(Topic ID: 325696)

TZ detecting powerball while not in play / bridge rectifier testing? [solved]

By dEviant

1 year ago


Topic Heartbeat

Topic Stats

  • 26 posts
  • 9 Pinsiders participating
  • Latest reply 1 year ago by Coyote
  • Topic is favorited by 1 Pinsider

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#1 1 year ago

So my TZ is giving me a royal headache. Again. Symptoms are that the game logic sometimes thinks that the powerball is in play while it is not, but this does not happen all the time. Running a switch test does not seem to show anything obvious. I did notice a few times (yesterday) that the gumball upkicker was erratically firing a few times. Forum wisdom suggested that this may be a problem with the 12v unregulated circuit. So I started looking at the power driver board. Fuses are fine. TP voltages are fine - albeit a bit high (14.9v where 12v is expected, at least there is 4.95v where 5v is expected).

A test of the bridge rectifiers has left me dumbfounded: Following the bridge rectifier test on PinWiki [here: https://www.pinwiki.com/wiki/index.php?title=General#Testing_a_Bridge_Rectifier] if in step 2 I place the black lead on the "oddball" leg of BR5 (KBPC3502W) and use the red lead to test the two adjacent ones, one reads the expected .5 v, and the other... around 1.5v. This persists when placing the red lead on the opposite leg and using the black lead to test the two adjacent ones (step 5/6 on pinwiki). This would suggest that BR5 is broken. Testing BR3/4 has the same results.

I then repeated this test on a few replacement (KBPC3502W) bridge rectifiers that I still had from a previous board repair. All 3 that I have show the same test results. I am now left trying to understand what is going on here, are BR3/4/5 broken and do they need replacing? Are the spare ones I have also broken? The latter seems very unlikely to me which is why I thought I'd ask for some advice here.

EDIT: for solution, see post #14 (bridge rectifier testing), and post #18 (powerball detection)

#2 1 year ago

whoa, you're treating a broken thumb with quadruple bypass surgery, here.

first of all, these are likely two unique and unrelated problems. start w the basic remedies. and if you discover through those, that they're deeper than than just the basics, then start doing serious PCB component investigating.

1) the game thinks the powerball is in play when it's not: this is likely a failure of one or both of the eddy sensor boards (one by the trough eject, other in the center of the subway). Those are what tell the machine if the ball in play is steel, or not. might need to adjust the pot adustment, or replace them altogether.

2) the random firing of the gumball popper: likely an issue with the opto in the popper VUK. game thinks a ball is in there when it's not. could be a loose solder joint on the optos, failure of the opto emitter/receiver themselves, or it's simply dirty. try wiping the lenses of both the emitter and receiver w a dry q-tip. see if the problem goes away. if that doesn't work, then try resoldering the wires w fresh solder. If that fails, try replacing both opto boards w new ones. there's a very good chance you won't have to do much beyond those things.

#3 1 year ago
Quoted from bigehrl:

2) the random firing of the gumball popper: likely an issue with the opto in the popper VUK. game thinks a ball is in there when it's not. could be a loose solder joint on the optos, failure of the opto emitter/receiver themselves, or it's simply dirty.

or simply even a broken wire to one of the transmitter or receiver opto boards.

#4 1 year ago
Quoted from bigehrl:

whoa, you're treating a broken thumb with quadruple bypass surgery, here.

Yeah I realized that while I tried my best to clearly and concisely get a problem across, I mixed up two separate issues which was likely to confuse folks. My apologies for that.

As for the 'powerball in play' after more extensive playtesting I realized that this happens when the pinball is ejected from the trough, but as soon as it hits the slot machine, the game realizes that its not the powerball and corrects itself. That told me that the eddy sensor in the slotmachine works, but the one in the trough had an issue, which makes sense because I recently fixed the "intermittent powerball detection in the trough" issue by (finally, this has haunted me for very long) getting rid of the flaky connectors and soldering wires directly on to the pins. After some playtesting I thought I had aligned the sensor properly but apparently that was not the case. I was then able to reproduce the issue in test mode, modified the alignment, and the issue went away (for now...).

Then the 12v issue. What I left out is that I have reason to believe that the 12v unregulated circuit is, well, flaky to say the least. There are two symptoms. One is that a colordmd control board got fried. With the help of their support it was determined that what likely happened is that a transient spike came through J116 on the power driver board, where the colordmd gets its 5v/12v from. I have also seen some random resets earlier in the day, while idling in the test menu. This hints at the 5v circuit being an issue. Reading the forum, I found out that other symptoms of a potential issue with the 12v circuit could be optos acting flaky - such as the gumball popper firing randomly during gameplay. And this is exactly what I noticed right before the colordmd went dark. While the color dmd control board is shipped out for repairs, I wanted to verify that there is no issue with the 5v/12v circuit so that I'm not going to fry the repaired or replaced control board again. The power driver board did have bridge rectifier / capacitor replacement repairs done by me in the past, but at the time I did not replace all of them. Plus I read on the forum from a reputable board repair tech person that bridge rectifiers can go bad over time. This brought me to testing the bridge rectifiers, noticing that neither the in-circuit nor out of circuit tests make any sense, and thought to post my findings here to try to demystify these observations.

