1986 sys 11 high speed police light not working

(Topic ID: 214854)

1986 sys 11 high speed police light not working


By SPARKY70

5 months ago



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  • 111 posts
  • 4 Pinsiders participating
  • Latest reply 4 months ago by GRUMPY
  • Topic is favorited by 2 Pinsiders

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There are 111 posts in this topic. You are on page 1 of 3.
#1 5 months 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

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#2 5 months 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 months 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 5 months 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 5 months 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 5 months 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 5 months ago

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

I dont have a logic probe.

#8 5 months 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 5 months 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 5 months 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 5 months ago

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

#13 5 months ago

Sounds good. Thanks

#14 5 months ago

Hi grumpy, the logic probe arrived yesterday. Please advise when you get a chance. Thanks. Sparky

#15 5 months ago

Put the game in coil test and lock on solenoid #4. Find U-20 and test pin 5, when in test the pia chip will put a high pulse on pin 5. When the CPU boots correctly the blanking signal goes high and pin 4 on U-20 is tied to the blanking signal and should be high. Pin 6 of U-20 is the output and should pulse high each time the pia chip pulses. The high pulses go to the base of the pre driver Q-20 which causes it to turn on and off. When Q-20 turns on 5 volts flows thru R-49, Q-20 and SR7. This applies a high signal on the driver Q-24 base turning on the transistor. This grounds the relay coil, turning on the beacon light and motor.

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#16 5 months ago

Hi grumpy, if i understand correctly,
Pin 4 should be high
Pin 5 should pulse high
Pun 6 should pule high.

Where do i put the alligator clips, im guessing back on ground strsp red to TP2??

Ill post the results after i test. Thanks. Sparky

#17 5 months ago
Quoted from SPARKY70:

Where do i put the alligator clips, im guessing back on ground strsp red to

Most system 11 boards have a 5 volt and ground test point on the CPU board. The red lead on the 5 volt test point which is in between U-21 and U-22. Black lead to the ground test point that is to the left of the batteries.

Quoted from SPARKY70:

Pin 4 should be high
Pin 5 should pulse high
Pun 6 should pule high

That is correct if your are in coil test mode on solenoid 4.
Let me know what you find.

#18 5 months ago

Grumpy, i found TP2, just as you were replying. I will give it a test.

#19 5 months ago

Ok,
pin 4 is high
Pin 5 is high/low, which i assume is pulse

Pin 6 is LOW.

#20 5 months ago

This can be one of two things, U-20 is bad or the pullup resistor SR6 is bad. With power off measure resistance on SR6 from pin 1 to pin 2 and then pin 1 to pin 3 and so on and so on. Pin one should be marked by a white dot. Each time you measure it should read @ 560 ohms. Does it read different when you check pin 1 to pin 5?

#21 5 months ago

Hi grumpy, pin 1 to 5 test seems to be wrong (113), all others 560.

#22 5 months ago

Do you have a pair electronic side cutters? To isolate between SR6 and U-20 I would cut pin 6 of U-20 in the middle. Then carefully separate in two and then turn on power and see if the beacons come any time the power is on.

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#23 5 months ago

Hmmmm, i have a cutter that may be small enough, but before i try cutting a leg, what happens if its the sr6 that is bad?

Would i also have to replace the U20, or something else?

Any other way to isolate?

GPE, is currently out of stock on the 7408.

This is a scary step for me. Lol. I am slghtly above beginner here.

#24 5 months ago

If cut correctly the leg can be repaired with a dot of solder. Are you capable of replacing either part? If yes then you should buy the correct cutters for part removal before desoldering. If you're not able to replace either of the two parts then you have gone far enough and should send it out with a note to replace both parts.

#25 5 months ago

If you live within a couple hours of me, take a drive and I can fix this while you watch in 5 minutes and then we can play some pinball.

#26 5 months ago

Hi grumpy, thanks for the offer. Infortunately i dont live close enough.
I am feeing i may br capable. Ive never replaced an IC before, but ive replaced header pins, and a couple of transistors.

Im may see q friend tonight that has likely done it before, and get some advice. He may even have the parts on hand.

He helped me once in the past, but i know he is very busy lately.

Would i be able to perform this last test if i took the board out, or would it have to be installed?

Thanks. Sparky

#27 5 months ago

No you would need to test with the power on. I test on the bench with a computer power supply.

#28 5 months ago

I figured it had to be in game.

I will probably give it a try. Ive got to start somewhere.

The way i see it, is if the 7408 is bad, and i cut the leg, worst case scenario, is that it still doesnt work even if i dont proceed further.

My main concern is that the legs are close together and soldering needs to be even more precise compared to the other stuff ive done.

Im probably worried for nothing, but want to be on the side of caution.

Ive got a digital temp soldering station.

When researchig temperatures for boards, It varied, but i think 650-675 degrees was the range most common.

Out of curiosity, what do you reccomend?? Thanks

#29 5 months ago
Quoted from SPARKY70:

Out of curiosity, what do you reccomend??

650 degrees is a good start and as you gain more experience you can raise the temp. I run @ 700 - 750 depending on what I am working on, but I have been doing board work for 32+ years now. I betting the AND chip is bad and causing the low resistance reading on SR6. With the correct cutters you will be able to snip the leg up above the board so not to damage the traces on the board. If you damage the chip beyond repair, doesn't matter as its a .50 cent item. I was also thinking that if you did cut pin 6 you can retest SR6 for ohms again and if all the pins test good you would know that U-20 was the problem and you would not have to power it back on for testing.

