Black Knight: quiet buzzing, then fuse blown

So I got my boards back today from barakandl - he did a FANTASTIC job restoring my MPU and driver boards. Highly recommended.

When I put everything back together, my right side flippers didn't work. I reseated all the cables and lo and behold they started working (as did everything else). So I fired up a game. Shortly into the game, I heard a buzzing inside, near the bottom flippers, triggered by nothing I could notice. This continued for about 15 seconds or so and now none of my solenoids are working. My fuse blew. What would you recommend I check before simply replacing and blowing another fuse, oh wise pinside members?

Thanks in advance.

#2 8 years ago

CDY

cody_chunn

Inactive member

You should have a few seconds before the fuse pops. What you want to do is power up for 2 SECONDS at a time, and try to catch a solenoid activating. Start with the outhole and release (shooter feed) solenoids. Open the coin door and get your eyeballs on one, power up, see if it fires, power down. Wait 5-10 seconds. Repeat these steps, checking on the slingshots, target banks, etc...until you find one activating.

Don't forget the magnets. Hold a ball over the magnet and power up for 2 seconds. If it grabs the ball, it's locked on.

Let us know what you discover.

#3 8 years ago

QB3

Razor

Inactive member

North Bay, ON

10y 26,400 247

Could be the 5 volt regulator on the power supply. My BK had a similar issue.

#4 8 years ago

JOE

tornado

Pinside+ Frequent

Ok thanks. I got some new fuses and found out it is the bumper that is locked on when I power it up. Any suggestions on how to fix?

Thanks!

#5 8 years ago

JOE

tornado

Pinside+ Frequent

Here are some pictures of the locked on jet bumper:

DSC01385.jpeg

DSC01386.jpeg

DSC01388.jpeg

DSC01389.jpeg

DSC01391.jpeg

#6 8 years ago

CDY

cody_chunn

Inactive member

I would replace the diode on the coil, noting polarity (which side the silver band is on) along with the driver and pre-driver transistors. Power up for 2 seconds and see if it still locks on.

#7 8 years ago

AMS

barakandl

All the special solenoids worked here, but shit happens. Check that electro cap on the pf switch. If it is shorted, it would lock the solenoid on I believe.

If the driver board transistor is damaged. Make sure the solenoid is wired up correctly with diode isolation and I will take care of it.

Thank you
Andrew

#8 8 years ago

JOE

tornado

Pinside+ Frequent

Pardon my ignorance but when you say the electro cap on the playfield switch, what do you mean? The part that the ball rolls over to trigger the jet bumper?

Second, do you know what transistor is the one I should check on the driver board? I have a transistor here I can replace it with, but not sure which one to check.

Thanks

#9 8 years ago

)(

Solder_Splash

Pinside member

Sagamore Hills, OH

12y 42,150 995 5

OP
Quoted from tornado:
Pardon my ignorance but when you say the electro cap on the playfield switch, what do you mean? The part that the ball rolls over to trigger the jet bumper?

This:
Screenshot_2015-09-12-20-32-52.jpg

#10 8 years ago

JOE

tornado

Pinside+ Frequent

Thanks. So that is the same thing as a diode?

#11 8 years ago

CDY

cody_chunn

Inactive member

Nope. Completely different.

#12 8 years ago

AMS

barakandl

Simplest thing you can do it clip one end of that electro cap loose and see if the solenoid still locks up. If it does the driver board is probably damaged. I don't think that cap serves a major purpose besides help keeping the switch closed.

If it was shorted, that cap would be locking up the special switch input. Which i am pretty sure I remember having happen to me more than once.

I am not sure exactly what driver transistor that is without looking at a manual. It will be 17 to 22. To do a quick and dirty test. special solenoid connector off. DMM on diode test. Red lead on ground. Black lead probe the 6 top most solenoid drivers transitor tabs (the six right above the flipper relay). They all should read about .4 to .6. If any read 0.00 the driver board has a problem.

#13 8 years ago

JOE

tornado

Pinside+ Frequent

So just to confirm I am cutting this wire (which is part of the electro cap) to see if it locks up correct?

Black_Knight__quiet_buzzing__then_fuse_blown_-_Pinside_com.png

#14 8 years ago

JHG

Barakawins1

Inactive member

Woodcliff Lake, NJ

9y 69,300 2,113 3

yes

#15 8 years ago

JOE

tornado

Pinside+ Frequent

OK So I cut the wire, and the solenoid no longer locks up so I presume that the driver board is not the issue here correct? Is the fix to replace the electro cap? If so can someone point me to where I can find that part number? I am googling on electro cap and not getting very far.

Second thing, I tried a test game (sans bumper) and it all seemed to be playing fine. About halfway through the game, the right flippers cut out. Any suggestions on what I should test to get those going again? The rest of the solenoids seem to work fine (other than the bumper of course.

Thanks.

#16 8 years ago

JOE

tornado

Pinside+ Frequent

Here:
https://www.greatplainselectronics.com/proddetail.asp?prod=CEA-22uF-50V-RMD

So I'm getting a little smarter here . I found out electro cap is electrolytic capacitor, and am on the hunt for the part. The numbers on the one I removed are T. I. 22 MFD, 16 VDC 8025 JW11 85 (degrees) C?

