(Topic ID: 248899)

Changing Special on Duotron


By Knxwledge

10 months ago



Topic Stats

  • 38 posts
  • 8 Pinsiders participating
  • Latest reply 4 months ago by JudeRussell
  • Topic is favorited by 1 Pinsider

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15th Position Switch Fix (resized).jpg
Specials Problem (resized).jpg
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#1 10 months ago

How (or can) I change the special on a Duotron? I'm assuming it's a jones plug somewhere but a lot of the labels were blown off during cleaning with compressed air, and I can't find a scan of the manual anywhere online. It's currently on extra credit, but I have it set to work on free play and the extra credit it adds messes it up. I'd like it to be extra ball. TIA!

#2 10 months ago

What do you mean by extra credit?

And how does being on free play mess it up?

#4 9 months ago
Quoted from EMsInKC:

What do you mean by extra credit?
And how does being on free play mess it up?

By extra credit, I mean that when special is lit and I hit the appropriate target, the game awards me another credit (as if I put in another coin), and it advances the credit reel. I should have said free credit. It being on free play isn't the problem by itself. It becomes a problem when the game gives me a free credit and increments the credit reel. The way I've set up free play, I have 1 switch permanently closed when the credit reel is at 0 credits. The free credit(s) I get from the special messes this up.

Quoted from currieddog:

Radio plug in the back box.

The only radio plug/jones plug I see in the back is the points scoring one (approx. 10 rows and 2 columns), which doesn't have anything to do with special, if I'm not mistaken.

#5 9 months ago

Duotron is a replay machine by design. There is no way to convert a special award to an extra ball. Moreover, it does not even have an extra ball feature that could potentially be hacked for this purpose.

On most replay machines set to free play, you rely on the non-zero replay counter to give you the satisfaction of a game well played (and the score, of course). Is your replay counter not counting up as a result of a special hit? Or free play doesn't work when the credit counter is non-zero? If so, search the forum for setting free play…

https://pinside.com/pinball/forum/topic/setting-for-free-play

#6 9 months ago
Quoted from DaMoib:

Duotron is a replay machine by design. There is no way to convert a special award to an extra ball. Moreover, it does not even have an extra ball feature that could potentially be hacked for this purpose.

Oooop, that occurred to me later ...

#7 9 months ago
Quoted from Knxwledge:

By extra credit, I mean that when special is lit and I hit the appropriate target, the game awards me another credit (as if I put in another coin), and it advances the credit reel. I should have said free credit. It being on free play isn't the problem by itself. It becomes a problem when the game gives me a free credit and increments the credit reel. The way I've set up free play, I have 1 switch permanently closed when the credit reel is at 0 credits. The free credit(s) I get from the special messes this up.

The only radio plug/jones plug I see in the back is the points scoring one (approx. 10 rows and 2 columns), which doesn't have anything to do with special, if I'm not mistaken.

I'm still not seeing what in the world your issue is here.

On a credit unit there is a zero position switch that opens when the credit reel shows zero. That opens the circuit to the start button and doesn't allow you to hit that button to reset the game. There is also a max credit switch that is closed until the game reaches max credits. That opens the circuit to the credit unit step up coil and doesn't allow the game to add more credits.

When you set up a game for free play the zero position switch should be closed at all positions on the reel, not just zero. So you're saying that at 0 the switch is closed and you can reset via the start button, but you can't do that with the reel at any other position? That makes no sense because the switch in its normal state is closed at any other position than 0. I'm not sure how you mangled the switch to do that, or why you would do it in the first place.

You want to set that switch so it is permanently closed in all positions and you're done. You'll get credits for specials and you can still start the game even with no credits on it.

#8 9 months ago

Hi EMsInKC
I do not see a Maximum-Switch in the schematics --- here the Zero-Switch. Greetings Rolf

0Duotron-Work-05 (resized).jpg
#9 9 months ago
Quoted from rolf_martin_062:

Hi EMsInKC
I do not see a Maximum-Switch in the schematics --- here the Zero-Switch. Greetings Rolf[quoted image]

There is one. Every credit unit has one. You need to find the step up coil for the credit unit in the schematics and the max credit switch will be in that circuit.

