(Topic ID: 228755)

Data East CPU board - magic smoke release


By kcZ

6 months ago



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  • 50 posts
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  • Latest reply 6 months ago by wayout440
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#1 6 months ago

Playfield swap on my DE JP resulted in magic smoke from the CPU board. I'm pretty sure I have the playfield issue fixed but now I'm fixing the board. I replaced a couple bad transistors Q26/Q18 and Q43/Q35 the only components that still do not work are associated with the Q43/Q35 components. Poking around, I noticed the center leg of Q35 had continuity to ground. I pulled that transistor and the trace looks good but still continuity to ground. Could I have shorted out the resistor at RA10? It only shows ground to the pin associated with Q35, all other pins seem fine. I'm likely going to pull that resistor network and check the pin continuity to ground when I get home tonight unless there are any better ideas.

#2 6 months ago
Quoted from kcZ:

I'm likely going to pull that resistor network and check the pin continuity to ground when I get home tonight unless there are any better ideas.

I agree - that's what I would do.

#3 6 months ago

I pulled the resistor at RA10. I was still getting continuity to ground at the center pin location of Q35 as well as the corresponding pin location at RA10. I thought that maybe it was solder at the center pin of Q35 so I lightly cleaned the hole with a tiny drill bit (by hand). Now I no longer get continuity to ground at the Q35 nor the RA10 locations.

How the heck to I get a transistor back in the Q35 location without having my continuity to ground issue now?

#4 6 months ago

You want to avoid shorting to the same spot, so you could get a very small piece of heat shrink or strip a piece of insulation off a wire to create a small tube to wrap the leg of the transistor in. From there you could add a proper jumper wire on the reverse side of the board. Another way would be to bend the center leg out to avoid the hole altogether then running wrap wire around the transistor leg, through the hole and back to the resistor pack.

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1 week later
#5 6 months ago

So, I got some components in order to be able to replace what I thought would need to be replaced. The ground at center pin of Q35 was bothering me, I decided to pull the resistor array RA10. I still had ground at the center pin of Q35 as well as the corresponding resistor pin location.

I used my spare CPU board (DMD issue but everything else works) as a test case to compare. I started to poll around the traces and came to the conclusion that the source of the bad ground was the component 7408. I swapped this component with the spare and fixed my continuity to ground issue.

See pic below, red trace is what I figured was the source of the ground.

I am still having problems with my solenoids.... see other pic (highlighted coils do not work). Is there possible something further up the line that is causing me problems?
JP_DeadSol (resized).JPGJP_Ground (resized).JPG

#6 6 months ago
Quoted from kcZ:

came to the conclusion that the source of the bad ground was the component 7408. I swapped this component with the spare.

After you did this, you still measure a continuity/low resistance to ground where you shouldn't? Did you check to see that the short was cleared after you removed the 7408 but before installing the new replacement?

It's possible to have seemingly unrelated problems be related....but not always easy to come to this conclusion. I see nothing as an obvious single point of failure for these multiple problems from the info presented. In these cases I recommend focusing on one problem at a time. Then when it is solved, sometimes other problems that are related are revealed. If you are comparing measurements between your non-working channel and a working one and the measurements differ wildly, then that is clue to be followed.

#7 6 months ago

The continuity to ground has been fixed but I still have several coils that still don't work. I've been working at one at a time, the coils associated with Q43 (left scoop and some flashers) but I'm starting to wonder if they are party of a bigger problem.

#8 6 months ago

Double post

#9 6 months ago
Quoted from kcZ:

The continuity to ground has been fixed I've been working at one at a time, the coils associated with Q43 (left scoop and some flashers) but I'm starting to wonder if they are party of a bigger problem.

Did you check the downstream wiring by momentarily grounding Q43 tab to make sure the left scoop fires?

After that, get a DMM on the 7408 output pin and see if you get a pulse in test mode.

#10 6 months ago
Quoted from wayout440:

Did you check the downstream wiring by momentarily grounding Q43 tab to make sure the left scoop fires?

About this.... How does one do this? I tried and caused more damage but I likely did something wrong.

