(Topic ID: 287786)

System 11 A/C relay switching problem


By RobW

68 days ago

Topic Heartbeat


Topic Stats

  • 25 posts
  • 5 Pinsiders participating
  • Latest reply 52 days ago by GRUMPY
  • Topic is favorited by 2 Pinsiders

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#1 68 days ago

Hi all

Its a #Road kings. Having a problem with the left bottom kicker. Switch works fine during game but does not trigger the coil.
I'm thinking its the A/C relay?
I re-flowed solder on it , changed the diodes , traced all wiring .

-Coil does not work in test
-Coil works by grounding transistor

It did have a special coil locked on when i got it and a burned out a transistor and U45. I replaced them and all is good with that but, cant figure this one out. I cant seem to find where in the schematics this relay is.

Help!
Rob

#2 67 days ago
Quoted from RobW:

Hi all
Its a #Road kings. Having a problem with the left bottom kicker. Switch works fine during game but does not trigger the coil.
I'm thinking its the A/C relay?
I re-flowed solder on it , changed the diodes , traced all wiring .
-Coil does not work in test
-Coil works by grounding transistor
It did have a special coil locked on when i got it and a burned out a transistor and U45. I replaced them and all is good with that but, cant figure this one out. I cant seem to find where in the schematics this relay is.
Help!
Rob

Test the driver transistor first with a DMM. Grounding the transistor tab only tells you that the wiring from the output of the transistor is good, it does not test the driver transistor

#3 67 days ago
Quoted from wayout440:

Test the driver transistor first with a DMM. Grounding the transistor tab only tells you that the wiring from the output of the transistor is good, it does not test the driver transistor

Hey Wayout

I tested and replaced the transistor, just to be sure.
Do you know where can I find the schematic for this?

#4 67 days ago
Quoted from RobW:

Do you know where can I find the schematic for this?

Schematic Pdf download link from Ipdb.org:
https://www.ipdb.org/files/1970/Williams_1986_Road_Kings_Manual.pdf

#5 67 days ago

frunch

I'm sorry, should have mentioned that I have this. I still dont see where this section is in these schematic. Im looking for transistor 23 and the path to it. Maybe I'm missing something

#6 67 days ago
Quoted from RobW:

I'm sorry, should have mentioned that I have this. I still dont see where this section is in these schematic. Im looking for transistor 23 and the path to it. Maybe I'm missing something

That PDF is incomplete. In fact ... it's a stitching of two different manuals. The master AN board page (50) is from Road Kings. The CPU parts layout and sheet 1 of the schematics is from High Speed. It then skips sheet 2 of the schematic (the sheet you're looking for) and goes to sheet 3 from Road Kings.

Try downloading the High Speed manual. You can actually download any System 11 manual. The solenoid section of the schematic did not change during the System 11 life cycle.

#7 67 days ago

Haha, i just did the same thing as DumbAss suggested--here's Q23:

Screenshot_20210213_151906_com.google.android.apps.docs(1).jpg
#8 67 days ago
Quoted from DumbAss:

That PDF is incomplete. In fact ... it's a stitching of two different manuals. The master AN board page (50) is from Road Kings. The CPU parts layout and sheet 1 of the schematics is from High Speed. It then skips sheet 2 of the schematic (the sheet you're looking for) and goes to sheet 3 from Road Kings.
Try downloading the High Speed manual. You can actually download any System 11 manual. The solenoid section of the schematic did not change during the System 11 life cycle.

I still dont see the rest of this circuit. From the input, to the snubber relay.
Could this be a logic problem? I dont have a probe.

#9 67 days ago
Quoted from RobW:

-Coil does not work in test
-Coil works by grounding transistor

This is all you need to know right here. It's a CPU issue.

Quoted from RobW:

Could this be a logic problem? I dont have a probe.

Yes, you should buy one, it's a very inexpensive tool that can use the rest of your life.

#10 66 days ago
Quoted from RobW:

I still dont see the rest of this circuit. From the input, to the snubber relay.
Could this be a logic problem? I dont have a probe.

