So maybe i need to solder the jumper from pin 19 farther back from the via even tho it tests 0 resistance it may break down under load yes?

#11 2 years ago
Quoted from Hawk007:

it may break down under load yes?

Not really, this is a signal line and there is virtually no current flowing here.

As you have already fixed several traces around here I suspect that will be your problem.

As Zaza says, trace out EVERY connection around here, the traces are stupidly fine and I'm amazed these boards have lasted as long as they have.

#12 2 years ago

Another idea,
Has Q10 been replaced in the past ? Is it the correct Triac ? resistor R8 in spec ?

#13 2 years ago

Picture of the board would be nice to see whether the leakage from C2 damaged any traces.

#14 2 years ago

This is very easy to diagnose on your board. Thing is, even if all traces read 0 ohms between where they go, doesn't rule out that this particular signal isn't affected by the corrosion between that signal and another close by. Continuity only tells you there is a direct connection between those 2 points, but it won't show you that the same wire might be reading a weird resistance between another pin that isn't related at all and is affecting the signal.

Is U1 on a socket now that it has been replaced ? I hope so, rule of thumb if you replace an IC , you should put a socket instead. If it's socketed , pull out the chip , bend pin 19 and put the IC back in. Is the string still dimly light ? If so (very probable) it means that R8 is sensing a voltage on it's pin and that is what is driving the lights. If this is the case , it means that corrosion is still present on that trace and you now have to find out where on the board that trace is affected. Since pin 19 (signal) and pin 20 (VCC) are so close, it sounds very likely that you still have corrosion affecting pin 19 and creating a resistance to pin 20 , which is in turn sending voltage to R8 and lighting up the string. If you measure resistance between pin 20 and pins 2,5,6,9,12,15,16 and 19 they should all be very similar, I'm almost certain you'll measure a resistance between that differs from the rest between pins 20 and 19.

The overall troubleshooting sequence should be this : Under similar conditions , compare the voltage (DC volts , black probe on ground) and resistors R8,R11,R14,R17 and R20. They are supposed to have a voltage very close to each other. If this is the case, then the trouble would have to be on the side towards the transistor/triac and the bulbs. If the voltage of the problematic line differs from the other , then you have to look at the other side of the circuit , which is the IC directly. If it's on the IC side , then you have to compare the voltage of each input D0 to D7 to check if they are similar or not. If they are (they should) then you've identified the problem between the output of the IC and resistor R8.

You said that the lights have all their levels of dimming , which means the side with the transistor and the triac are "functionning". That still doesn't rule out if corrosion is in that part of the circuit.

Are you confident enough in your work to actually show us a picture of the U1 area properly cleaned and repair after the corrosion ?

On the picture , compare what's marked in orange first, then the side in red of the IC , and last the green zone that drives the triac.

pin6.pngpin6.png

#15 2 years ago

Thank you for your detailed post and information @Roamin. And everyone! U all rock. I am very confident in my work soldering etc and always use machine pin military grade strips for IC's. However my camera sucks along with picture taking lol. Closeups anyways. :-/

All pins have continuity but means nothing as its hidden corrosion somewhere causing this for sure......

That said I still had the board on my lap so I cleaned the area again with a 10x eye loupe on and found the tiniest piece of flux/cap goop or ? hiding up high on the strip legs looking like part of the socket plastic !! Sneaky stuff lol I got rid of it, then iso wiped the area again and its working properly now. thank you again Roamin and everyone.

Onto fix the 24 opto board. Anyone know what the real value of R1 is on a working 24 opto board? Mine had a 2.6kohm installed but schematic calls for a 1kohm? Thoughts? I will post this in another thread as well. Thanks again 1 step closer to a less haunted Drac.

#16 2 years ago

Thanks again .......This was so stupid.. 1 min it tests fine the next it was bad......true spankers are like that Even in game it would be fine then not, test fine and not.... Appealing to you all helped for sure.

have a great weekend all

#17 2 years ago

"Onto fix the 24 opto board. Anyone know what the real value of R1 is on a working 24 opto board? Mine had a 2.6kohm installed but schematic calls for a 1kohm?"

My schematic shows R1 as 1K2 however, it is in a fairly critical position so I would probably think it was fine tuned over the run of the game. This is very UNLIKELY to be you problem however.

With this board it is almost always a leaking 100uf cap causing track problems OR a broken leg on L1 (you can reattach a broken leg by scraping back the hard epoxy coating).

After that it's very likely a dud MC3373 - unobtainium.

Most people just opt to fit a replacement board designed with a different method of operation and never have long opto problems again. $90 and your problems with this circuit are gone.

When I had a BSD I fitted this board and I really liked the extra green LED that you can see through the front door which allows you to tweak the opto brackets and get everything ship shape - too easy!

https://www.pinballlife.com/24-opto-replacement-board-a-15646.html

24"opto (resized).png24"opto (resized).png
#18 2 years ago

Thanks man. Yea the 100uf cap was puked along with the L1 missing, i replaced them both and i added the extra green light thing .

Every 12 volt cap on this game was puked when i got it.Yikes....

The board sometimes starts to work after being on for a long while [why i suspected incorrect r1 resistor]but when not working the signal never changes on the mc3373 when u break the beam,so i fear you are right and its time to pick up the anypin board. Had that on my radar already was just trying to get this running in the meantime. Thanks again pinball friends for your time and expertise Cheers dudes. Stay cool and healthy my friends

#19 2 years ago

apparently u can find mc3373's in old remote controls?? I know where a large pile is hmmmmmm lol

#20 2 years ago
Quoted from Hawk007:

apparently u can find mc3373's in old remote controls?? I know where a large pile is hmmmmmm lol

Probably, but they would have to be VERY old remotes, like 30 years old. Newer remotes almost all use either a COB (a black chip blob on the board) or a surface mount device, most likely a microprocessor of some sort.

The next problem to trust a 30 year old chip that has been in a device that was dropped every day of its life LOL.

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