This topic was started as a private message. Below is the start of private message.

Hi Grumpy, after working with you on my high speed, i was hoping you could help me gain some insight with another issue i wanted to take care of.

Im not sure if youhave the time, but just incase, here is whats going on:

A few months ago, i bought a WPC-S ROADSHOW.

1 of the solenoids #11 “TEDS EYELIDS UP” was not working.

I disassembled ted, the lids up coil was bad so i replaced the coil for the eyelids.

I checked its transistor Q54. I buzzed out the tab to ground, and it buzzed as bad.
I also tested its legs, which also tested bad.

I replaced Q54 reinstalled the board, and it is still energizing SOL 11 when it shouldnt.

Teds head has a plug which i unplugged so i dont burn out the new coil.

I just tested the pre driver Q53 and it seems to be good.

According to my research, there is a chip ttl 74LS374 that could possibly be bad.

I read that i can put my dmm in diode test with the red lead on the ground leg, and the black on the others. They should test .4-.6 except for the power leg.

I was hoping you could help me figure out which chip it is, and which leg is the power leg.

I have a pic of the pinouts for the chip but cant seem to post it in this message.

It looks like 10 is ground, 1 is input control or OE, 11 is clock and 20 is Vcc.

Also i was wondering if there another way to check to see whats causing the issue, or if i should use my new logic probe somehow. Thanks again for your time. Sparky

**************************Grumpy replied**************************

Hey Sparky, hows things going with you. Here is a tech tip I learned the hard way. Any time you have a shorted driver, you always replace the shorted driver, predriver and diode and also test the coil for the correct ohms. This only cost you an additional .60 cents in parts and will save you lots of time and frustration.

Now on to your problem, U-4 is the LS374 that needs to be tested.

Pin 5 of U-4 turns on Q-53 by going high.

So use your logic probe and see if pin 5 is stuck high, if it is then you will need to replace U-4.

If it is low then you have a broken trace between pin5 and the base of Q-53.
It can also be a bad solder joint on Q-53 or pin 5 of U-4 causing it to seem like a broken trace.

The last thing is if pin 5 is low, then Q-53 can be bad even tho it tested ok.

D-22 should also be replaced as it is the diode for the shorted coil you changed.

Hi grumpy, things are ok here for the most part, how about you?
thanks for taking the time again to help out.

I just attatched my logic probe to TP2 5v & TP5 ground.
I tested U4 pin 5 as you suggested, and it is hi.
However, i tested pins 2-9 and 12-19 they are also hi. The legs marked with a “D” get a beeping hi tone, which seems normal.

The rest of my solenoids work correctly, so
I also checked all U3 pins and It tests exactly the same as U4.
It seems like hi is normal for pin 5??

I tested during coil 11 test mode, and game over mode since it is always locked on. Same results for both.

Which mode should i be in while testing? Thanks. Sparky
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Hi cyclone, only that coil has a problem. The rest of the game works flawlessly.

1. Coil is new.
2. No diodes on that tiny coil
3. Pre driver transistor tested good but i didnt replace
4. Main transistor is new.

Thank you cadillac, and pin guy for your responses.

Pin guy, thank you for taking the extra time to highlight the diagram for my problem.

I am new to a logic probe, but can follow directions very well.

So i am still taking baby steps.

According to what you stated, i believe my chip should be ok.

Can you please tell me which leg to test for the lo coming into the Q53 pre driver, and which leg to test for the hi coming out? Is it safe to test all 3?

You say base should be lo, so i believe i should get lo at the middle.

Also which legs should be hi/lo on the Q54 driver?

I am guessing that i could put my probe on J127 &129 to check if it is lo or hi if i am safe to do so.

Can i screw anything up with the logic probe?

Thanks. Sparky
97B54598-826D-4D1A-B915-DC921D677B13 (resized).jpeg

8529E70F-949F-40DF-9CF9-7140F8FEFC19 (resized).jpeg

Hi Grumpy, thats ok, im not sure if im going senile too, but i definately think im losing my mind.

Thanks for the added info.

And pinguy, thanks for the coin door tip.

During game over mode,
Pre driver Q53 tests as follows.
Pin 2. Hi
Pin 3. Lo

I get the same results testing other non issue pre drivers, in addition to what grumpy said, i think the predriver is good.

And Q54 as follows
Pin 1. Lo
Same as other good tip 102’s

Pin 2. Untested at this time.
Dmm set to DC?
Red lead on Q54 center or metal tab.?
Black lead on braid?
Coin door closed?
Reconnect coil 11?

