My apologies if this has been discussed before, I attempted to search but came up short...

I am working on a Taxi that I thought had a power issue, hoping it was a fuse but now I am not so sure...

The game powers on fine, and coins up. Launches a ball. Whats not working is:

Jet Bumpers
Lola 3 bank drop targets
Left and Right kickers
Left and Right flippers

I was really hoping there was a bad fuse somewhere, but I metered out all of the fuses in the backbox and all is well...

My apologies if I sound new to pinball repair (I am) but I have been working on arcade games for a few years.

I know how to use a multimeter so I tried doing some basic checks but I'm quickly learning that working in pinball machines id much different then arcade games lol

Any guidance you all can provide, I would be very grateful!

Thanks all!

Going through the manual, I have determined that they all (except Lola) run off of the same connector from the CPU... So thats a start.... What should the voltages be at the connector and where would be a good place to ground to in order to check the voltages?

Is there possibly a fuse hidden somewhere that I am missing?

Thank you for the advice... Looks like I'll be running switch tests and checking continuity this evening... I'll report back my findings here.

Ok, at start up, pressed advance and it tells me to check switches 17, 19, and 21 (left, right, and lower bumpers) that would make sense as everything else would be down the line...

During the solenoid test nothing happens when it goes past the bumpers, kickers, etc.

One thing I noticed is that the diagnostic LED on the CPU flashes continuously... like no pauses to count the flashes...

Feeling a little over my head as all the connections seem good. What would the pros suggest I take for the next step?

Videos of the test cycles posting shortly...

Here are the test vids.... Sorry for the crappy cell phone vids.

Test 1 - solenoid test

Test 2 - switch test

Not sure if it makes a difference but the 6 transistors on the CPU are measuring .585 to .600 from base to emitter consistently

Ok, thank you for the direction... I am still learning all these different tests... I'll be running that test next.

Lots of good info here so far... Thank you!

Ran the switch edge test... kicker and flipper button switches are working. Pop bumpers are showing nothing... I'm going to have a look at the manual and see how the bumper / switches work and try to determine the problem. I'll also reseat connectors on the main board. Hopefully I can find the problem soon.

Lets talk about power for a moment as well. If I am reading the manual correctly, I should get 50 VDC at the flipper coils right? I have my DMM set at 200 vdc and can't seem to find any voltage at the flipper coil lugs no matter what combination i use my leads on the lugs... Is this right?

Update - Bumper switches are good too, I just wasn't testing them right...

I'm starting to think this is some sort of power issue... Couldn't get any of the problem solenoids to fire when jumpering the lugs.

This is going to be a total newbie question, but the power lug is the 3rd or right lug correct?

I guess it depends on how you are looking at it

Power is testing good at the flipper coils... I wasn't using a good grounding location. Now that I am using the grounding strap inside the cab I have 70 VDC at the power lug of the coil. When I jump the ground lug on the coil, the coil fires and the flipper flips... so that rules out a power issue for the flippers.... Can I safely test the other coils the same way? Bumpers and kickers only have 2 lugs?

The thinner wires are the blue wires with the different secondary colors. They go back to the aux power board. Those are grounds correct?

Right but I was referring to the other coils that have the 2 lugs. I have continuity all the way up to the aux power board from them.

Ok, all coils fire when manually grounded... So you would you think there would be an issue with the aux power driver board?

all coils fire when manually grounded... Schematics show that the transistors in question are:
Left Bumper: Q75
Left Kicker: Q71
Right Bumper: Q73
Right Kicker: Q69
Lower Bumper: Q77

All tested around .555

Also found this in my research that I thought was interesting:

The Six Special Solenoids.
Williams' ROM software originally did not have CPU control of "special solenoids". These six solenoids includes the pop bumpers, kicking rubbers (slingshots), and kickback solenoids, and sometimes other coils. The original theory behind this was these items needed instant response. Having them controlled by the CPU would add enough of a delay to slow the solenoids down. After all, the CPU had to sense a switch closure of a pop bumper, then turn on a transistor which would fire the pop bumper coil. All this while the CPU was doing all the other chores it does (like scoring and controlling other devices). It was thought that this would not happen fast enough for good game play.

all except lola switches... which is the very last problem I want to address... I need to address flippers and bumpers / kickers first.

And yes all fuses are good - double checked even though all solenoids were getting power...

I rechecked the transistors... getting .469 consistently... the .555 is on Q79 which isn't used for any of the problems. I have more research to do but am all ears for any more advice that can be shared!

I appreciate everyone help this far! I am working on the issues in this order:

1. Flippers
2. Special solenoids
3. Lola switches / targets

Some test / info may be beneficial for multiple issues so I am trying to post as much info as possible.

I feel like I am hitting dead ends in all areas though.

First power. Flippers have power. They fire when manually grounded. Flipper buttons pass switch test. Wires have continuity all the way back to the interconnect boards.

What would you check / test next focusing on the flippers?

wayout440 stated "check for flipper voltage at the flipper cabinet switches...if you have it there,"

Does that mean at the flipper buttons? I wouldn't have VDC voltage there would I?

Ok, that makes perfect sense... I tried manually grounding the flipper button switches and both flippers fired. so that eliminates that question.