#11 6 months ago

from the tech guides at http://techniek.flipperwinkel.nl/desega/index2.htm#trans

Testing TIP122/102 Transistor and Down-Stream Wiring/Coil.
If the coil fires in the above test, there may be a transistor problem. Next test the TIP122/102 transistors. Only do this for the TIP122 or TIP102 transistors! Damage can occur if this test is done on other transistors (like TIP42 or TIP36). This test will test everything from the CPU board down to the coil itself. If the TIP122/102 and coil pass this test, and the coil still doesn't work in game play, the problem is more "up stream". All that is left is the 2N4401 pre-driver transistor, and the logic TTL chip that ultimately controls the whole process (a 7402 for the special coils or 7408 for the constant power solenoids), and the PIA 6821 chip.

Note the TIP36c transistors can be indirectly tested using this method too, BUT the TIP122 pre-driver must be grounded. All TIP36c transistors use a TIP122/TIP102 as a pre-driver. If the metal tab on the pre-drive TIP122/TIP102 is grounded, this will activate the TIP36c, which will energize it's associated coil.

Game is on, and in diagnostic mode (push the green coin door button down, and press the black button on games Frankenstein and before to go into diagnostics mode).
Remove the backglass.
On games WWF Royal Rumble and later, close the coin door.
Find the transistor that controls the coil and/or flasher in question (refer to the manual).
Attach an alligator clip to the grounding strap in the bottom of the backbox.
Momentarily touch the other lead of the alligator clip to the metal tab on the TIP122/102 transistor (only works on these, may damage other transistors).
The coil or flasher should activate.
If the coil or flasher does not fire, it may be a transistor that is multiplexed through the L/R relay.
To energize the L/R relay (which will fire the other coil/flasher that is multiplexed), attach another alligator clip to the grounding strap in the backbox. Connect the other end of the alligator clip to the metal tab of transistor Q29. This will energize the L/R relay on the PPB or MRB board.
If the coil or flasher does not fire, and the coil or flasher did fire in the previous test, there probably is a wiring problem. A broken wire or bad connection at the connector plug would be most common. It is also possible a driver or pre-driver transistor is bad. Use the DMM meter to test the transistors on the board (see Transistors Testing Procedures for details).

#12 6 months ago

All coils fire (at least the L side) in this test. Since most coils fire both L & R, I assume there is not an issue with the L/R relay.

#13 6 months ago

Since it has not been presented earlier, I have to ask the question: Absolutely no signs of former battery corrosion on the MPU board?

Some housework. Check all coil mounted diodes. Check all driving transistors. The point is to make certain the diode protection is in place, because if you don't do this you run the potential of tracing your tail putting new parts in such as the driver transistors and having them get killed immediately. Once you know the downstream wiring, coil protection, and driving transistors are good, then you are left with working upstream into the logic circuitry.

#14 6 months ago

No battery corrosion on the MPU board. Coil mounted diodes... I think are fine but the only way of knowing for sure would be to clip them, most of them were replaced during the playfield swap. I was able to fire all coils by grounding their specific transistor, even the particular ones that I cannot fire in diagnostic tests (except for the dino mouth coil but that could be other issues).

#15 6 months ago
Quoted from kcZ:

No battery corrosion on the MPU board. Coil mounted diodes... I think are fine but the only way of knowing for sure would be to clip them, most of them were replaced during the playfield swap. I was able to fire all coils by grounding their specific transistor, even the particular ones that I cannot fire in diagnostic tests (except for the dino mouth coil but that could be other issues).

Ok. Then the driving transistors are confirmed good and the downstream wires and coils are confirmed as good. The focus of your troubleshooting forward will be on the logic section.

#16 6 months ago

Any tips on that?

#17 6 months ago

Try reading through http://techniek.flipperwinkel.nl/desega/index2.htm#trans particularly the section titled "I've Done the Above Tests & they Work, but the Coil still doesn't work in Game mode."