#17 8 years ago

)(

Solder_Splash

Pinside member

Sagamore Hills, OH

12y 42,150 995 5

#18 8 years ago

AMS

barakandl

OP
Quoted from tornado:
OK So I cut the wire, and the solenoid no longer locks up so I presume that the driver board is not the issue here correct? Is the fix to replace the electro cap? If so can someone point me to where I can find that part number? I am googling on electro cap and not getting very far.
Second thing, I tried a test game (sans bumper) and it all seemed to be playing fine. About halfway through the game, the right flippers cut out. Any suggestions on what I should test to get those going again? The rest of the solenoids seem to work fine (other than the bumper of course.
Thanks.

Nice! that means that cap is shorted. Install a new one. 22uF, 16vdc (or higher) and go from there. The Driver board is probably fine unless the driver got damaged from the solenoid locking up. Sometimes the switch input TTL chips are not a fan of being locked on and crap out.

ebay.com link: Nichicon 22uF 50V 105C Radial Electrolytic Capacitor 10 pack
Great Plains Electronics CEA-22uF-50V-RMD

For flippers start simple, cabinet button and end of stroke switch, measure voltage at the flipper coil. Then check the connector on the driver board.

#19 8 years ago

JOE

tornado

Pinside+ Frequent

http://www.radioshack.com/0-22uf-50v-10-pc-mount-capacitors/2721070.html

Fantastic!

Quoted from barakandl:
ebay.com link » Nichicon 22uf 50v 105c Radial Electrolytic Capacitor 10 Pack Great Plains Electronics CEA-22uF-50V-RMD

Will these work? I have a RadShack nearby (and I'm the impatient type)

#20 8 years ago

JOE

tornado

Pinside+ Frequent

Actually I found this one when I got there:
http://www.radioshack.com/22uf-35v-axial-lead-electrolytic-capacitor/2721014.html

I think this will work.

#21 8 years ago

AMS

barakandl

22.0uF not 0.22uF

http://www.radioshack.com/22uf-35v-axial-lead-electrolytic-capacitor/2721014.html
will work fine.

#22 8 years ago

JOE

tornado

Pinside+ Frequent

OK that's what I bought. I just soldered it on, and fired her up. The bumper is still not responsive. Does it look like I did it correctly? I used the same polarity direction as the other one (I think).
IMG_6812.JPG

#23 8 years ago

AMS

barakandl

OP
Quoted from tornado:
OK that's what I bought. I just soldered it on, and fired her up. The bumper is still not responsive. Does it look like I did it correctly? I used the same polarity direction as the other one (I think).
IMG_6812.JPG

Put the game in solenoid test and see if the CPU can fire that solenoid.

#24 8 years ago

JOE

tornado

Pinside+ Frequent

Quoted from barakandl:
Put the game in solenoid test and see if the CPU can fire that solenoid.

Just tested solenoids. It does not fire.

#25 8 years ago

AMS

barakandl

Ground the driver transistor tab for that solenoid, if it kicks then, the driver board will probably need serviced again. When the special solenoids lock on, it literally only takes a few seconds for the TTL chips to get damaged in the special solenoid circuit. That is probably what happened.

You can logic probe the signals as they pass through the 7408 / 7402. I would imagine you have an output in those chips that has burnt open.

#26 8 years ago

CDY

cody_chunn

Inactive member

Put a new diode on that coil just to be safe. Note polarity.

#27 8 years ago

JOE

tornado

Pinside+ Frequent

Quoted from barakandl:
Ground the driver transistor tab for that solenoid, if

I grounded it, and it fired. Is the TTL chip something you think I (a relative EE newbie) can service myself? If so do you know what I need to order? If not, I can send to you if you're up to servicing it. Let me know.

I do not have a logic probe - can you recommend a good (not too much $) one?

Quoted from cody_chunn:
Put a new diode on that coil just to be safe. Note polarity.

I can do that. Will report back.

#28 8 years ago

AMS

barakandl

The TIP102, 2n4401, 7408 and/or 7402 could be bad. With a logic probe you can watch the signal cascade through the chips to the main driver transistor.

Repair level would be able to diagnose and successfully replace components and/or chips. I would cover this under the warranty, no charge.

I recommend the Elenco LP-560 logic probe.

#29 8 years ago

AMS

barakandl

Oh wait. I think you installed that cap backwards when compared to your first picture. If it is installed backwards, throw it away and try a new one.

The rib on the cap indicates positive end. It looks reversed from picture to picture. Might be as simple as that.

Back in the 70s and early 80s caps could have the positive leg marked or the negative leg marked. Now a days, it is almost always the negative leg is marked on electro caps.

#30 8 years ago

JOE

tornado

Pinside+ Frequent

Quoted from barakandl:
Oh wait. I think you installed that cap backwards when compared to your first picture. If it is installed backwards, throw it away and try a new one.
The rib on the cap indicates positive end. It looks reversed from picture to picture. Might be as simple as that.

Surprisingly I had the foresight to grab two of those caps before I left RadioShack.

OK I flipped it around. Same results (no activity when hit).

IMG_6818.jpg

Elenco ordered!

#31 8 years ago

AMS

barakandl

Driver board has been repaired. The TIP-102 was not so happy about being locked on for a period of time, the collector was open. New TIP102 and that circuit fires a solenoid with a switch trigger and a computer trigger OK.

#32 8 years ago

JOE

tornado

Pinside+ Frequent

It works great! Thank you again!

#33 8 years ago

AMS

barakandl