(Topic ID: 243529)

Control Light Contact and Pin Cleaning Question


By pindude80

5 months ago



Topic Stats

  • 18 posts
  • 4 Pinsiders participating
  • Latest reply 5 months ago by pindude80
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#1 5 months ago

I recently bought a Harlem Globetrotters that turned out to be a little more a project than I thought it would be, isn't that the way it always goes though? Anyways, when I started to work on the control lights I had probably 15 or so lights that weren't / aren't working. I was able to wiggle the connectors and get some to come on but if I pulled the connector and put back on some of the lights wouldn't come back on without wiggling the connector again.

Yesterday I pulled the board and looked at the header pins. They all had some nasty looking black on them that I was able to get off with some fine sandpaper.

I know the best way to fix the lights would be to replace all of the header pins and and re-pin all of the connectors but I don't really have time for that now; if it were winter time I would but I'm behind on outdoor work. So my question is what it hurt to clean all of the headers pins with fine sandpaper like I did and also pull the wires out of the connectors and clean the contact surfaces of the contacts with fine sandpaper also? Is there any huge drawback to doing this?

#2 5 months ago

Not a good idea.

#3 5 months ago

At minimum, you should be reflowing solder on all the header pins on all the boards. Do that first. Next if you are still having issues with some insert lamps out, you have to do some troubleshooting. Is the bulb bad, is the socket bad, is the connection to the board bad, is the SCR bad, is the socket getting voltage etc etc.

Tbh, it is easier to replace the contacts and install new header pins than to clean them with sandpaper. It all takes time, but at least you'll know it was done right. I've worked on a few games now where I would have smashed the PO on the head with my ratchet if I saw them doing the halfassed things I've had to rework. Take your time and do it right.

#4 5 months ago

I did reflow the solder last night when I cleaned the pins but that didn't make a difference which was kind of surprising because some looked very questionable. I've checked and replaced bulbs on lights that are out so good there. The reason I was leaning towards connectors and starting there is because if I wiggled or took off the connectors and put them back on some lights would come on and the black coating of crap on the surface of the pins.

I am usually one to usually do things the correct way so you probably are right and maybe I can make some time to replace the pins and contacts this weekend. Out of curiosity though, and for my knowledge, why would it be bad to clean the contacts with sandpaper if it's a clean metal on metal contact?

#5 5 months ago
Quoted from pindude80:

why would it be bad to clean the contacts with sandpaper if it's a clean metal on metal contact?

You ever noticed how brass doesn't stay shiny very long? When you remove the tin plating on the pins, the brass will oxidize more quickly. If you have to for the short term, use one of those small brass wire brushes which is less aggressive.

#6 5 months ago
Quoted from Quench:

You ever noticed how brass doesn't stay shiny very long? When you remove the tin plating on the pins, the brass will oxidize more quickly. If you have to for the short term, use one of those small brass wire brushes which is less aggressive.

Ok, that makes sense, thanks for the explanation! I didn't get any brass showing through on the pins when I cleaned them up but they definitely aren't as shiny as new pins.

#7 5 months ago
Quoted from pindude80:

I did reflow the solder last night when I cleaned the pins but that didn't make a difference which was kind of surprising because some looked very questionable. I've checked and replaced bulbs on lights that are out so good there. The reason I was leaning towards connectors and starting there is because if I wiggled or took off the connectors and put them back on some lights would come on and the black coating of crap on the surface of the pins.
I am usually one to usually do things the correct way so you probably are right and maybe I can make some time to replace the pins and contacts this weekend. Out of curiosity though, and for my knowledge, why would it be bad to clean the contacts with sandpaper if it's a clean metal on metal contact?