#18 6 months ago

I would go to the 7408 and gates before the coil drives and compare the signals at the inputs and outputs between a known good coil drive circuit and the bad one. You can use a logic probe, oscilloscope, or DMM to do this. Most of the time I just use a DMM set to DC volts. Put the game is test mode, and jot down the results while probing the signals, noting the states of the inputs and outputs at rest and look for the changes or spikes of a pulse to determine logic highs and lows. Once I know what is going on there, I could find out which direction th head next.

bin3 (resized).pngimages (resized).pngindex (resized).png
#19 6 months ago
Quoted from wayout440:

I would go to the 7408 and gates before the coil drives and compare the signals at the inputs and outputs between a known good coil drive circuit and the bad one. You can use a logic probe, oscilloscope, or DMM to do this. Most of the time I just use a DMM set to DC volts. Put the game is test mode, and jot down the results while probing the signals, noting the states of the inputs and outputs at rest and look for the changes or spikes of a pulse to determine logic highs and lows. Once I know what is going on there, I could find out which direction th head next.
[quoted image][quoted image][quoted image]

Question on the E-585-29 -SCR's How do you test the gate while the board is in the machine, or do you just look for the pulse on the IC as you describe above?

#20 6 months ago
Quoted from Craigb:

Question on the E-585-29 -SCR's How do you test the gate while the board is in the machine, or do you just look for the pulse on the IC as you describe above?

Just look for the pulses. Put in coil test, set your probes up to monitor a pin on a known good solenoid channel so you know what you are looking for, then move the probe to an equivalent pin on a defective channel to see what happens there when the MPU calls for that solenoid to be activated.

#21 6 months ago
Quoted from wayout440:

Just look for the pulses. Put in coil test, set your probes up to monitor a pin on a known good solenoid channel so you know what you are looking for, then move the probe to an equivalent pin on a defective channel to see what happens there when the MPU calls for that solenoid to be activated.

Don't have a probe yet, but on the list, upgrading to a soldering station and a few other thing, first.

So the if you are getting pulse and shorting the SCR make the coil or lamp work you replace the SCR? If no pulse to one SCR then probably the IC or the trace?

#22 6 months ago

TTL logic is cheap enough now... that if I've validated all works from the driver transistor to the coils... then I'd just shotgun the remaining TTL logic and replace them all. $0.75 - $3 for the peace of mind of not having to worry about the state of the logic.
Of course; I wouldn't do this for an unobtainum chip... just the common stuff like 74xx and 40xx series logic. Just my $0.02.

having said that: If your looking for some troubleshooting fun; by all means go for it.

#23 6 months ago
Quoted from Craigb:

Don't have a probe yet, but on the list, upgrading to a soldering station and a few other thing, first.
So the if you are getting pulse and shorting the SCR make the coil or lamp work you replace the SCR? If no pulse to one SCR then probably the IC or the trace?

Your voltmeter or digital multimeter doesn't have probes?....I don't understand.

SCR.s are for lamp circuits and transistors are for coil circuits. Fundamentally they are both used as switches in pinball, but the circuits have differences.

But you do understand the concept of divide and conquer troubleshhoting. If you are testing a device between the logic section and the drive circuit and the signal is not present, we look upstream into the "higher" logic. If the signals we desire are present, then we look downstream to examine the drive circuit.

#24 6 months ago
Quoted from Zitt:

TTL logic is cheap enough now... that if I've validated all works from the driver transistor to the coils... then I'd just shotgun the remaining TTL logic and replace them all. $0.75 - $3 for the peace of mind of not having to worry about the state of the logic.
Of course; I wouldn't do this for an unobtainum chip... just the common stuff like 74xx and 40xx series logic. Just my $0.02.
having said that: If your looking for some troubleshooting fun; by all means go for it.

I would do this if I had any on hand or had a local supplier to get them asap. I do plan on ordering from GPE as soon as their website is back up.. in the meantime, it is test and if needed replace with components from the spare board

#25 6 months ago
Quoted from Zitt:

TTL logic is cheap enough now...

The part is cheap enough, true. It's just a waste of time to replace a part that isn't the problem.
Shotgun is pretty much a last resort method. I'd rather take a few minutes with a meter to find what is actually broken.

#26 6 months ago
Quoted from kcZ:

I would do this if I had any on hand or had a local supplier to get them asap. I do plan on ordering from GPE as soon as their website is back up.. in the meantime, it is test and if needed replace with components from the spare board

What chips do you need? I have a wide variety, most likely have what you are looking for.

