Jurassic Park Coils going CRAZY

vikes5

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After swaping out a bad rollover in the control room (works now) the solenoids have started to go off unprovoked. To be specific it's the thumper, ball loader, two up-kickers and the T-rex return. They all fire during game play unprovoked and even after game is over. Seems to be associated with the flashers or when going into multiball. Also when flashers are activited in DIAGNOSITCS the coils seem to fire as well. Checked all fuses and connections. HELP !!!! please.

All other coils (flippers etc.) working fine. Chased the wires (purple) and they all lead back to the PPB board. Running out of ideas.
 
Do they go off randomly all at the same time, or do they each go off one at a time randomly? Any other pattern to their firing?
 
Your left right relay is bad I assume. There is a relay on the CPU that allows transistors to control two banks of items. On one side is flash lamps, on other side is coils.

Your coils are firing when the machine is actually wanting to fire flashers.
 
Your left right relay is bad I assume. There is a relay on the CPU that allows transistors to control two banks of items. On one side is flash lamps, on other side is coils.

Your coils are firing when the machine is actually wanting to fire flashers.

Good call. I would definitely check that first. IIRC on a Data East game the relay contacts would be stuck closed for those symptoms and a Williams game would have the relay stuck open.
 
I originally thought it was a ball search also but I don't think so. They all seem to go off randomly sometimes several times back to back on the same coil.

The coils don't seem to be firing at the same exact time but more in some random sequence; however, they go off so quickly that it is truely hard to tell.

Thanks for the advice. I will look into that relay you guys are referring to on the CPU board. Kind of a noob with electronics but trying to learn.

Any other theories would be appreciated.

Thanks
 
They go off so quickly because flashers are switched on and off very quickly during some parts of the light show. Don't run that machine until you get it resolved, otherwise you could damage your coils.

Here is the section of pinrepair.com that explains the L/R

First Test the Solenoid L/R Select Relay!
When the solenoid A/C select relay is not working correctly, there can be all kinds of coil problems. A malfunctioning L/R relay, if stuck on or off, won't give any power to either the coils or flashlamps. If the relay is constantly energized (stuck on bank "R"), it's probably because it's driver transistor Q29 is shorted on.

On most DataEast/Sega games, the "L" (or "A") bank was for coils, and the "R" (or "B") bank is for flashlamps. But on games from Time Machine to the Simpsons, this logic was reversed. In these games the "L" bank was used for flashlamps (instead of coils), and the "R" bank was used for coils (instead of flashlamps). Keep this in mind when diagnosing problems.

The first thing to do is to test the solenoid L/R select relay. Turn the game on, and enter diagnostics (entering diagnostics should de-energize the L/R relay; on some games the L/R relay will stay energized after finishing a game because of an after-game flasher light show). Take an alligator test wire and connect it to the metal tab on transistor Q29. Then with the game on and in attract or diagnostic mode, touch the other end of the alligator clip to the ground strap in the backbox (WWF Royal Rumble and later, make sure the coin door is closed). The L/R select relay on the PPB board should click "on and off"; it will click on when the transistor is grounded, and off when not.

Another way to test the L/R relay is find the 1N4004 diode next to the L/R relay. This is the blocking diode for the relay. If the Non-Banded side of this diode is grounded using an alligator test lead, this will also energize the relay. On games with PPB boards, remember the L/R relay is mounted on this board (and its diode is right next to the relay). On the first two DE games that don't have a PPB board (Laser Wars and Secret Service), the L/R relay (if the games have one, I'm not sure!) would be mounted under the playfield.

If the relay "click" is not heard, do a quick test of transistor Q29 using a DMM:

* Turn the game off.
* Put the DMM on ohms (buzz tone).
* Put one lead on the ground strap in the backbox.
* Touch the other lead to the metal tab on transistor Q29.
* If the DMM shows zero ohms (buzz), the transistor is bad! (shorted on). This bad transistor will cause the L/R relay to stay energized.

The Q29 transistor can stay grounded for a period of time. This will not ruin the transistor or the relay. Do not leave Q29 grounded for more than a few minutes. That should be plenty of time to test any coils.

If for some reason the L/R relay itself is bad, it can be replaced at mouser.com part number 653-LY2-0-DC24 (NTE equivalent is R14-11D10-24P).

Low Coil Voltage.
Another problem is that the L/R relay can have pitted contacts on its switches. This can cause some resistance, and lower the coil voltage. If testing the coil voltage at the coils shows less than 50 volts or 25 volts DC (depending which voltage the coil uses), the L/R relay should be checked. Often the plastic cover that goes over the relay can be removed, and the switch contacts gently files. Also check for cold solder joints on the relay solder points. Also keep in mind that the 50 volt coil voltage will usually test at 70 volts (because there is no load, and the voltage is unregulated). The 25 volt system will often test as high was 38 volts.

Is the Solenoid L/R Select Relay Bad?
Be aware that relays can go bad too. This can especially happen if transistor Q29 locks on for an extended time, and leaves power to the relay turned on. The relay can actually get so hot, it burns the relay contacts together. Sometimes the solder joints on the L/R select relay can go "cold" or fatique. This often will make an L/R select relay not work (but reflowing the relay solder joints can generally fix this).

Wrong L/R Relay installed on some TftC Games.
During production of Tales from the Crypt, the wrong L/R select relay on the PPB board was installed. This caused solenoids to activate randomly, and flash lamps to not activate at all. The problem was the PPB's K-1 relay was installed with a 24 volt AC relay, instead of a 24 volt DC relay. The incorrect AC relay has a relay coil winding of about 2 ohms, while the correct DC version is about 650 ohms! The lack of ohms will cause the relay to burn and fail. The relay can be identified easily because it is labeled "24v AC", while the correct relay is labeled "24v DC" (or the relay's winding can be measured with a DMM). Games with serial number 101664 or later have been inspected for this problem. If this 24 volt AC relay is installed, replace it with the correct 24 volt DC relay. This was mentioned in service bulletin number 52.

My bad, it is on the PPB board. The one on the circuit board locks out flippers (I think).
 
Thanks for all the great info. I plan on running those tests when I get home today. Great informations....Thanks!!!
 
Swapped out the rely and seemed to correct the problem. Thanks for all your help.
 
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