#10 9 months ago

Hi EMsInKC
I do not have the Big Brave (1974-05) - I do not have the Duotron (1974-09) - but I have the schematics. "Out of Sight (1974-12)" I do not have - I have a partial schematics. Greetings Rolf

0Duotron-Work-06 (resized).jpg
#11 9 months ago
Quoted from rolf_martin_062:

Hi EMsInKC
I do not have the Big Brave (1974-05) - I do not have the Duotron (1974-09) - but I have the schematics. "Out of Sight (1974-12)" I do not have - I have a partial schematics. Greetings Rolf[quoted image]

15th position switch is what you're looking for. It's right there.

#12 9 months ago

Hi EMsInKC
in my schematics "Duotron" I do not see a "15th Pos. Switch". Therefore I am not 100% sure about wire colors and so feel uncomfortable talking about the switches on the Replay-Unit.
I also wonder about the OP's solution of "Free Credit / Free Play". Greetings Rolf

0Duotron-Work-07 (resized).jpg
#13 9 months ago

It's entirely possible it's a mistake on the schematic. There's no doubt it has one.

4 months later
#14 5 months ago

15th position switch is in line with the J Relay Coil (Add Replay Unit Relay)

Ignore the arrows; special was not working, and I found a bad connection or broken wire between the table (DX contact) and back-box (15th position contact / J contact), so I've got a jumper in there until I spend the time to isolate the problem. So I happened to have this image ready.

I'm poking around with my replay unit, it was set up for 10 replays max when I got it, and looks like the mechanical stuff / 15th position contact is a bit messed up / mangled, so poking around back there is one of my back burner projects.
Specials Problem (resized).jpg

#15 5 months ago

Hi JudeRussell
thanks for Your post-14 - someting new to me ... "J-Add-Replay-Unit-Relay" and THERE in the wiring is the "15th Pos (Replay Unit) switch". Greetings Rolf

#16 4 months ago

So now *I* am officially flummoxed by the 15th position relay / replay unit stepper on my Duotron.

Primary Symptom: the Replay Unit Stepper never stops, just keeps incrementing, past the stop (whether set for 10 or 15) until the little post mashes into the switches. No damage so far. I've checked the 15th pos switch - it opens properly (actually on the 14th position, needs a little adjustment)

The game decrements fine to zero (there seems to be a mechanical stop there). The game increments properly up through the max, via replay button, special, match, or point awards.

Looking at the schematic I uploaded two posts up the thread; the 15th Pos "Replay" unit N/C switch is in line with the Special Targets. And I've verified that this works - with the replay stepper at max, the contacts open, the special no longer works - the Relay J N/O contacts which lead to the Add "Relay" Unit coil remain open.

HOWEVER, I can continue to add games via the coin chute, points, and match. There seems to be nothing in line with the coil of the Add "Replay" Unit to disable these other paths.

Am I missing something?

Or....is this a wiring error, and I ought to rewire the N/C 15th Pos "Replay" unit to the coil of the Add "Replay" Unit (like in the Big Brave schematic above).

Time to get the soldering iron out. I'm normally loathe to mess with the original wiring but I cannot see how this is not a wiring error.

Edit: Rewire completed. Mischief managed, that resolved things. I'll post a marked up schematic in a bit. I'm just a little sad that the game is no longer "stock" (whatever that means). But glad this annoying little issue is off the punch list. Also glad I could find my soldering iron.

#17 4 months ago
15th Position Switch Fix (resized).jpg
#18 4 months ago

Your fix looks good... it looks like, on Duotron, they might have used logic more appropriate to the "half-moon" credit unit than the drum credit unit that you have. It seems like a design error, possibly Duotron was designed to use the half moon, but they switched back to the drum credit unit late in the design or in production? The half moon didn't appear until Super Soccer, 6 pin designs later.

My half moon pins (Abra and Spirit of 76) do not have the 15th Pos switch protecting the add replay function, my drum pins (Volley and Bank-A-Ball) do.

It would be interesting to see the logic in Magnotron and the pins between Duotron and Super Soccer (Far Out, Free Fall, Royal Pair, Out of Sight, and Atlantis) to see if any others have this issue. I don't have any of those schematics.

