Hesston, KS
Checked U-52 pin 11 and didn't get any signal at all. I put in a ic socket and ordered some 7408s. I reflowed solder to R-83 as they didn't look to be that good. I'll update after I get the 7408s in the mail and installed.
(Topic ID: 224305)
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4 weeks later
PinballManiac40 - I did install the new 7408 and that didn't solve the issue. I have put this machine on hold for awhile but want to get it all working again. I was able to eliminate the possibility of it being anything under the playfield as I did the test GRUMPY suggested and I was having the issues at the board with the connector off.
I've also noticed that if I leave the machine on for over an hour or so, sometimes it will reset the game in the middle of the game.
I'm not sure which components to test at this point or how to test them correctly.
Quoted from jag8511:hour or so, sometimes it will reset the game in the middle of the game.
I suspect the 5volts or 12v is low. Have all the capacitors been changed on the power supply?
Quoted from PinballManiac40:I suspect the 5volts or 12v is low. Have all the capacitors been changed on the power supply?
They have not been replaced. I'll check the voltage and post the results. Does voltage dip on system 11s?
If the smaller capacitors are drying out, they could be leaking and damaging the pads/traces under the cap(s). If the board looks wet around the smaller capacitors, that is what is happening already. Just tilt the capacitors to the side a bit to peak under them if they are not completely flush to the board.
Quoted from jag8511:I did install the new 7408 and that didn't solve the issue.
Remove the 7408 IC out of the IC socket. Then use your ohmmeter to test all the adjacent pins (pin 1 to 2, 2 to 3, etc...) to make sure none are shorted to the next pin of the IC socket. If so, you had too much solder flow up the legs and then shorted between the pins.
Quoted from PinballManiac40:Remove the 7408 IC out of the IC socket. Then use your ohmmeter to test all the adjacent pins (pin 1 to 2, 2 to 3, etc...) to make sure none are shorted to the next pin of the IC socket.
I took out the 7408 and tested. Nothing was shorting against each other. I did notice that it seams R83 has been getting hotter than the other ones around it.
Not sure if that helps possibly narrow down what it could be.
1ABB3610-4235-405F-BAD1-0F2A3223C5E8 (resized).jpeg83813E16-66C3-4180-979C-C01A67B2C544 (resized).jpegQuoted from jag8511:I did install the new 7408 and that didn't solve the issue.
Did you get pulses on pin 11 of U-52 in attract mode? You can compare with pin 6 of U-52. If not then cut the middle lead of Q-53 and recheck for pulses on pin 11 of U-52.
pasted_image (resized).pngQuoted from GRUMPY:Did you get pulses on pin 11 of U-52 in attract mode? You can compare with pin 6 of U-52. If not then cut the middle lead of Q-53 and recheck for pulses on pin 11 of U-52.[quoted image]
Here is a test of pins 1-14:
https://www.dropbox.com/s/0p2d2auxkpzbwbs/IMG_5110.MOV?dl=0
6 is low and pulsing.
11 is low but not pulsing.
I've not had a lot of experience using a logic probe. I assume this means to go ahead and cut the middle leg of Q53? Better to ask before I cut 
Since it is stuck low, either the resistor or the transistor is bad. Cut the base of the transistor to remove it from acting upon U-52. If it pulses then the transistor is bad, if not the resistor pack is bad.
Quoted from GRUMPY:Since it is stuck low, either the resistor or the transistor is bad. Cut the base of the transistor to remove it from acting upon U-52. If it pulses then the transistor is bad, if not the resistor pack is bad.
More often the case, but is it possible U52 has a bad data channel? Just asking for my own education.
Quoted from GRUMPY:Since it is stuck low, either the resistor or the transistor is bad. Cut the base of the transistor to remove it from acting upon U-52. If it pulses then the transistor is bad, if not the resistor pack is bad.
Cut the middle leg and test again? Or cut the whole transistor off and test again?
