(Topic ID: 301087)

need advice: different behavior in lamp test mode vs attract mode

By EvanDickson

22 days ago



Topic Stats

  • 10 posts
  • 5 Pinsiders participating
  • Latest reply 22 days ago by slochar
  • Topic is favorited by 1 Pinsider

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#1 22 days ago

I'm purging the demons from a Skateball. Lots of lamps out on this one (bulbs are ok). I've replaced some SCR that tested as bad on the lamp board, and repinned J1, J2, & J4. Still a dozen or so lamps out and they stay that way when I swap lamp board with Flash Gordon, so I expect bad sockets for most(will try jumpering to a test socket shortly). But...

I have a couple lamps that work in attract mode and not in lamp test mode. What's up with that? Are test modes sometimes unreliable? Are lamps also controlled by something on the MPU? Bad chip? I don't know what to make of this.

Thanks!

#2 22 days ago

I have seen this but don't have a real explanation. My theory is bleed through when everything is energized.

An easy way to test the socket is this: use a jumper wire from the tab on a questionable socket to the tab of a working socket. If the bulb lights the socket is good. You can do this in attract to eliminate the previous issue.

I usually take the manual page and circle the problem lamps (once I've eliminated bad sockets) so I can see if there is any commonality between them i.e. same decoder ic, same connector.

When you repinned did that include replacing or reflowing the header pins? Those break alot due to the downward force of the harness.

#3 22 days ago
Quoted from Cheddar:

I have seen this but don't have a real explanation. My theory is bleed through when everything is energized.
An easy way to test the socket is this: use a jumper wire from the tab on a questionable socket to the tab of a working socket. If the bulb lights the socket is good. You can do this in attract to eliminate the previous issue.
I usually take the manual page and circle the problem lamps (once I've eliminated bad sockets) so I can see if there is any commonality between them i.e. same decoder ic, same connector.
When you repinned did that include replacing or reflowing the header pins? Those break alot due to the downward force of the harness.

I also reflowed all the headers on the lamp board. I'll do what you say - once I've replaced all the sockets that test as dead, then I'll look for commonality in what's left. Maybe there's an IC that needs replacing as well, or some common component. Thanks!

#4 22 days ago
Quoted from EvanDickson:

I also reflowed all the headers on the lamp board. I'll do what you say - once I've replaced all the sockets that test as dead, then I'll look for commonality in what's left. Maybe there's an IC that needs replacing as well, or some common component. Thanks!

Good plan, I have never replaced one of those ics though the scrs seem to blow first and protect them

#5 22 days ago
Quoted from EvanDickson:

I'm purging the demons from a Skateball. Still a dozen or so lamps out and they stay that way when I swap lamp board with Flash Gordon, so I expect bad sockets for most(will try jumpering to a test socket shortly). But...
I have a couple lamps that work in attract mode and not in lamp test mode. What's up with that? Are test modes sometimes unreliable? Are lamps also controlled by something on the MPU? Bad chip? I don't know what to make of this.
Thanks!

The MPU tells the lamp board to flash all the lamps in test mode, just like it controls them the rest of the time. So some of the lamps work during play and attract, but not during test, right? All lamps should flash in test but sometimes there is a lamp or two that might be left out of attract, but you've got the opposite issue.

#6 22 days ago
Quoted from frenchmarky:

The MPU tells the lamp board to flash all the lamps in test mode, just like it controls them the rest of the time. So some of the lamps work during play and attract, but not during test, right? All lamps should flash in test but sometimes there is a lamp or two that might be left out of attract, but you've got the opposite issue.

Correct, I've got a couple that show up in attract, but not in test. Which I find confusing and wonder if that points to a problem that I should deal with. Or if it's just "one of those things" to shrug at and ignore.

#7 22 days ago

Are the ones not flashing in test ones you've already repaired the SCR for? Sometimes I have SCRs that test fine but still do weird stuff like this

#8 22 days ago
Quoted from zacaj:

Are the ones not flashing in test ones you've already repaired the SCR for? Sometimes I have SCRs that test fine but still do weird stuff like this

Nope. Different ones. Maybe it's just a mystery of how the current spreads out across the circuit in test mode. I doubt this will be solved.

#9 22 days ago

Try replacing a few, can't hurt. Sometimes that solves it for me. Other times I ignore it since everything seems to work in-game

#10 22 days ago

http://www.pinballrebel.com/pinball/cards/Tech_Charts/Bally_Skateball_Tech_Chart.pdf

Look at the tech chart to the lamps that are having issues and see if they're all on the same 4514.

https://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Controlled_Lamp_Problems has the U-1-4 assignments as well.

All the lamp test does is turn all of the lamps on and off and all 15 nibbles are sent one after the other to the lamp driver boards' latches, regardless of if they're on or off. It always takes the same amount of time regardless of if 1/2 are on, 1/4 are on, all are on, off, etc.

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