(Topic ID: 242968)

GTB Top Score — Score Reel Issue (Help)


By goldenboy232

5 days ago



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  • 24 posts
  • 5 Pinsiders participating
  • Latest reply 15 hours ago by Runbikeskilee
  • Topic is favorited by 1 Pinsider

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#1 5 days ago

*** See bottom of thread for latest issue. This first issue is now resolved. ***

The 1975 GTB Top Score restoration I've been working on since March (off and on) is almost done. I've done a full cabinet repaint, small playfield touchups, added all-new exterior cabinet hardware and legs, and have gone through all the mechanicals.

Last night, after putting the playfield back together, I fired it up for the first time since taking it apart a couple of months ago, and there are a few minor problems to sort out.

When I press the start button, the score motor starts and the Player One reels reset to zero. At that point -- according to the manual -- the player unit SHOULD step once and then the Player Two reels would reset. My player unit is not making that one step after the Player One reels reset.

If I manually step it once, then the Player Two reels reset and it starts a game correctly on Ball One. I can then play a game all the way through to Game Over correctly. So, I'm looking for some assistance in deciphering that part of the schematic that shows the Add Player Unit coil and why it's not taking that step after the Player One reels reset.

There are other more minor tweaks needed, but let's focus on this one first. I appreciate the wisdom and help as always!
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#2 5 days ago

Is the diagram you see the 4 reel reset switches that need to be closed to advance the player unit. put a jumper around them and see if that fixes the issue. if so figure out which of the 4 is not closed... (move the jumper down the chain)

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#3 5 days ago
Quoted from pinhead52:

Is the diagram you see the 4 reel reset switches that need to be closed to advance the player unit. put a jumper around them and see if that fixes the issue. if so figure out which of the 4 is not closed... (move the jumper down the chain)
[quoted image]

Ken where on the reels are the reset switches? I’m not familiar with that term.

If someone could post a picture of which switch on the reel is the reset switch and show me which tabs I should bridge using a jumper wire, I'd appreciate it. I just need to see it to understand what to do.

#4 4 days ago

The problem above seems to be now resolved. I have a new issue, also related to the score reels:

I cannot get the Player Two thousands reel to advance when the hundreds reel advances from 9 to 0.

I have adjusted the switches on the 100s reel and they seem to be correct when in the 9 position. I spent two hours adjusting (and re-adjusting!) them to no avail.

Could it be something else? I know the 1000s reel does work, as a 1000-point target activates it.

Any suggestions? Maybe something else normally can affect this besides the reel switches?

#5 4 days ago

Check your schematic and find the horizontally-oriented circuit that leads to the 1000-pt relay (likely the L relay?). It should include a normally open (NO) switch on the 100-pt relay (M relay?), along with a NO switch labelled 9th-position, 2nd hundreds. There may be another switch in the circuit that would need to be checked.

Then, if the 1000-pt relay is indeed pulling in when the 2nd-player hundreds reel advances from 9 to 0, there will be another NO switch on the thousand-point relay that needs to conduct to fire the "add 2nd thousands unit" solenoid (circuit found lower down on the schematic).

Keep in mind that the bane of EM troubleshooting is the switch that "appears" to be clean and closed, but still does not conduct electricity. I've run into that situation many times. Some folks use alligator clips and jumper wires to short circuit each switch to make sure that isn't happening.

#6 4 days ago

I recently had a Doodle Bug that was doing the same exact thing. Take a file and file the contacts on the hundreds 9th position blade switch until they are shiny. For me it wasn't a matter of improper switch gaps or adjustments, it was simply not making a electrical connection because of old dirt / gunk on the switch contacts.

#7 4 days ago

Thanks guys . I will check — I am 90% certain that the L Relay is not pulling in when the Player 2 100s unit goes from 9 to 0. And because it’s working fine on Player One, I think it’s safe to assume it’s not the switches on the L or the M relays, since both circuits would have those same switches in common. I think it has to be on the player two reel itself, correct? (The player unit itself is not involved in this circuit, I don’t think.)

So on the Player Two reel there are three switches a top (outer) switch, a middle switch (with two contacts) and a lower switch (with two contacts). The top and middle are closed at the 9 position (which I believe is correct). Which of those is the switch that sends the pulse to the 1000s Relay? I have tried junpwr clipping but am not sure I’m doing it right

#8 4 days ago

Can you paste in a snippet of a photo of the schematic for that circuit?

The wie colors designated on the schematic will help you isolate which switch(es) you need to address.

#9 4 days ago
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#10 4 days ago

Hi Runbikeskilee
here it is. Greetings Rolf

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#11 3 days ago

Also not sure physically which exact switches the “On Add 2nd Hundreds” and “9th Position 2nd Hundreds” switches are on that reel.

#12 3 days ago

Ok, I'm not sure exactly where Gottlieb positioned the switches on a 1975 machine production, but the 9th position switch for the 2nd-player hundreds reel will have a green & white wire going to one of the switch-blade tab ends. Hopefully, you can still make out the wire colors.

From the schematic, your machine also has another NO switch in series with the 9th position switch, on the add 2nd hundreds unit. That switch will also have a green & white wire to one of the switch-blade tabs. I don't own a 1975 multiplayer to reference, but that switch just might be in tandem with the EOS switch. Below is a photo from a 1973 multiplayer score reel. It is the switch to the right that is open until the plunger pulls in all the way.

Need to check both those switches (that is the 9th position 2nd hundreds switch and also the on add 2nd hundreds switch) to see if they are conducting. Also inspect the tab ends to make sure a wire has not come loose.

