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RFM Right Flipper stuck up


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Hey guys, my newly acquired RFM machine has it's right flipper stuck in the up position. Upon powering the machine on, the flipper is down (as it should be), it's only after the Pinball 2000 PC has finished loading, that the flipper is suddenly stuck in the upright position. Upon further testing, it certainly seems to be the flipper hold cicruit, that's at fault.. But I'm at my wits end as to how to fix this..:unsure

 

I've posted about this over on pinside as well, but I've not made any real progress yet towards a solution yet, aside from replacing two transistors (Q35, and Q36) on my power driver board, but my right flipper is still permanently stuck up. :p

 

Any help here would be fantastic - I don't want to go and spend $400+ on a board and find out that it's a faulty solenoid or something..

 

Please help? My RFM has been outta action since Christmas, and I'm dying a little on the inside...!

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I had this on my tz.

I blow resistor cos I wired up the coil wrong. Lol. Dumb moment.

 

It is most probably the transistor.

That was my issue.

Replaced the transistor and all is good.

 

It was the small resistor not the large one.

Sorry i don't remember the number.

 

You can use a DMM to test them but they are cheap and not to hard to replace so I would start there.

 

 

Sent from my iPhone using Tapatalk

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If the diode across the coil is dead and shorted out, you'll blow a new transistor on the very first test. Check the diode across the coil and replace both diode and the switching transistor if the diode is bad.

 

Michi.

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Bad opto?

 

Do you mean bad solenoid??

I'm not aware there's an optic switch here - or have I mis-interpreted what you mean by opto?

 

To clarify fully, the flipper WAS working when I purchased the machine 2 months ago.. I'd noticed a couple of times the right flipper would get stuck up during gameplay for a second to two, but always went back down. I put this in the 'too hard for now' basket.. Clearly I shouldn't have..

 

We turned the game on, the day before Christmas and the flipper has been permanently stuck up since then.. (Seems to be the hold circuit, not the power circuit, that's firing)

 

Thanks for the help so far, I'll have a look at things tonight and let you all know

 

 

Sent from my iPhone using Aussie Arcade

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Do you mean bad solenoid??

I'm not aware there's an optic switch here - or have I mis-interpreted what you mean by opto?

 

Some flipper buttons use an opto instead of a leaf switch

They look like two little pieces of black lego and something goes in the gap to make the switch circuit

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Tell it to pull its head in and wake up to itself!!

 

Seriously though, you need to determine WHERE the fault lies. Is it something telling the electronics that the flipper should be activated OR is it faulty electronics forcing the coil activation?

 

You need to work that out before replacing parts willy-nilly.

 

Study the circuit carefully and measure the input to the electronics from the flipper switches to ensure they are working correctly first.

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Do you mean bad solenoid??

I'm not aware there's an optic switch here - or have I mis-interpreted what you mean by opto?

 

To clarify fully, the flipper WAS working when I purchased the machine 2 months ago.. I'd noticed a couple of times the right flipper would get stuck up during gameplay for a second to two, but always went back down. I put this in the 'too hard for now' basket.. Clearly I shouldn't have..

 

We turned the game on, the day before Christmas and the flipper has been permanently stuck up since then.. (Seems to be the hold circuit, not the power circuit, that's firing)

 

Thanks for the help so far, I'll have a look at things tonight and let you all know

 

 

Sent from my iPhone using Aussie Arcade

 

Flipper switch opto

Do a switch test to find out

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When I run the inbuilt diagnostics tests, no flipper related errors are detected (just both my inlane return switches apparently don't work..)

 

If I go into solenoid tests, the flipper is still stuck up, but if you force it down a little, you can feel a kick from the 'power' test, but feel nothing from the 'hold' test for the right flipper.

 

At no point do I get an error anywhere in the diagnostics about flippers..

 

 

Sent from my iPhone using Aussie Arcade

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Switch the left bank of flipper buttons and pcb's to the right and visa versa an see if the left flipper now stays up

 

Just tried that, no difference, even with the flipper PCBs swapped over, the issue stays with the right flipper, but good suggestion :) Keep em coming..

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Does the flipper drop to its normal rest state when you open the coin door

 

 

Sent from my iPad using Aussie Arcade

 

Yes, if the coin door is closed, flipper is up. If the coin door is open, flipper Is down.

 

And during boot of the machine too. If the coin door is closed upon boot, the flipper stays down until up until the point where the computer has finished booting, then the flipper flips up.

 

 

Sent from my iPhone using Aussie Arcade

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Yes, if the coin door is closed, flipper is up. If the coin door is open, flipper Is down.

 

And during boot of the machine too. If the coin door is closed upon boot, the flipper stays down until up until the point where the computer has finished booting, then the flipper flips up.

 

 

Sent from my iPhone using Aussie Arcade

mate that sounds reasonable because all coil voltages are disabled while the door is open.
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Yes, if the coin door is closed, flipper is up. If the coin door is open, flipper Is down.

 

And during boot of the machine too. If the coin door is closed upon boot, the flipper stays down until up until the point where the computer has finished booting, then the flipper flips up.