Just trying to be extra careful. Thanks all Sparky

Ok grumpy, so it seems the Ttl chip is good, and pre driver is good.

I actually gave the tip 102 a test before installing, but i guess it could still be bad.

Is there a possibility that my soldering wasnt sufficient, or does that not apply here..?
i read something about the center leg needing to make contact on the component side, and if not, the coil will fire once, then blow the tip 102. Mine has fired more than once, but i kill power to it each time so it dosnt burn up.

I tested the tip102 for continuity after install, leg 1 and 3 were good, and leg 2 was good on the solder side. I didnt notice a component side trace to check on leg 2, but i read about it since then.

"""""" if the new TIP102 transistor is not soldered in correctly, this can cause the
TIP102 to short again. This happens because the old TIP is hastly removed,
destroying the plated-through holes in the circuit board. After soldering the new
transistor, make sure all three transistor legs are connected to their traces. Use the
continuity feature of a DMM to test this. Particularly if the center leg does not
connect to the 1n4004 diode (trace on the component side of the board), the
TIP102 will work for one "fire" and then lock-on during game play and destroy itself.""""""

mine was locked on upon power up, before game play was started, if that makes a difference...

i will check this continuity tomorrow...

I will test tomorrow like this:

Coil disconnected
DMM on ohms
Red on tab
Black on braid

Thanks. Sparky

Ok. I just did my tests.

First i checked for continuity from the tab to the diode, and it is good.

I then cheked the ohms of Q54.

Game in attract mode
Coil disconnected
Coin door closed
Dmm set to ohms
Black on braid
Red on tab
Reading was 4.20

I tested the transistors for the other 3 TED coils that are currently disconnected by the same plug.
Q52,56,58. They all show OL on my meter.

Does this confirm that the new transistor is bad?

Im honestly very confused by my readings since im getting OL on my good tips.
I should be getting the reading grumpy stated on my good tips.

I have to admit, that i dont use my ohm setting to often.

I have 2 meters. One is auto ranging, and the other isnt.

I keep retesting with both meters.
With coin door closed:
i am getting OL on the auto ranging meter, and
1 on the non auto ranging on every available selector switch setting.

With coin door open:
my auto range gets about
1.6 Mohms on Q52,54,56,58

MY manual select meter on 2000k setting shows:
Q52. 1111
Q54. 1045
Q56. 1041
Q58. 1151

Am i testing correctly?? Im confused.
Thanks. Sparky

hi grumpy and pinguy.

I just checked J129, and it has nothing connected to it.

to be clear, the statement quoted in pinguys last post was actually quoted from grumpy, but i had pasted it into my first post so it may have looked like mine.

earlier today, before you made your last 2 posts, i decided to replace my tip102 again.
i decided to only replace that one transistor as to not introduce any new additional problems, by messing with more of the board.

i figured i can still replace the diode and pre driver after i see what happened.

so after replacing the Q54 transistor, i plugged ted back in,
turned the game on, and the eyelid up coil would lock on momentarily, then released.
but then the eyelids would close and work properly during gameplay, and test mode, but the occasionally lock on again.

i think the first transistor that i used may have actually still been good, and was just locking on intermittently, but i never gave it a chance to not lock on.

so something is obviously still wrong.

i disconnected ted again, as to not burn up the coil.

not that it means much, but the game did not seem to be abused before i got it.
i think it may have been only used in a home. it was dirty, but it cleaned up very nice.
still has all matching serial number boards, and they all looked untouched.

there are barely any marks on the game, in other words, it was not a basket case..

where do i go from here/ thanks//sparky

ooopss

i just did this test:
game off
meter on 2000K ohms
one lead on metal tab.
other lead on non striped side of D22 diode.
reading was 000

i did not replace the diode, but i see that the stripe is on the RIGHT side of the diode.
that is the same side as Q52,54,56 in the same column of transistors.

yes, the game is now beautiful otherwise.

i will give this a try tomorrow. im heading to bed now.. ill report back..thank you...sparky

Ok, i just flipped the ribbon cable at J113 to the Cpu.
The problem is still intermittent.

Similar to the way a fuse can be substituted with a circuit breaker so you dont go through a handful of $1 fuses during diagnosis, Im curious if there is a way to substitute a coil with a buzzer or something so that you dont blow through $11 coils during tests. Mine is starting to overheat a bit.

