(Topic ID: 234665)

WPC-S High Power Solenoid Weak issue

By robertmee

5 years ago

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Latest reply 10 months ago by brooklynsystems
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Scratching my head over this one and running out of things to check/test/repair.

Globally, the HP solenoids on a BSD appear weak. The shooter lane barely gets the ball into the upper PF. The Pops seem a bit weak although still bounce the ball around.

What I've done/checked:

BR3 was replaced
C8 100uf cap was replaced
All traces/pads verified with good continuity
TP measures 70VDC unloaded. No AC Ripple on DC signal.
Shooter coil (the one I'm using for tests) measures 70VDC unloaded to ground, 50VDC when firing
Headers J101, 102 and 103 replaced for incoming AC
Plugs at transformer reseated and inspected
Connectors for Grounds on Aux Board for Solenoids reseated
J107 power to coils reseated (Have not replaced this header, however)
Good Screws to Aux Board to Backboard for grounding
Strength seems no different whether coming from transistor on board or if I ground the coil lug directly (tested using ground jumper from cabinet directly to coil)
Diode for this coil on Aux board tests fine

In that there is no difference in strength from a direct ground to board ground, would tell me that it's a power side problem, agree?

So, turns out there was an issue with J107. Swapped connectors J106 with J107, and strength was returned. Will reflow or replace J107.

I know this is 4 years later, but I was having a similar problem with a WPC driver board recently (working on Fish Tales- same power driver board: A-12697-1). Weak solenoids. Fuse F112 (solenoids secondary) had blown once but didn't seem to blow again (later I find a broken trace that explains this...) I recapped the driver board with a kit from Marco - also found a bad Bridge Rectifier - BR3 - had 1 shorted diode, and lastly a trace was burned up on the top of the driver board from BR3 to J104. I used a piece of wire to bridge the trace on top of the board (in retrospect this didn't work).

However when I put it back in the machine, I still had the same symptom- weak solenoids. Hmm.

So it turns out that the through hole traces by the bridge rectifiers are notorious for breaking. When I replaced BR3, I carefully removed the old BR with a Hakko FR-301 (vacuum desoldering tool), and didn't see any solder pads/traces or through hole traces coming out when I was removing it, but I think just removal is enough to break the through hole trace without even knowing it. My solution (thanks, Jeff) is to run jumper wires from J104 / J105 pins 1 & 2 to BR3 A/C poles on the back of the board. J104/J105 are the fused AC coming from the transformer through J102.

Please note that the pinout (for J104/J105) in the BSD (or in my case Fish Tales) Manual is incorrect. The manual says pin 5 is on the left and pin 1 is on the right when looking at the board from the top. But I'm looking at the board and the pins are in the opposite order- pin 1 is on the left and pin 5 is on the right. (pictures included)

This brought everything back to normal! Hope this can help someone who needs it. This problem took me a while to figure out...

Screen Shot 2023-06-09 at 1.34.43 PM (resized).pngScreen Shot 2023-06-09 at 1.36.56 PM (resized).pngWPC89 BR3 jumper wires (resized).jpg

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