1986 sys 11 high speed police light not working


By SPARKY70

5 days ago


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  • Latest reply 4 days ago by SPARKY70
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#1 5 days ago

Hi all i got a high speed a few years back, and when i bought it, the police light was ALWAYS on when powered on. To save the motor from burning out, i unplugged the motor/light.

I played the game without the beacon light since then.
I finally have The time to look into fixing it.

The police light motor/ light operates as solenoid #4, although it is not a solenoid.
The light uses transistor Q24, and pre driver transistor Q20.

Originall i tested only Q24 and it was bad, so i replaced it.

After putting it all back together, it didnt fix the problem, so today i tested and replaced predriver Q20, and retested Q24 from .4-.6 volts, but the light still does not run.

The light is controlled through J11 pin 5 grey/yellow wire.

The grey yellow wire runs up to a small wafer type board next to the light.
The board has a diode and a ceramic resistor on it.

It then sends the signal to a relay next to the board through a greywire snd a brown wire.

When the signal is received, the relay closes, then sends power to the light by two red/white wires that connect to the police light.

There is a fuse on one of the red/white wires, and the fuse tested good too.

When i bypass everything, and touch the pair of red/whit3 wires together, the light lights, and the motor spins.

This means that the motor, bulb and red/white wires are all fine.

When i operate the relay using a 9volt battery, the light and motor work fine too, so i believe the relay is fine too.

I checked continuity of the grey/yellow wire from J11 pin 5 to the wafer board, and continuity is good.

Now, before i test the diode and ceramic resistor, Id like to check the output of the grey/yellow wire from J11 pin 5 to the wafer board, but not sure how to do so.

If anybody can tell me how to test this id appreciate it.

If i left anything out, just ask.

All other solenoids/flashers/lighting are all fine. Only the police light issue. Thanks. Sparky

image (resized).jpeg

#2 5 days ago
Quoted from SPARKY70:

If anybody can tell me how to test this id appreciate it.

First off I must say that you described your problem very well.

Now on to your question, you can test the grey/yellow wire a couple of ways. You can use an ohm meter and check the resistance from 1J11 pin 5 to the wafer board. It should read 1 ohm or less. But the easiest way is to use a jumper wire with one side connected to the ground braid and then touch the other end to the metal tab of Q-24 transistor. If the light turns on then you know that the wiring and relay are both working correctly and you still have a board issue. If it doesn't turn on then use the jumper on the wafer board and touch the grey/yellow wire, if it turns on now then there is a break in the grey/yellow wire. If it doesn't turn on then check the cement resistor for an open.

#3 5 days ago

Hi grumpy, thanks for your help. I just found your response as i am going to sleep. I quickly used my dmm set to ohm and checked pin 5 to the wafer board. If im doing it correctly, It seems to be 0.3 - 0.0

My jumper wire is out in my garage, so ill get to that tomorrow.
If i understand correctly, i put one end of the jumper on the braid, and the other on the Q24 tab. If the light assembly works, there is a bourd issue, if not, its after the board.

Some questions:
When you say put the jumper on the grey/yellow at the wafer board, is the other end still on the braid?
I think my continuity test from pin 5 to wafer confirms that the wire is good?

And
How do i check that resistor for an open?

Thanks. Sparky

#4 4 days ago
Quoted from SPARKY70:

If i understand correctly, i put one end of the jumper on the braid, and the other on the Q24 tab. If the light assembly works, there is a bourd issue, if not, its after the board.

Yep.

Quoted from SPARKY70:

When you say put the jumper on the grey/yellow at the wafer board, is the other end still on the braid?

Yep.

Quoted from SPARKY70:

I think my continuity test from pin 5 to wafer confirms that the wire is good?

Yep.

Quoted from SPARKY70:

How do i check that resistor for an open?

Check it just like you checked the grey/yellow wire except it should read @ 100 ohms on the meter.

#5 4 days ago

Hi grumpy, i just jumped the ground braid to the tab of Q24.

So acording to what you said above there is an issue on my board.
I am now assuming that my relay, wiring, ceramic resistor diode, etc. are all fine.

I also checked the ceramic resistor. The meter reads 136. Is that an issue, or irrelevant?

If thats all correct, what else can i check on my board? In the mean time, i will be reading up on this. Thanks again. Sparky.

#6 4 days ago
Quoted from SPARKY70:

i just jumped the ground braid to the tab of Q24.

Did the beacon light and turn?

Quoted from SPARKY70:

I also checked the ceramic resistor. The meter reads 136. Is that an issue, or irrelevant?

That is fine.

Quoted from SPARKY70:

If thats all correct, what else can i check on my board?

Do you have a logic probe?

#7 4 days ago

Yes, the beacon lit and turned when i grounded Q/4 to the braid.

I dont have a logic probe.

#8 4 days ago
Quoted from SPARKY70:

Originall i tested only Q24 and it was bad, so i replaced it.

After putting it all back together, it didnt fix the problem, so today i tested and replaced predriver Q20

I'm betting that one of the new transistors is bad. Or there can be a poor solder joint on one of the transistor leads. This is harder to test with out a logic probe but there are ways. When you place the game in coil test for the beacons it will pulse the transistors on briefly. This can't be picked up by a multimeter very well that is why its best to use a logic probe. Try using your meter on the base (middle leg) of Q-20. It should read less then 0.8 volts DC and then change every time the game pulses the transistor. See what you get.

#9 4 days ago

Grumpy, running test mode on coil #4 (police light), i just put my dmm on DC, red lead in middle leg of Q20, black lead on braid.
The reading fluctuates at around 60.0.

Am i doing something wrong?

I dont know anything about an osciliscope, strobe or logic probe.
Are they all the same thing?
I have been told i can use a Dmm with an HZ function for testing certain things.

Ill see what i can easily obtain locally. There is a harbor freight very close to me.
I know mist of their stuff is cheap junk, but i can have it in about 15 minutes.
Any suggestions?

#11 4 days ago

Ok. Just ordered that lp 560. Should have it in a few days. Anything else i can try till then? Will you be around in a few days?? Thanjs. Sparky

#12 4 days ago

Im always around. Once you have a logic probe this will only take 5 minutes to troubleshoot.

#13 4 days ago

Sounds good. Thanks

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