Thanks for your help. Sparky.

Since its a bit dangerous, Ill hold off on that for now.

Anything else i can check? Thanks

Thanks again zaza.

Before i try your test light setup, i will test the resistors and diode and see what i get.

Thanks. Sparky

ok, i just tested all the resistors and the diode for sol 11.

below are the values.
all tests are in circuit, but the coil is disconnected by its plug.
power off.

r90 .477 kohm
r91 4.80 kohm
r92 2.035 kohm
r93 68.1 ohm

d22 .344 tested in circuit

i did some comparisons, and i have an idea of what might be going on, but id like to hear from you guys first to confirm.

thanks///sparky

Yes zaza, thats exactly what i had thought.
The reading appears low, plus my other 3 Disconnected TED coils had diode readings of about .555, so this one stood out as likely bad.

Grumpy said that he always replaces the diode with the 2 transistors. Now i understand why.

I will swap it out, and report back.

Thanks, sparky

Lol, ive got to see if i have the pre driver on hand. I have a handful of 2n4401’s. I thought they would be the same as my high speed, but they are not. Sparky

Sorry, ive been very bust the past few days.

I picked up the correct pre drivers.

I removed the driver board, and noticed that Q54 leg 3 (emitter) looked blackened.

I tested for continuity, and noticed that the tab/leg 2, and keg 3 had continuity.

So i replaced Q 54 again, along with Q53, and diode 22.

Afterwards, i noticed that the Q54 still had continuity between leg 2 and 3.

I removed Q54, and i still have continuity on the board from hole 2 to hole 3, with the board out of game.

I am no expert, but i have a good feeling that this should not be.

I dont see any solder connecting these two holes on either side of the board.

Can you guys please confirm whether or not these two should have continuity or not?

Also if they should not, what else could i check to see why these two holes have continuity.. thank you all. Sparky

I just rechecked this over and over, and i dont see anything.

This side also seems to be free of any unwanted solder.

I am getting contact all the way from the right side of R92, all the way down to J129-4.

I dont visually see anything causing unwanted contact.

I have to also note, tgat my meter has an audible tone for continuity.

I have noticed that it seems to tone for a moment, then pause for a moment, then tone.

Tone-pause-tooooooooooooooone.

This happens about 9 out of 10 times, which is not the norm for my meter.

Could there be something else causing this continuity?? Thanks. Sparky

Hi grumpy, here are pics of both sides.

The component side got a little charred looking between hole 2 and 3.

Solder pads 1 and 3 on the back separated after the 4th removal of Q54. Thanks. Sparky

99E3AB72-823D-4155-81EF-2A9A409EED96 (resized).jpegFA5F8F22-7118-4305-9E1E-845EC4A37C51 (resized).jpeg

Sorry to keep everybody in suspense, ive been very busy.

I scraped away some of the black with a toothpick, and the continuity stopped, so that was the issue.

Thanks for the suggestion, I never knew that could be a cause.

What is the best way to make sure i remove enough or nuetralize to make sure it does not re-occur? Thank you.

Thanks grumpy, ill give that a shot.
What is a good way to handle the solder pads on the rear since they do not have any traces?

The trough hole on the center hole has continuity as it should.

Also, the mask is partially missing on one of the traces (see pic). Is this a concern, or should i cover with something?
Thanks again. Sparky.

Hi pin guy, thank you for the additional info. I will check out those links.

Im not sure if i explained correctly, but i believe my center hole is fine because it is making contact through the board as it should.

The left and right hole are just missing the pads on the solder side, so i think the eyelet isnt needed in my case??

Is this correct? Thanks. Sparky

Ok, i understand. Thank you grumpy and pin guy for clarifying.

I will look for the replaacemant pads, and hopefully that will be the end of this issue.

During this whole process, the mini coil in Teds head got a bit overheated.

The wrapper got a little funny, but the plunger still slides through.

Out of curiosity, can this coil condition cause any further issues?

If so, i dont waant to put the board back in to test before i change the coil.

Thanks. Sparky

Hi grumpy, thanks for the link.sorry i couldnt get back here sooner. Very busy with alot of things plus a lot end of year school stuff with my kids.

I took a look, and my coil in question is not listed.

I looked for similar numbered coils, and found 2, but neither have a resistance listed.

SM-31-900-DC

I stopped into my local electronics shop, but he does not have the solder pad set like you pictured.

I will keep looking. Thanks. Sparky