Help with WPC 89 Driver Board Repair.

[Rick471]

Hi all 1st post so be gentle as I am fairly new to the pinball scene.

i have a Whitewater that has a very annoying problem with the Bigfoot Diverter.  I have done quite a few steps but I cant seem to fix it.  Hopefully someone here can help?!

Let me preface by saying I had just purchased the machine and didnt realize it had anything wrong with it until after about 20 plays I realized the diverter had not activated in ANY of my games.  I pulled out the manual to check if there was a problem at connector J130.  I noticed Pin 7 was burned.  So I decided to replace the header and pins at J130.  When I pulled the connecter I saw there was no wire going into the connector.  I looked at the harness and saw the wire had been cut off and taped over.  Obviously, someone realized the same problem and decided not having the diverter function at all was the best solution...

So, instead of attaching the J130-7 wire to the rest of the J130 connector I decided to, temporarily, put that wire on its own connector until I repaired it.  That way I could still play a few games here and there, as is, if I couldn't immediately repair it.  So I plugged in my new J130-7 connector with only the one wire attached and BLAM!!, Bigfoor Diverter activates and starts smoking really badly.  I shut off the power and began some testing...


I am 99.9% sure that I have an issue with the board at J130-7.  As soon as I power up the machine the diverter activates giving full power to solenoid.  I made up a test led and attched it to the 5v TP2 and J130-7.  It also lights up as soon as I power it on, therefore, my problem is on the board and not a short in the under playfield wiring.

I replaced the following components (all at the same time), Q66- Tip36c, Q65- Tip102, D26 1N4004 Diode, Q60- 2N5401, and U5 - LS374...

I also replaced the coil at the diverter since the old one burned up!

So now I am at a point where I do not know what else to do.  I have checked continuity on the circuit and it seems to have it where it should.  But other than that I am at a stand still with the board and very frustrated.

The rest of the board works fine when connected.  Just the diverter is the issue. 

Any help from those more experienced???

Thanks, glad I found this site - Rick

[Homepin]

Hello Rick & welcome,

So you are saying that even AFTER you replaced all of the parts the power is still applied to the solenoid coil ALL THE TIME?

If that's the case it is possibly time to start taking some measurements with a meter - what voltages are present on the base of the output transistor (TIP36C) and the driver to it when you power up? Thi sshould give a clue as to which direction to look - further back from the transistors or further forward in the wiring harness etc?

[Rick471]

Yep still gets power applied instantly.

I will check voltages now, havent done that yet.  

Ground lead on dmm to ground braid?

And which leg of the Tip 36 and Tip102 do I put the positive on?

Sorry, hadnt read up on how to test those with power on yet..

[Rick471]

Soooo,

I found something interesting.  I dont know what is going on now.  I am very confused!

I checked voltage at J130-7 pin and it was nothing.

I then plugged in the Purple/Yellow wire that I wired up by itself with a new connector I get 78VDC on it where the wire would connect to the coil!!

Confused...

[Homepin]

The way the solenoids work is as follows:

+ voltage is applied to one side of all coils - this is why you need to take care when working under the playfield with power on. As you have measured, 50~80 DC volts is typical.

The transistors take the OTHER side of the coil to ground thus applying the voltage across the coil.

You will measure full DC coil voltage at the connector of the PCB when the game is switched on as the TIP36 grounds this wire to activate the coil.

The FIRST voltage you need to know is the base of the TIP36 - this is leg number 1 (the one on the left looking at the face of the transistor with the writing on it).

It should be ground or VERY low - maybe 0.1V with the ground lead of your meter connected to the braid inside the backbox.

[Rick471]

Ooookay, thanks for the lesson, I understand a little better now. 

So I measured the left leg of the Tip36 and it reads .575V.

Looks okay?

[Rick471]

So I didn't want to for fear of ruining another board, but I swapped the board from my Jackbot to the Whitewater.  The diverter works perfectly.  I now know for sure there is some sort of short in my board.

Now I just have to find it!

[Homepin]

Ooookay, thanks for the lesson, I understand a little better now. 

So I measured the left leg of the Tip36 and it reads .575V.

Looks okay?

A TIP36 will be fully switched ON with 0.5V on the base (left leg) - this is why the coil is activated.

Your problem appears to be further back up the chain. Look at the driver to the TIP (the transistor before it) and measure its base - again it should be very close to ground - then look at the parts further back for a clue - I don't have a circuit in front of me but this section is pretty basic and you should be able to track back.

You say you have replaced all of these parts? Any shorts between pins? Are they all inserted the correct way around? Were any substitutions made using parts that MIGHT have a different pinout?

[Rick471]

Hmm, okay, I will check the Tip102 and N5401 next.  These are all PNP transistors correct?

The schematic doesnt specify...

[Homepin]

If the arrow faces OUT it is NPN - if the arrow faces IN it is PNP

TIP36 is a PNP

[Rick471]

Ok,

The arrown on the WPC Schematic for Tip36c and 2N5401 points IN so PNP.  The manual also says PNP for thses two.

BUT, The Tip 102 is drawn differently on the schematic.  It shows two OUT arrows on the left side.  Why two arrows?

Does this make it a NPN?

[Steevsee]

Hi Rick.
Yes, TIP102 is NPN

[Homepin]

Ok,

The arrown on the WPC Schematic for Tip36c and 2N5401 points IN so PNP.  The manual also says PNP for thses two.

BUT, The Tip 102 is drawn differently on the schematic.  It shows two OUT arrows on the left side.  Why two arrows?

Does this make it a NPN?

TIP102 is a "darlington" transistor which is basically two transistors fitted inside the same case. That's why the drawing shpws 2 arrows - if you look closely you should see two transistors drawn there and, as Steevsee said, TIP102 is a "NPN Darlington Transistor"

This pin connections are the same as the TIP36 however with the base (or drive if you like) leg the one on the left.

[Rick471]

Holy!!!

I believe I have installed a PNP.

I tested it out of curcuit and placed black lead in the center.  Both outside legs get .48v and .5v respectively.

Or are all Tip102's npn???