#27 6 months ago

I'm thinking the 74LS273 may be next. I checked the pins on the 7408 chips, things seem mostly the same. I checked these while in Diagnostic Mode, flasher test. As the game would cycle the flashers, I would see the voltage on the pins jump. 3.5V on the same pins 7408 to 7408.

Tim, you have a 74LS273 chip?

#28 6 months ago
Quoted from kcZ:

I'm thinking the 74LS273 may be next. I checked the pins on the 7408 chips, things seem mostly the same. I checked these while in Diagnostic Mode, flasher test. As the game would cycle the flashers, I would see the voltage on the pins jump. 3.5V on the same pins 7408 to 7408.
Tim, you have a 74LS273 chip?

I used to have a bunch... i was doing a lot of board work for people for awhile. Let me check my stash tomorrow and get back to you.

#29 6 months ago
Quoted from wayout440:

Your voltmeter or digital multimeter doesn't have probes?....I don't understand.
SCR.s are for lamp circuits and transistors are for coil circuits. Fundamentally they are both used as switches in pinball, but the circuits have differences.
But you do understand the concept of divide and conquer troubleshhoting. If you are testing a device between the logic section and the drive circuit and the signal is not present, we look upstream into the "higher" logic. If the signals we desire are present, then we look downstream to examine the drive circuit.

I was talking about a logic probe. Yea, I understand trouble shooting, I did it on large data backbone network for 30 years, kinda the same thing just larger. Segment from last known good point and work one section back at a time and yes, you should go to the down stream side of the IC and see what you have there.

#30 6 months ago

It looks like solenoids 1-8 are driven by the 74LS273 but solenoids 9-16 are driven by the 6821. You didn't mention which specific solenoids do and do not work in diagnostic test. Note the switched solenoids are driven by several different 6821s.

If you replace the 74LS273 but the failing solenoids are in the 9-16 range then that won't fix them.

#31 6 months ago

Coils 4L & 4R (left scoop and some flashers) are the ones I'm trying to resolve, they fire if I ground the transistor but won't fire in diagnostic mode. I have replaced everything on that coils path from the 2 transistors, the resistor array and the 7408.

#32 6 months ago

Based on that I agree. I would replace the 74LS273.

#33 6 months ago

GPE site is down... supposed to be back up soon. Grrrr

#34 6 months ago
Quoted from Craigb:

I was talking about a logic probe..

I've never owned a logic probe. We don't even use them at work (30+ years career digital electronics) You don't need a logic probe. You can do 90 percent or so of the logic troubleshooting with good digital multimeter.

#35 6 months ago
Quoted from kcZ:

I'm thinking the 74LS273 may be next. I checked the pins on the 7408 chips, things seem mostly the same. I checked these while in Diagnostic Mode, flasher test. As the game would cycle the flashers, I would see the voltage on the pins jump. 3.5V on the same pins 7408 to 7408.
Tim, you have a 74LS273 chip?

If you have also verified the gates of the 7408 pins are behaving the same....why would you replace the 74LS273? ...signals can't jump over a bad 74LS273 and become correct at the 7408. You have replaced the 7408 and verified the pins are behaving the same, the problem must be downstream from there.

#36 6 months ago
Quoted from wayout440:

If you have also verified the gates of the 7408 pins are behaving the same....why would you replace the 74LS273? ...signals can't jump over a bad 74LS273 and become correct at the 7408. You have replaced the 7408 and verified the pins are behaving the same, the problem must be downstream from there.

LOL..... Sure, use logic.

#37 6 months ago
Quoted from wayout440:

If you have also verified the gates of the 7408 pins are behaving the same....why would you replace the 74LS273? ...signals can't jump over a bad 74LS273 and become correct at the 7408. You have replaced the 7408 and verified the pins are behaving the same, the problem must be downstream from there.

Are you suggesting that I look at the components between the TIP102 transistor and the 74LS273 chip?

Looking at the schematics, I may have missed checking the RA26 resistor array as well as R76. The transistor at Q35 had been replaced.

#38 6 months ago

I'm confused now... After looking over the schematic for a bit.

I've been concentrating on the Q43/Q35 components... Says SOL. DRV 4
This is the transistor Q43 that I ground and get the coil to fire.