 

 

Sent from my iPhone using Aussie Arcade

These are the (output)circuits we're talking about correct?

 

IMG_1862.thumb.jpg.bce814795f671bf041f3c6af1f437bf6.jpg

 

IMG_1859.thumb.jpg.cde4b5833038da1910c3444fc8bd507a.jpg

 

Oh I have assumed you checked the flipper button switch in switch test to make sure it's not on?

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Yep I had one one Monster Bash

That as soon as you pushed start it would lock on

Then open coin door then drop

Plastic was cracked & just hanging in, it was just enough for it to fall out of alignment of the Opto thus causing the flipper to stick up

 

 

Sent from my iPad using Aussie Arcade

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Agree, sometimes those plastic actuators do warp and cause issues

 

And that will check the associated wiring to the processor, more to the point.

I'm no expert here, but just going on my SS experience and @Homepin I know where your coming from.

Shotguning is not the way (changing transistors). @Michi has a good point in post #4

But there are some other checks even you would agree have some merit.

Shorts down to ground as @Autosteve mentioned in post #5.

An easy test.

If we disconnect

J103 and J112 we isolate that part of the circuit yes?

Pins 1 and 2 on j112 gets switch to ground when flipper is actuated.

Not at the same time that's where the eos switch comes in.

But the point being if you test pins 1and 2 they should not be down to ground.

If one or the other is, your problem is in the playfield wiring.

That should eliminate the playfield or further back.

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Sorry for the slow reply guys - I've struggled to give this issue the time it has needed this week.

However, tonight I had a friend visit tonight who's much more versed in electronics than I (owned a local business for nearly 2 decades :o), which helped greatly.

 

Please have a read over our conclusion here and let me know if you think anything else could be at fault, or if we've simply come to a wrong conclusion.

 

The conclusion we came to was that the coils, wiring, diodes and transistors in the right flipper circuit were all dandy (according to the RFM schematic and the manual page provided by toads in post #18 on page 2). We found that the issue looks like it lies with the 74HCT574 chip (U28) that sends the signals to the transistors/flipper circuitry... :(

 

We compared the powered up voltages of the left and right flippers to each other at the flipper solenoids. The (faulty) right flipper had next to 0 volts on the orange/green wire connector, where as all other connectors on both flippers had ~68-70volts on them each. We confirmed this at the J112 board jumper also.

 

Tracing that back through the circuit diagram (PM'd to be my Fire_Power - oh man that helped immensely- Thanks!), led us to chip U28, which is a 74HCT574 chip.

 

Reading the schematics of that chip online and looking through the layout of the circuit schematic, we determined:

Pin 3 is the input for Pin 18, which runs to the Right flipper hold circuit.

Pin 5 is the input for Pin 16, which runs to the Left flipper hold circuit.

With the machine on, in attract mode and with the coin door shut and no flipper buttons depressed, we found the input voltages of pin 3 and pin 5 were ~5v, the outputs of pin 16 (left flipper), was 0v, however the output of Pin 18 was 5v (right flipper).

 

Which leads us to believe that this 74HCT574 chip is the fault, because why the heck would it randomly supply 5v to one flipper and not the other, when the flipper is not engaged..

 

Does all that make sense to you guys?

Seems that my issue would be resolved by replacing this 74HCT574 chip?

 

Thanks so much for all the help thus far everyone, you've all been amazing!:)

 

 

These are the (output)circuits we're talking about correct?

[ATTACH=CONFIG]104269[/ATTACH]

[ATTACH=CONFIG]104270[/ATTACH]

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That sounds like a good analysis to me. I've been following this thread all along and been scratching my head, but haven't said any more because I was fresh out of ideas.

 

Looks like replacing that chip would be the next thing to try. It drives the transistors that switch the flipper circuit. If you are seeing 5V on the right flipper output, it's no surprise that the I/O driver board obligingly powers the coil…

 

Good detective work!

 

Michi.

Edited by Michi
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Sounds like you're on the track of it, but before replacing the IC I'ld break the circuit before it goes into the 470 ohm series resistor R139 and do your tests again. This is pretty quick to verify the IC is the problem and easier than lifting the IC as a first test.
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Sounds like you're on the track of it, but before replacing the IC I'ld break the circuit before it goes into the 470 ohm series resistor R139 and do your tests again. This is pretty quick to verify the IC is the problem and easier than lifting the IC as a first test.

 

I've unplugged the right flipper hold cable from the solenoid and retested with the same results. Is that an effective test? Or did you mean me to break the circuit (desolder something?) between the resistor and the 74HCT574 chip and retest?

 

On that topic, if I left the connector on the hold circuit of the right flipper solenoid unplugged at the solenoid, and powered up the machine to run some diagnostic tests, would this cause any harm? Even if I fired the flipper a bundle of times (Eg, had a test game or two)?

 

I understand my right flipper is only going to flip around like mad and potentially burn out my solenoid if I hold the right flipper button down, but assuming I don't do that, nothing should go wrong should it?

 

Thoughts?

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