#30 5 months ago

So if i cut leg 6, and sr6 pin 5 is still out of whack, then St 6 is bad.

If i power on with leg 6 cut, and the beacon goes on, would U20 be Bad?

If the beacon stays off, Sr6 is bad??

Or the other way around?

#31 5 months ago
Quoted from SPARKY70:

So if i cut leg 6, and sr6 pin 5 is still out of whack, then St 6 is bad.

If i power on with leg 6 cut, and the beacon goes on, would U20 be Bad?

Yep.

Quoted from SPARKY70:

If the beacon stays off, Sr6 is bad??

Yep.

#32 5 months ago

Ok, ill have to buy a smaller cutter, mine is a bit too big.

Too bad its not an end leg.

Seems tight between the other legs.

#33 5 months ago

It takes a special type of cutter that is just for electronics like this one. These are only @ 4.5 inches long. And very sharp!!

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#34 5 months ago

Ok grumpy, i cut the leg today, and tested SR pin 5, and it is now the correct 560.

I also powered the game on, and the beacon turns on immediately as you described. According to above my U20 is bad.

Now i will get up my nerve, and replace my first ICchip.

GPE is out of stock on the 7408, but they have 74F08 in stock.

My chip does have an F on it, but not sure if that makes it the same or not.

7408
F

see pic.
Thanks. Sparky

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#35 5 months ago
Quoted from SPARKY70:

GPE is out of stock on the 7408, but they have 74F08 in stock

In this situation this is an OK substitute.

Quoted from SPARKY70:I also powered the game on, and the beacon turns on immediately as you described. According to above my U20 is bad.

I had a fifty fifty chance!

Quoted from SPARKY70:

Now i will get up my nerve, and replace my first ICchip.

If your nervous about doing it you can send me the board or you can practice on a junk board until your ready. You don't want to ruin a good board.

#36 5 months ago

Thanks for the offer. I think its about time to get my feet wet.

Im extra careful when doing this stuff, so i think id stop before i did any irreversable damage.

Since i am going to place an order, i have one other isuue with my displays, that i started looking into so i can order any parts i need together.

I believe its on the display driver board (resistor), and have been reading up on it. I could give you the whole rundown if youve got the time.
I appreciate all youre help with the beacon, and dont want to abuse your time and willingness to help.

Thanks. Sparky

#37 5 months ago
Quoted from SPARKY70:

and dont want to abuse your time and willingness to help

This is what I do for fun, so if I can help I will and if I can't someone else may have a fix for you. So ask away. Display issues will be a good test for the logic probe you purchased.

#38 5 months ago

You may want to remove the 1 amp fuse from the back box so the beacons are not on while testing.

#39 5 months ago

Lol, ive already disconnected the beacon plug.

Thanks again for your help. If you need any help with a pre computer car, im pretty good with those.

So with the displays, i have 2 segments locked on.

Segment "C" and "COMMA".

This occurs on player 1, player 2, and the MATCH side of the CREDIT/MATCH display.

You may be aware that these are all tied together, so i figure that it has to be something that controlls these 2 displays, and right side (MATCH) display. FYI, the match display does bot have a comma,

My displays are all crisp and clear, and work perfectly during test, aside from the C and Comma segments.

See pic, ignore the "8" on player 3 display. This was during display test, and was the best way to get an informative pic.

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#40 5 months ago

This is what they look like during gameplay and attract mode.

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#41 5 months ago

This pic is during the number 8 test.

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FYI all the other segments not shown work correctly on player 1 and 2.

#42 5 months ago

I have fixed many issues like yours. You first need to determine which board is the problem. Since this is on display 1 and 2 you will need to test the output of the CPU board at the ribbon cable. If you put the game in display test and lock it from moving just like the pic so display 1and 2 should be blank. Then remove the ribbon cable and test the pins with your logic probe. Note the readings.

#43 5 months ago

When i got the game, segment M was locked on, and i believe that the comma would come on with only certain letters anD numbers.

Resistor 34 was all burned up, so i replaced it about a year ago with what i believe to be the correct part.

M started to work correctly, and if memory serves me correctly, that is also when C Became locked on.

The resistor above (35), and below (37) also look burned up, but according to research, neither control the C or COMMA segments.

The remainder of the board looks to be in very nice shape.

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#44 5 months ago

I wrote the above post as you were writing your response.

After the new info i posted, Where should i start?? Thanks

#45 5 months ago

Start at the ribbon cable. Hard to read manual on my small phone but it looks like c is pin 21 and comma is pin 26. Lock the display so that a the top displays are blank. Then check these 2 pins.

#46 5 months ago

Yes those 2 resistors will need to be replaced along with R-23 too. But these are not your problem at hand.

#47 5 months ago

Good eye R23 was the only other one i saw that had a brown tone to it.

I confirmed with the manual that pin 21 and 26 are comma and C.

I will probe now.

#48 5 months ago

All test Low, except
16 has a wierd reaction, like interferance.
17 is HIGH, and
18 is the same as 16.

Im assuming 1-13 are the first row starting at the red line, and 14-26 are the other row. I see pin 1 and 26 noted on the board.
I assume they dont jump 1,3,5,7,etc.

#49 5 months ago

Can't remember off the top of my head. Im stuck at work until midnight. You can check to see which pin is the blanking. That should be pin #2.

#50 5 months ago

Testing low means its off like it should be. There will be a high pulse when the segment is turned on. Obce you double check the pin numbering and the correct pins were low, this means that the problem is on the display board.

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