Ok, checked this morning and I do have continuity back to the #19 connector on the CPU board...

One thing I found odd though is that no matter which switch my alligator clip was on (left flipper button or right flipper button) I had continuity at both wires on the CPU connector.

(Actually if I am reading the schematic above correctly, it looks like this is by design)

If thats normal, then I guess the K1 would be the issue? I'm going to read more about that.

Thats what I plan on focusing on this evening after work... when entering diagnostic mode it should click closed. If I do not hear / see the click, I plan on pulling the board and possibly reflowing the solder... If I still see the same result, is there a way to test the relay to confirm if its good / bad?

Also looks like the transistor at Q67 is a common fail point too, I'll be double checking that per your message above

And the Q67 should read somewhere between 100 & 300 if it is good correct?

Thanks! I hope one of these are the answer... I'll be on it this evening!

I did not see any acid damage... I'll take another look tonight though

Manually grounded D3 and heard the relay click... flippers work when pushing the flipper buttons... This is what I was afraid of, because at this point the rest of the instructions don't make sense to me... I don't have a logic probe, which I am guessing is what is being referred to as pins and high / low and such...

Can anyone please explain the next step of action?

ok, lets start with the transistor... using my DMM on the ohm setting, when measuring with red lead on base and black on collector, I get .687 from base to emitter I get .691

For testing pin 10 of U50, I need to have my DMM set to VDC 20 with red lead on pin 10 of u50 and black goes where? This is with the game powered on? coined up? Sorry for not know this.

Here is the area I am working in. Just wanted to post to see if anyone could see anything that looks odd. I see pin 10 is right at the 0 in U50...

IMG_20150121_220652747.jpg

Ok, completed some tests... figured it would be the same as testing arcade PCB IC voltages...

Set the DMM to 20 VDC - Grounded the black lead and put the red lead on pin 10 of U50

Seems very low... started at .08 volts and fluctuated down to .07 briefly back and fourth during game play.

Would this mean that U50 is bad?

You were right, I was on diode test...

After re-testing on ohm settings, I think this very well may be the issue...

With my meter set to the 20 ohm setting, and leads not touching anything my meter shows 1 which should be the equivilent of OL... Using any combination of red / black leads on the B/C/E I am still getting a reading of 1.

So that should confirm that the transistor should be the issue correct?

Yes I figured it was the same as testing arcade pcb IC's...

About the posting above with the transistor info, does it sound like this is the problem?

Ok, I'll get on that... How about those readings from U50? Seems low right?

Would you suggest replacing U50 while I have the board out / soldering iron hot?

ok, with the flippers on hold while I wait for parts now, I am moving to the other solenoids: 2 kickers / 3 bumpers. All of them fire when manually grounded... have continuity back to 5J7 on the aux power driver board... I'm looking to see what could cause this... More reading! Any ideas / info is always appreciated!

Great - I'll do all that this evening... Thank you so much for your assistance!

Ok, grounding the transistors manually does fire each solenoid...

Question about the connectors... The image above shows the connections at 1P19

However on the board there is only a 1J19 (which doesn't have continuity to these) Am I looking in the wrong place?

Ok so the latest is I have continuity to the plug from all three bumpers but not from the 2 kickers... Blue / red and Blue / yellow... Nothing... I havent dug into the wires yet but is it possible that this is the reason why none on that plug work? Including the flippers which are 1 & 2 orange wires on this plug?

IMG_20150122_205934069.jpg

I think I may have found an issue...

See my picture... All wires come from the solenoids to the j7 connector on the aux pwr drvr board. Through the 4 diodes. The J3 plug goes the the 19 plug on the CPU. I have continuity from each wire on J3 to the corresponding wire on plug 19.

Here is the issue... The 4 diodes (D17, D19, D20, & D21)

17, 19, and 21 have continuity through them both ways. D21 is the only one doing its job. Do you think this could be the issue? Also, I have continuity from each solenoid to the corresponding plug on j7.

IMG_20150122_221900267.jpg

Also I have continuity for the bumper wires from J7 (where they come in from the solenoids) over to the 19 plug on the CPU, however I do not have continuity on the kicker wires on J7 over to the 19 plug on the CPU.

Yes, grounding each transistor on the MPU fires the coresponding solenoid for the pops and slings...

Ok, so that eliminates any confusion... So what do you think is the next step?

All the transistors test within range... Looks like yet another logic problem which is where I am totally lost lol.

I have not yet had the chance to start testing logic for the special solenoids, but had a question about the flipper work I am about to undergo... The transistors / IC should be arriving any day now... Do I need to replace all parts in that section? Resistors, D3 diode etc? The d3 diode seems to have continuity in both directions so that is no good.

I appreciate everyones assistance. It looks like I have reached the point were I know all of the problems are on the MPU board and before I go destroying the board changing IC's, transistors, and such... I think its time I send this board off to someone with actual experience working on them. I have certainly learned alot from this thread and I thank everyone for their help!

Has anyone had experience with Coin Op Cauldron?

Just to give an update... Clive at Coin Op Cauldron is awesome. Under promised and over delivered!

Board is back and working as it should now!