Whoa, Atlantis early production used half moon also, then switched back to drum later in the production run. It really sounds like that half moon credit unit was a problem (and if you ask around, you'll find people that say it still is). The half moon only lasted about 15 pin designs or so....

#19 4 months ago

Sorry, juderussell , there's a problem with your modification.

  1. If the Replay unit is on its maximum value of 15
  2. and the user hits the Left or Right Special target
  3. which will activate the J relay.
  4. The 15th Pos Replay unit switch will be open
  5. which will keep the Add Replay Unit solenoid from activating
  6. so the On Add Replay unit end-of-stroke switch (between 9H & 10I on the schematic) won't open.
  7. Then the J relay will stay locked on through its hold switch (at 9F on the schematic)
  8. which will burn it out.
#20 4 months ago

I suppose one could change the special by adding a relay that activates when Special is hit and which kills the 1st Ball relay until the ball drains so that when the ball is served up again it stays on the same player, sort of like a Shoot Again. I'm sure it would be more complicated than that though. Somebody out there probably tried it already. Would have to make it still work at the end of the last ball of the last player instead of going to game over, it's making my brain hurt just thinking about it.

#21 4 months ago

So, are we in agreement that this is a design error? All credit unit switches are accounted for and the schematic is accurate?

If it is a design error, these Duotrons (and, possibly Magnotrons) have been out there for 45 years or so mashing their credit unit switch stacks occasionally when someone coins up too much or a really good player beats it like a drum.

The question is - how far do you want to go to fix it vs how much of a problem it really is in your home environment...

#22 4 months ago

Looks like the above-mentioned scenario where they used the 'half moon' wiring design on this 'standard' credit unit game. My half moon Fast Draw doesn't use a "add replay unit relay" so apparently it just keeps pulsing the credits past the limit and it's no big deal? But then why did they specifically worry about the credit unit on Duotron being disabled at pos. 15 *only* for hitting a Special? How about this for a 'fix' - just reroute the 15th pos. switch wires so that they are in series with the add credit coil to always cut it out at pos. 15, and splice the previous two switch wires (for the J relay) together?

#23 4 months ago

Thanks everyone. Saved me some grief / burning out the J Relay....I disabled the specials for the short term until I come up with Plan B.

I'm not 100% convinced there is a design error, but I see no other provision to inhibit excessive credits via the coin slot, points awards, or matches (just through the special). I too find it somewhat incredible that, if this is an error, it's been out there 45 years. Anyone who can set me straight if I'm off in the wilderness, please chime in!

To help me understand the coils / relays better, I initially assumed there was no problem holding in the J relay coil (like the AX / BX / CX / DX coils, A-9740) - would it be OK to hold in the A-9735 J coil for the duration of the ball (assuming there was some way to clear it) or is this coil rated / intended for short-term / instantaneous duty only?

This is the fun part, right?

#24 4 months ago

Adding another pos 15 switch that directly opens the add credit coil would work.

#25 4 months ago
Quoted from frenchmarky:

Adding another pos 15 switch that directly opens the add credit coil would work.

That would work. Another possibility is removing a tooth from the Add Credit unit ratchet "gear" so the step up lever can't turn it past the 15th position.
If it isn't already that way from the factory.

#26 4 months ago

Working backwards scenario: They designed the game with the standard credit unit and pos. 15 switch (timeline-wise it makes sense) but then realized the J relay on Duotron (which I think functions sort of like a pop bumper relay to assure a Special is fully scored) needed to have a separate pos. 15 switch to prevent it from locking on... but normally those credit units don’t have any custom changes from game to game, correct? So they used the switch to handle J instead and said oh well so it will try to add more than 15 credits for scoring and coining, but not a huge deal for one title. Sounds totally plausible to me. And yes gears like that or say in a bonus counter would be limited in rotation by the number of teeth.

#27 4 months ago

Would this work for unlocking the J relay? Since the special targets are only enabled during motor 1C anyway (first part of a motor run cycle). Change makes it so J will always unlock with any motor run, but when it should score a special (motor is at rest) it will. But I don't have the entire schematics so gotta be a flaw in this somewhere. Your special lights do 'motor out', right? I.e. they cycle on and off with other 'when lit' items?
image-22 (resized).jpg

#28 4 months ago

Hi
if I would do something - I would do as frenchmarky suggested in post-24. Rather easy to do and can be taken away by an latter owner --- easy to document.
IF (if, if) I would like to try - does this works ? - I maybe would try "wiring I show in the JPG".