You don't really need a probe, you can use a voltmeter or DMM. You can see steady logic hi and low, and brief transisions. That's all you really need to troubleshoot the solenoid circuits.

#11 66 days ago
Quoted from wayout440:

You don't really need a probe, you can use a voltmeter or DMM. You can see steady logic hi and low, and brief transisions. That's all you really need to troubleshoot the solenoid circuits.

OK Wayout

Where do I start to track this down.

#12 66 days ago
Quoted from GRUMPY:

This is all you need to know right here. It's a CPU issue.

Yes, you should buy one, it's a very inexpensive tool that can use the rest of your life.

Thanks Grump, I will get one

#13 66 days ago
Quoted from RobW:

OK Wayout
Where do I start to track this down.

Check at the points indicated with a pulse symbol in the diagram when in switch test. You can use a voltmeter for this. A logic probe is nice but not necessary. I've been in professional electronics for 40 years and haven't needed one or owned one. My go-to is an oscilloscope for anything required beyond a DMM for pinball repair, even then bringing out a scope is very rare.

Forget about the AC relay. Unless you are having problems with a bunch of flashers and controlled solenoids, that's not your issue here.

Does the sling coil kick in either test mode or gameplay at all, or just when you ground the transistor tab?

Screenshot_20210214-171336 (resized).png
#14 66 days ago

Thanks again for your help!

It is the power kicker left outlane not the special solenoid if that makes a difference. Does not work during test only when grounded

#15 66 days ago
Quoted from RobW:

Thanks again for your help!
It is the power kicker left outlane not the special solenoid if that makes a difference. Does not work during test only when grounded

Ok. That is controlled solenoid #6, and is a different diagram (below). To divide and conquer, I would look at pin 11 of U19 for a positive pulse during test. You can use a logic probe, oscilloscope or a decent DMM/voltmeter.

Screenshot_20210215-045540 (resized).png
#16 65 days ago

Pin 11 of U19 is pulsing closed during the coil test.

#17 65 days ago

Now check for pulse activity at predriver Q19 emitter during test (which is the same point electronically as Q23 drivers base)

#18 65 days ago

No pulse at Q19 emitter but at the base. I can see the trace goes from U19 11, to Q19 base

#19 65 days ago

Test and or replace Q19. Note that it is common to replace predriver transistors automatically if driver transistors are blown. There isn't a whole lot else between where your pulse is and the driver. A couple of pull-up resistors, that's about it, and you can check those too before replacing anything. You've basically got the problem cornered.

#20 65 days ago

I did replace the pre driver Q19 with a 2n222. I think these are ok to use? What am I looking for with these resistor packs?

#21 65 days ago

The difference between those transistors are negligible, as far as pinball is concerned. For the pullups you can just take measurements between a nmknown good controlled solenoid circuit and your failed circuits, because the controlled drive circuits are the same. You can take resistive measurements in ohms with the circuit power off and/or voltage measurements with the circuit energized.

1 week later
#22 52 days ago

Solved!

It was a bad 7408 chip at U19. Output 11 .Re-socket and replaced chip and VIOLA !

Grumpy knew it was a logic problem. Haha, thanks wayout440 and GRUMPY .

Fight the Road Kings

#23 52 days ago
Quoted from RobW:

Solved!
It was a bad 7408 chip at U19. Output 11 .Re-socket and replaced chip and VIOLA !
Grumpy knew it was a logic problem. Haha, thanks wayout440 and grumpy .
Fight the Road Kings

I thought you checked the pulse at U19 in a previous post. Glad you got it working.

#24 52 days ago
Quoted from wayout440:

I thought you checked the pulse at U19 in a previous post. Glad you got it working.

Yea, pin 11 U19 was flashing closed during the coil test but it was normally closed with during normal play and with no power.

#25 52 days ago
Quoted from RobW:

Solved!

It was a bad 7408 chip at U19.

Glad you got it fixed!

Playball!

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