Definitely don't rush anything. For the short term, it might work, but you'll just be reworking it again in the future. Might as well do it right and have it last for 30 more years. If anything, for the next guy. For me, doing board work has been therapeutic, if anything. There's something satisfying about desoldering the old stuff, and soldering in the new stuff. It's very enjoyable for me. Plus you get the satisfaction of knowing that your work was done well and not slopped together only to be undone by the next guy who would have preferred that you didn't touch it in the first place. Trust me on this

#8 5 months ago

I just got a desoldering and solder station a couple weeks ago so I'm very new to board work and kind of slow but like you said it is kind of therapeutic and I enjoyed re-flowing the pins last evening. I have wanted one of these games for a while now; I've developed an obsession lately for 70s games with spinners, and I'm just excited to get this going plus it needs more work than I initially thought but I need to go back to my old mantra of "if a job is worth doing, it's worth doing right."

#9 5 months ago

I am happy to report that Wed night and yesterday on my vacation day. I replaced all of the header pins and all but 2 contacts for the lamp board; I ended up re-doing 102 contacts yesterday; it wouldn't have been this many but I had the MPU out and accidentally redid one of the 28-pin connectors for it but I'm not mad about this because it will make the game more reliable and now 2 out of 4 of the MPU connectors have been replaced, I will end up replacing all of the header pins on this board also. The only bad thing is I ran out of contacts 2 short from getting everyone done on the lamp board so I'll have to replenish my supply and circle back to these two wires.

My Pinball Life order came in yesterday so I have some sockets to swap in if that turns out to be a problem on the lights that aren't working.

#10 5 months ago

After the header pins and contact replacement I still have about 14 control lights out. I am wondering if I'm missing power somewhere. I.E. the 2 contacts in J4 that I didn't have new contacts for.

Is there only the one test point on the lamp board for 5v? In other words, is the lamp board all or nothing?

#11 5 months ago

I may have linked to this thread in another one of yours, but if I didn't I would start a list of lamps that are out and start troubleshooting each one. You may find that there is a combination of bad lamps (especially if they're incandescent), bad sockets, poor connections to sockets, and bad SCRs. Make a list and start knocking them out one by one.

https://pinside.com/pinball/forum/topic/paragon-controlled-lamps-only-some-dont-work

#12 5 months ago

Panda, you did post that link in my thread when I was working on the control lights for my trident. Thanks for posting again! I will be following the steps that quench outlined to get these control lights working on my Harlem Globetrotters.

I had a total of 14 lights out. I went through with the grounding method to the tab of each socket and figured out which ones had bad bulbs and which ones needed cleaned. Getting ready to replace a few sockets now.

One thing that really has me concerned is two of the lights that I was testing right before my u9 chip blew up last time made a humming sound again in the speaker just like it did last time before it blew up. I wonder if this could be a shorted socket? I'm not going to try the grounding method again until I hear back from you guys.

#13 5 months ago
Quoted from pindude80:

One thing that really has me concerned is two of the lights that I was testing right before my u9 chip blew up last time made a humming sound again in the speaker just like it did last time before it blew up. I wonder if this could be a shorted socket? I'm not going to try the grounding method again until I hear back from you guys.

With the machine OFF, set your multi-meter to low resistance mode.
Measure the resistance across a working control lamp socket - you will read in the vicinity of 3 ohms.
Then measure the resistance across those two suspect lamp sockets. If you read zero ohms there is a short in the socket/lamp. If they read the same as other working lamp sockets then you will need to trace back the wires on those two lamps back to the lamp driver board to see where they are connected in case someone's put the wires in the wrong location.

#14 5 months ago

There might have been 3 that were making that noise- 2k bonus, 4k bonus, 7k bonus. I didn't mess with them once I heard the buzz in the speaker. While I was replacing flaky and non-working lamp sockets I replaced those 3. I just tested the ohms on them and got the following: 2k bonus- 4.3ohm, 4k bonus- 4.0ohm, 7k bonus- 1.5ohm. I also tested a working light in that area that I didn't mess with, the 1k bonus light, it was 4.2ohm

After I installed the new sockets I put it in test mode and noticed that one of the lights that I installed a new socket on wasn't lighting up- the B in the upper saucer, so I grounded the tab and it came on but it didn't flash on and off like the others; it was really bright then would dim slightly, and kept doing this until I took the ground off. I then noticed that the top yellow inserts in front of the center spinners weren't on so I grounded one of the tabs and it turned on the other top yellow, but I think it might supposed to be like this because the tech chart doesn't have a separate listing for each spinner lane; just says spinners 1, 2, 3, 4, 5.