One thing that is never discussed - shouldn't be an switch on the Replay-Unit to open and stay-open Positions 10,11,12,13,14,15 to make the Coin-Lockout-Coil to quit pulling ?
The way it is wired in the pins : Replay-Counter (lets say) is in position-12, a coin is worth 5 replays - throwing-in a coin makes the Replay-Counter to step-up - BUT ONLY three steps (reaching position 15: No more credits added). Greetings Rolf
0Duotron-Work-08 (resized).jpg

#29 4 months ago

@JudeRussell - I’m looking at the credit unit (of a 76 Volley) in the 15 position. It doesn’t look like subsequent pulses of the add_replay relay would do any damage. The lower leaf of the opened “15th pos” switch is pinned between the 15th replay post mounted on the gear and a structural member on the switch stack, stopping any further rotation of the credit drum (see pic). Additional pulses result in relatively little movement or stresses on any component. Do you have that silver structural “leaf” in your switch stack?

IMG_1729 (resized).jpg
#30 4 months ago

Rolf: "shouldn't there be a switch on the Replay Unit to open and stay open Positions 10,11,12,13,14,15 to make the Coin-Lockout-Coil to quit pulling ?"

Answer: The pinball companies figured that anybody who'd drop another quarter into a 5-games-for-25-cents machine that already has 14 credits showing on it is either so stupid they deserve to lose it, too drunk to notice or has so much money to burn they don't give a damn.

#31 4 months ago
Quoted from DaMoib:

@JudeRussell - I’m looking at the credit unit (of a 76 Volley) in the 15 position. It doesn’t look like subsequent pulses of the add_replay relay would do any damage. [quoted image]

He said his switch needed adjusting and was actually opening at 14 so on this particular game with it doing the extra pulses after 15, the switch would start getting bashed.

#32 4 months ago
Quoted from DaMoib:

Do you have that silver structural “leaf” in your switch stack?[quoted image]

Not home at the moment; that component is there but looks to be something less than structural - bakelite or heavy cardstock or light fibreboard. I'll take a photo.

When I got the machine, the pin was at the 10 game setting, the credit unit had run past 15, and the pin had mashed up the limit switches, which is why the 15th position switch needed some attention, it was all bent and crushed.

I thought there might be some sort of a mechanical lock-out (like at the zero position) that was not working or needed some attention, initially.

I'm close to putting things back to "normal" whatever that is and just not running the credit reel up that high. I might need to set the award levels higher, because I hit 3x replays on points pretty regularly!

But just knowing that it's working as designed (and not something worn, broken, or misadjusted) means I can take it off my punch list of little projects.

#33 4 months ago

Oh crap I never thought of that, having the pin adjusted to less than 15 but the wheel keeps advancing. That switch *would* get crushed!

#34 4 months ago

There's a bakelite board in my Bank-A-Ball, looks like that was upgraded to metal in the post half-moon era.

You should definitely make the game harder if you're living in the 15 replay region. Up the award levels, higher pitch, conservative posts, take those toilet paper rolls out from underneath the front legs...

#35 4 months ago

Hi frenchmarky
(I do agree with You (post-30) - but) what do You say to these "my marked green in the JPG". Greetings Rolf

0Fireball-Work-07 (resized).jpg
#36 4 months ago
Quoted from DaMoib:

Do you have that silver structural “leaf” in your switch stack?[quoted image]

Here's what I have, a bakelite leaf instead of the silver metal. Much more bendy. Shown here run off the reel (15+) but yeah, hitting the Add Replay Relay does not seem to be messing things up too much. It was all bound up when I got it, so maybe someone really ran it up.

I undid all the "repairs" and back to original state. I upped the score award levels, and will just leave it be as is. Apologies for the fire drill.
IMG_7319 (resized).jpg

#38 4 months ago
Quoted from DaMoib:

You might also want to consider this tip:

So freaking helpful. Perfect really. THANK YOU!

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