Quoted from robertmee:More often the case, but is it possible U52 has a bad data channel? Just asking for my own education.
Very likely, but you have to have hope that new parts are good. Even China makes some that work. 
After cutting off Q53 I get this with the probe:
https://www.dropbox.com/s/lyqmowb13ty3fh4/IMG_5112.MOV?dl=0
Pin 11 is now high/low and is pulsing but is pulsing different than pin 6
Quoted from jag8511:Pin 11 is now high/low and is pulsing but is pulsing different than pin 6
In attract mode the game is pulsing the lamps in different patterns so the outputs will be slightly different.
U-52 is working now. If its was me, I would replace both the predriver(Q-53) and the driver transistor(Q-54) as a pair.
Quoted from GRUMPY:I would replace both the predriver(Q-53) and the driver transistor(Q-54) as a pair.
I replaced both Q53 and Q54. That did not change anything. 
Pin 6 is low and pulsing but pin 11 is low and not pulsing like before
So this sounds as if the resistor pack SR-17 is working with no load, but stops working when there is a load. Or the new Q-53 is bad just as the old one was. You can test the resistor pack with an ohm meter. Check from pin 1 to 2, from pin 1 to 3 and so on. Pin 1 has a white dot for marking. Each of the 8 resistors in the pack should read 4.7k ohms. These don't go bad very often, but sometimes they fracture internally causing intermittent problems.
Quoted from GRUMPY:So this sounds as if the resistor pack SR-17 is working with no load, but stops working when there is a load. Or the new Q-53 is bad just as the old one was. You can test the resistor pack with an ohm meter. Check from pin 1 to 2, from pin 1 to 3 and so on. Pin 1 has a white dot for marking. Each of the 8 resistors in the pack should read 4.7k ohms. These don't go bad very often, but sometimes they fracture internally causing intermittent problems.
Was typing this when I saw new post. There was an older thread with similar symptoms and 2 pins of sr17 had shorted
Edit/Correction...It was SR16 that was shorted https://pinside.com/pinball/forum/topic/road-kings-lamp-matrix-problem
Quoted from robertmee:Edit/Correction...It was SR16 that was shorted
I have only seen this a couple times. Tested fine in circuit, looked fine too. Fell apart in pieces after removing the solder.
Quoted from jag8511:Pin 1-2 = 4.70
Pin 1-3 = 4.71
Pin 1-4 = 4.71
Pin 1-5 = 4.70
Pin 1-6 = 4.71
Pin 1-7 = 4.72
Pin 1-8 = 4.71
Pin 1-9 = 4.70
Pin 1-10 = 2.52
If you meter was showing a k behind these numbers then its testing fine. But it can still be bad.
You have changed 2 of the 3 parts that can cause this issue. Sometimes you just have to replace a part to be sure.
3 weeks later
Just got done replacing SR-17. Same issue still. No change.
I took a picture of the back and it looks like it’s starting to burn more on R83
PinballManiac40 Any ideas on what to try next?
AB9F17FE-3BF1-4493-81DD-991EB4AA6642 (resized).jpeg
Quoted from jag8511:it looks like it’s starting to burn more on R83
Someone could have replaced it, can't tell. Show the top side of the board in the area. Also what is the ohm measurement across the R83 and all the other 7? If all are within 1 ohm each, I say R83 is good.
Quoted from GRUMPY:Do an ohm test on SR-16.
Ditto....see post 221
Quoted from jag8511:I got the probe in the mail grumpy
After taking pictures and looking closer I noticed that diode is facing the other way from what the others are. So my wires are indeed wired wrong. Would that cause the transistors to smoke like that? Should I replace the transistors and try it again with the coil wired correctly? Or could this be a deeper issue?
I attached some pictures
[quoted image][quoted image][quoted image][quoted image]
I repaired electronic equipment for a living, seeing that green power board laying across the metal (re: conductive) speaker frame gives me the willies.
1 week later
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