Lee
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#13 3 days ago
Quoted from Runbikeskilee:

Ok, I'm not sure exactly where Gottlieb positioned the switches on a 1975 machine production, but the 9th position switch for the 2nd-player hundreds reel will have a green & white wire going to one of the switch-blade tab ends. Hopefully, you can still make out the wire colors.
From the schematic, your machine also has another NO switch in series with the 9th position switch, on the add 2nd hundreds unit. That switch will also have a green & white wire to one of the switch-blade tabs. I don't own a 1975 multiplayer to reference, but that switch just might be in tandem with the EOS switch. Below is a photo from a 1973 multiplayer score reel. It is the switch to the right that is open until the plunger pulls in all the way.

Need to check both those switches (that is the 9th position 2nd hundreds switch and also the on add 2nd hundreds switch) to see if they are conducting. Also inspect the tab ends to make sure a wire has not come loose.
Lee
[quoted image]

Thanks! That was it! It wasn’t closing when the plunger pulled in. It now works — thank you! And thanks to Ken Head for also pointing this out via text! Appreciate you both.

OK onto the next issue as I finish troubleshooting this game: the “lights special target when lit“ feature seems to be lighting the special even when it’s not lit. I believe this is the part of the schematic I should be looking at (C Relay is the Target Special Relay), but I’m not sure how to diagnose.

Can anyone help me with that?
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#14 3 days ago

Ok I figured out the issue. There was another topic in this forum about that light burning too brightly and burning out. Mine was doing the same thing.

I have ordered some of the 757 28-volt bulbs and that will solve the problem.

#15 3 days ago
Quoted from goldenboy232:

Ok I figured out the issue. There was another topic in this forum about that light burning too brightly and burning out. Mine was doing the same thing.
I have ordered some of the 757 28-volt bulbs and that will solve the problem.

if its driven by a 150 ohm resistor you just need 44 lamp versus a 47

#16 2 days ago
Quoted from pinhead52:

if its driven by a 150 ohm resistor you just need 44 lamp versus a 47

Apparently it’s an 85 ohm resistor. The other guy who had the exact issue with the same game went with the 757s and reports good results.

#17 2 days ago

Are you saying that the rollover lamp present in the game was burned out?

Maybe I'm not thinking clearly this morning (more coffee needed ), but I can't see how a 757 lamp is going to work properly in that circuit

The selection of the 85 ohm resistor was intended to act as a voltage divider and result in approximately 5.6-5.8V across a #44 lamp. Over time, many people replaced #44 lamps with #47 lamps. Due to a higher (real portion of the) impedance in a #47 lamp, the voltage across that #47 would then be closer to 8V. As Ken implied, that is why the lamp appeared to burn brightly and fail faster (25% over spec voltage).

You could try and use a multi-meter to measure the resistance of the "85 ohm" resistor and verify it is close to spec, but a #44 bulb should work just fine.

#18 2 days ago

A little more:

Many of these EM games were designed at a time when nominal line voltage was considered to be 110-115V AC. I've measured the line voltage in my rec room wall sockets at slightly over 120V and the voltage out of the "24V" standard transformer tap at closer to 26V.

If I amend my voltage divider calculations accordingly, that places 6.1V across a #44 lamp and 8.6V across a #47 lamp.
8.6 V is surely enough to shorten the lamp life substantially.

#19 1 day ago

Even more: I finally looked up the specs on a #757 lamp. It is rated for 0.08A at 28V AC. That should result in reistive component of impedance of 350 ohms.

Assuming 26V out of the transformer along with that 85 ohm resistor, that voltage divider circuit results in about 21V across the #757. Going to be dim, but it should last a looooong time.

I suggest trying the #44 bulb first.

#20 1 day ago

It keeps burning out the 44s or 47s — burns way too bright and then the bulb goes out.

Going to try the 757s.

#21 1 day ago

Ok, sounds like the resistor may not be at spec. Could some prior owner have replaced the resistor with a different value, or maybe the resistor is damaged?

I am guessing that other folks who used 757s must have removed the resistor when they swapped in a different lamp.
If so, then the 28V lamp would be running off the 24-26V nominal voltage from the transformer tap, which should work reasonably well.

If you have a multimeter, you could verify the value of the resistor and also check the voltage out of the transformer tap.

#22 1 day ago
Quoted from Runbikeskilee:

Ok, sounds like the resistor may not be at spec. Could some prior owner have replaced the resistor with a different value, or maybe the resistor is damaged?
I am guessing that other folks who used 757s must have removed the resistor when they swapped in a different lamp.
If so, then the 28V lamp would be running off the 24-26V nominal voltage from the transformer tap, which should work reasonably well.
If you have a multimeter, you could verify the value of the resistor and also check the voltage out of the transformer tap.

Not sure. If you search “too bright” in this forum that thread (it was very recent) will come up and you can see what the other owner researched and decided. Some of this is above my pay-grade.

#23 18 hours ago

Hi Runbikeskilee and goldenboy232
I guess You are talking about this topic - and this post https://pinside.com/pinball/forum/topic/top-score-star-rollover-special-light-to-bright#post-4980026 ? (actually the whole topic is good). Greetings Rolf

#24 15 hours ago

Thanks Rolf. That looks like the one. I had missed that thread a short while ago as I was on travel.

I suspect something is wrong with the "85-ohm" resistor, but it is good that the OP now has the machine working properly for he and his friends to enjoy!

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