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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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

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.

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

I dont have a logic probe.

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?

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

Sounds good. Thanks

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

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

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

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

Pin 6 is LOW.

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

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.

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

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

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?

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.

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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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

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

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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.

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

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

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.

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.