What is SWITCHED SOL. DRV. 4 on the CN19 plug? Should I look at that?

#39 6 months ago
Quoted from wayout440:

I would go to the 7408 and gates before the coil drives and compare the signals at the inputs and outputs between a known good coil drive circuit and the bad one. You can use a logic probe, oscilloscope, or DMM to do this. Most of the time I just use a DMM set to DC volts. Put the game is test mode, and jot down the results while probing the signals, noting the states of the inputs and outputs at rest and look for the changes or spikes of a pulse to determine logic highs and lows. Once I know what is going on there, I could find out which direction th head next.
[quoted image][quoted image][quoted image]

One of my issues is I'm not really familiar with the IC chips, my electrical background is limited, one year of electronics in high school and an RCA NASA soldering and wiring class as a freshman, 43 years ago! Not really sure of the flow, So taking 11, 12 and 13, is the flow to the gate 11 and the output 12 and 13, or am I totally missing the principal?
pasted_image (resized).png

#40 6 months ago

I think it's the other way around--inputs are at 12+13, output is at 11. Wayout can set the record straight for sure though.

If I'm not mistaken, the blanking signal holds one input 'high' (pin 13) while the other input (pin 12) gets switched 'high' from another chip, leading to a 'high' output (pin 11) from the 7408...

#41 6 months ago
Quoted from frunch:

I think it's the other way around--inputs are at 12+13, output is at 11. Wayout can set the record straight for sure though.
If I'm not mistaken, the blanking signal holds one input 'high' (pin 13) while the other input (pin 12) gets switched 'high' from another chip, leading to a 'high' output (pin 11) from the 7408...

Ok, wasn't sure, thanks.

#42 6 months ago

looking at the diagrams again, I see what your saying, so this would be a AND gate?

#43 6 months ago
Quoted from frunch:

I think it's the other way around--inputs are at 12+13, output is at 11. Wayout can set the record straight for sure though.
If I'm not mistaken, the blanking signal holds one input 'high' (pin 13) while the other input (pin 12) gets switched 'high' from another chip, leading to a 'high' output (pin 11) from the 7408...

Yes, this is correct. The only condition that produces a high output at pin 11 is pin 12 and 13 high. See the truth table I posted earlier.

#44 6 months ago
Quoted from kcZ:

I'm confused now... After looking over the schematic for a bit.
I've been concentrating on the Q43/Q35 components... Says SOL. DRV 4
This is the transistor Q43 that I ground and get the coil to fire.
What is SWITCHED SOL. DRV. 4 on the CN19 plug? Should I look at that?

Switched solenoid 4 is for the center thumper bumper. It would help if I could find a solenoid table....like Williams games put in their manuaks. Switched solenoid are essentially the same as Williams special solenoids. Constant power is available to the pops, slings and some kickers that require faster response than running through CPU logic.

#45 6 months ago
Quoted from kcZ:

Are you suggesting that I look at the components between the TIP102 transistor and the 74LS273 chip?
Looking at the schematics, I may have missed checking the RA26 resistor array as well as R76. The transistor at Q35 had been replaced.

Actually, between the 7408 and the driver transistor. You already verified correct signals at the 7408....no?..or at least that is what I interpreted in your post.

#46 6 months ago
Quoted from wayout440:

Actually, between the 7408 and the driver transistor. You already verified correct signals at the 7408....no?..or at least that is what I interpreted in your post.

I'm going to double check 7408 again tonight but I'm thinking it is good. So that means something between the 7408 to Q43 is bad. I did end up replacing everything in that string except those resistors (RA26 and R78).

#47 6 months ago
Quoted from ralphwiggum:

I used to have a bunch... i was doing a lot of board work for people for awhile. Let me check my stash tomorrow and get back to you.

Just checked my parts.. i have 138,164, 244, 373,374.... sorry man.

#48 6 months ago

Fixed. Replaced RA26 after measuring very high resistance from center pin of Q35 to ground. All the other transistors measured about 1k ohm but this one was up in the mega range.

#49 6 months ago

Congrats.... I find boardwork to be really relaxing and satisfying. Glad you were able to get through it.

#50 6 months ago

Good work!

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