Maybe it would have saved a lot of confusion if I had properly introduced you all to my TZ. It is Very Temperamental. You fix one thing and two other issues show up. I swear just looking at it wrong causes it to act up in the weirdest ways.

For now I replaced the power driver board with a spare, new/unused rottendog one, while figuring out if there is anything wrong with the one that took out the colordmd control board.

#5 1 year ago

Were you doing any kind of repair while the game was on before any of your issues started?

#6 1 year ago
Quoted from PinballManiac40:

Were you doing any kind of repair while the game was on before any of your issues started?

No, I turn the machine off when I work on it. Except if I am replacing very easy to reach lightbulbs.

#7 1 year ago
Quoted from dEviant:

No, I turn the machine off when I work on it. Except if I am replacing very easy to reach lightbulbs.

Very good to hear. Just trying to understand what your issue with the 12V unregulated could have been caused by. It is normal for that voltage to be just under 15V.

#8 1 year ago

I did replace a column driver transistor (Q95) because all lights in that column were out, and I could visually see that one of the 3 legs had snapped. I used a soldering station / desoldering gun to do that, and cleaned up the area. That repair worked out just fine, but following a power cycle the ColorDMD did not come on and none of the LEDs on the control board came on. I checked the 5V/12V test pins as well as the voltage at J116 and the connector on the colordmd control board, which were 4.95 and 14.93 respectively. I can't tell if the 14v seems is too high or not. I hope that this clarifies the pathway that led me to testing the bridge rectifiers a bit better

#9 1 year ago

There is a regulated 12V also on the driver board. That one is normally 11.75 to 12.25V.

#10 1 year ago

Do you have any other mods attached to J116-J118 other than the ColorDMD? We already know that lighted LED strips or LED lighted buttons can cause that 12V unregulated fuse to blow in the top left corner on the original power driver board.

#11 1 year ago
Quoted from PinballManiac40:

Do you have any other mods attached to J116-J118 other than the ColorDMD? We already know that lighted LED strips or LED lighted buttons can cause that 12V unregulated fuse to blow in the top left corner on the original power driver board.

No mods that are attached to J116-J118. I do have a car, robby the robot, rocket ship, gumball lights, camera, lamp post mod - but they are all attached to the respective insert lights. And a TV mod that is alligator clipped to a 5v point under the playfield. I have had this configuration for as long as I had the ColorDMD installed (no new mods since 2017 ish) and never had any issues.

#12 1 year ago

I can probably think about wiring the TV mod into 5v power elsewhere, but I guess the prime candidate for that would be J116-J118. Or install a 5v power supply in the service outlet inside the machine.

#13 1 year ago

Less on J116-J118, the better. That was why I was about mods.

Nothing came loose by chance and shorted something before you replaced Q95?

#14 1 year ago
Quoted from PinballManiac40:

Less on J116-J118, the better. That was why I was about mods.
Nothing came loose by chance and shorted something before you replaced Q95?

Not that I know of. I guess this will be a good excuse for me to get a lot more comfortable with board repairs and testing.

I think I figured out why I was having such weird readings with the bridge rectifiers both in-circuit and when testing just the components. The PinWiki site, as well as the linked video, suggest that the 'oddball pin on the bridge rectifier is the DC +'. However, the KBPC3502W pinout is different- the 'oddball' pin is one of the 2 AC pins, and the adjacent pin that is both horizontally and vertically offset from it, is the DC +. Using that updated bit of information to test the components that I have, now the readings are what you would expect, and indicative of working components. Now I can get back to testing the bridge rectifiers on the power driver board, and continue the debugging/troubleshooting process from there

#15 1 year ago

For your two issues, definately not a bridge rectifier. I agree with this below. You have certain common problems as any other TZ. They are even identified in Pinwiki.

Quoted from bigehrl:

1) the game thinks the powerball is in play when it's not: this is likely a failure of one or both of the eddy sensor boards (one by the trough eject, other in the center of the subway). Those are what tell the machine if the ball in play is steel, or not. might need to adjust the pot adustment, or replace them altogether.

2) the random firing of the gumball popper: likely an issue with the opto in the popper VUK. game thinks a ball is in there when it's not. could be a loose solder joint on the optos, failure of the opto emitter/receiver themselves, or it's simply dirty. try wiping the lenses of both the emitter and receiver w a dry q-tip. see if the problem goes away. if that doesn't work, then try resoldering the wires w fresh solder. If that fails, try replacing both opto boards w new ones. there's a very good chance you won't have to do much beyond those things.

#16 1 year ago

At the ball trough there is a small coil on a PCB that senses the next ball to be kicked out.