I'm not sure if these are related or not but I looked up which SCR was for each light I was having trouble with and found out the "B" in the top saucer is Q59, 2k bonus is Q29, 4k bonus is Q57 which I think is the SCR that instantly smoked when I put the lamp board out of my Trident in Harlem Globetrotters, 7k bonus is Q38. I'm not sure if that helps to find out if these are related or not.

#15 5 months ago

Are the 2k bonus, 4k bonus and 7k bonus lamps working in lamp test mode?

Quoted from pindude80:

7k bonus- 1.5ohm

Take the 7k lamp out and measure across the socket again. If it's still 1.5 ohms the socket has a short. If it's open circuit, install a new lamp and remeasure looking for approx 4 ohms.

BTW when you touch both meter leads together in resistance mode what reading do you get?

Quoted from pindude80:

I installed a new socket on wasn't lighting up- the B in the upper saucer, so I grounded the tab and it came on

So that lamp/socket are working you need to go upstream to the lamp driver board.

Quoted from pindude80:

found out the "B" in the top saucer is Q59

So ground the anode leg of SCR Q59 (look at the reference links below for SCR leg definitions). If the "B Saucer" lamp illuminates, connection from the SCR to the lamp is ok. If not you have a bad connection somewhere between the lamp board and the lamp.

The methodical approach is:
(1). Ground the tab at the lamp socket. This completes the ground power path to the lamp and bypasses the logic boards. If the lamp illuminates the lamp/socket are ok. If it doesn't illuminate, inspect the lamp/socket.

(2). If point (1) works, then go upstream to the lamp driver board. The anode leg of the associated SCR connects to the tab wire at the lamp socket, so grounding the anode SCR leg completes the ground power path to the lamp. If the respective lamp illuminates, you have good connection from the SCR to the tab wire at the lamp socket. If it doesn't illuminate, inspect the respective crimp terminal at the lamp driver board connector for that lamp and check its pin header soldering for cracks.

(3). Finally if point (2) works, then you can manually switch on the SCR to test the SCR functionality. Connect a jumper wire at TP3 on the lamp driver board. Connect the other end of the jumper wire to the "gate" leg of the SCR. This electronically switches the SCR on. If the lamp doesn't illuminate the SCR is faulty. If it does illuminate then there are other components on the lamp board to investigate, but they are rare failures.

Reference links to the SCR leg definitions:
https://pinside.com/pinball/forum/topic/stern-trident-feature-lights-quit-working#post-4980816
https://pinside.com/pinball/forum/topic/stern-trident-feature-lights-quit-working#post-4981037

#16 5 months ago

Thank you very much for taking the time to type all of this out and walk me through the testing procedure. The methodical approach is gold and I'm going to have to save that for future reference!

Here's what I came up with:

The 2k bonus, 4k bonus and 7k bonus lamps do not work in lamp test mode

I took the light out of 4k bonus and got no reading so I put a different bulb in and got 4.0ohm so I guess a crappy bulb was the culprit here. Touching both leads together displays 0.0ohm on the meter.

1.) this worked last night
2.) grounding the anode leg did turn the light on
3.) TP3 to the gate leg of Q59 did not turn on the light so I guess the SCR is faulty.

#17 5 months ago
Quoted from pindude80:

3.) TP3 to the gate leg of Q59 did not turn on the light so I guess the SCR is fault.

Yep pretty much.
Confirm the process by jumpering TP3 to the gate leg of another similar working SCR and that it's associated lamp illuminates.
Replace SCR Q59 when you are happy the process has proved Q59 is faulty.

#18 5 months ago
Quoted from Quench:

Yep pretty much.
Confirm the process by jumpering TP3 to the gate leg of another similar working SCR and that it's associated lamp illuminates.
Replace SCR Q59 when you are happy the process has proved Q59 is faulty.

yep, did that and the respective light lit. Please see my edited post above; I was trying to break each part of your reply up in quotes, reply to each, but I couldn't get it to work.

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