The adjustment on this board is frequently bad, and the ball actually touches and destroys the coil on this board.

Here is some advice:

https://pinwiki.com/wiki/index.php/Twilight_Zone_Eddy_Boards

I've had to replace these little sensor coils before. Looks like there is a seller here:

https://www.tanglestech.com/tpp-1038

I didn't find the sensor coil anymore at Marco or Pinball Life. At least the Eddy sensor boards are readily available.

#17 1 year ago

The gumball entry transmitter or receiver probably has a cracked solder joint / broken leg making intermittent contact. It's a high vibration area and common fault for the opto pair to have an issue.

Rob

1 week later
#18 1 year ago

I thought I had posted the issue/solution but apparently I did not. PinballManiac40 PinRetail Rob_G thanks for your suggestions, they were spot on! The issue was a misaligned sensor pcb, in combination with a flaky connector (on both sides) between the eddy main board and breakout pcb (the small one with the coil). I tried taking out the pins, bending them back into shape, and reinserting them into the connector housing, but that turned out to be a temporary fix. I thought about repinning the connector but decided against it, and instead cut off the connectors on both ends and soldered the wires directly onto the pins on the pcb's. I have not had a single powerball issue since.

Quoted from PinRetail:

I've had to replace these little sensor coils before. Looks like there is a seller here:
https://www.tanglestech.com/tpp-1038
I didn't find the sensor coil anymore at Marco or Pinball Life. At least the Eddy sensor boards are readily available.

I've had the sensor coil snap off its legs before. I had ordered a replacement eddy+sensor board, but also tried to repair the sensor coil by resoldering it onto the pcb (I was unable to find sensor coil replacement parts at the time). I did not expect that to work out but it did. Nevertheless, I will be ordering a replacement sensor coil. Thank you for posting that!

Quoted from Rob_G:

The gumball entry transmitter or receiver probably has a cracked solder joint / broken leg making intermittent contact. It's a high vibration area and common fault for the opto pair to have an issue.

I think I've had this issue before, but I can't remember whether that was on the TZ that I currently own, or the one I had before that. Selling off that machine was one of the two major regrets in life, so I just had to get it back. Now, given all the consistent issues that I've been having ("fix one issue, two more will appear") I now remember why I sold it in the first place All joking aside, I have not heard any spurious gumball popper firing in a while now. If/when it comes back, or when I do the playfield swap (whichever comes first), checking the legs / reflowing the solder joints will be the first thing I will do. Thanks again!

#19 1 year ago
Quoted from dEviant:

I thought about repinning the connector but decided against it, and instead cut off the connectors on both ends and soldered the wires directly onto the pins on the pcb's. I have not had a single powerball issue since.

This has actually been *the* fix for these two boards for ... hell, over a decade now. Glad you got it, though!

#20 1 year ago
Quoted from Coyote:

This has actually been *the* fix for these two boards for ... hell, over a decade now. Glad you got it, though!

I have absolutely no problem admitting that I can be a bit of a dense, stubborn, and slow learner

#21 1 year ago
Quoted from dEviant:

I have absolutely no problem admitting that I can be a bit of a dense, stubborn, and slow learner

Nah, not poking fun, I'm not sure if/why it wasn't brought up earlier, actually.

#22 1 year ago

Same issue w my TZ

Will use recommend solution first

#23 1 year ago

When you adjust the trough proximity sensor, make sure it's close, but not touching the balls.

Rob

1 month later
#24 1 year ago

I have newer anarchy eddy board in my TZ. Ive been getting proximity error sometimes. It is my understanding that light should be off with steel ball and on when it doesn't detect steel (ie powerball is next to sensor) is that correct?

Sounds like I should just solder wires to pins and that should be my fix?

#25 1 year ago

Funny you bring up bridge rectifiers going bad. When I got my TZ in 1999 I had to replace both rectifiers on the power driver board. Well as if 2020 didn’t suck already was getting random resets. Well I told myself I replaced those guys when I got the machine they should be fine since my game is only on a couple times a month. Well wrong I was both were flakey after 21 years of home use. TZ is pretty power hungry game so I can see why it’s a bit more sensitive to old bridge rectifiers.

Also anyone who owns a tz for a while will have that power ball trough adjustment more than once. Part of owning a TZ. The trick I found was to secure the sensor with UV epoxy so it doesn’t move. Since I’ve done that I have seldom had an issue with the sensor.

Great pin! love mine was the pin I bought off eBay from a seller in France. Mine is an early production with green locks,white clock and extra post in pop bumpers. Unfortunately no 3rd magnet. Game is fantastic and I’ll keep playing for some time. Always a rush to get lost in the zone…..

#26 1 year ago
Quoted from drewbo81:

It is my understanding that light should be off with steel ball and on when it doesn't detect steel (ie powerball is next to sensor) is that correct

Reverse this.
LED on when detecting steel ball (and closing the switch on the matrix). Off when no steel.

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