(Topic ID: 225496)

Stern Electronics Club (1977-1984).


By Mitch

1 year ago



Topic Stats

  • 2,517 posts
  • 207 Pinsiders participating
  • Latest reply 4 days ago by Whridlsoncestood
  • Topic is favorited by 103 Pinsiders

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Topic index (key posts)

7 key posts have been marked in this topic

Post #227 Various gate tips. Posted by cottonm4 (1 year ago)

Post #269 Hi quality thoughts from Cotton about inlanes. Posted by cottonm4 (1 year ago)

Post #279 Playfield touch up tips. Posted by klr650 (1 year ago)

Post #309 Stern inserts suggestions. Posted by cottonm4 (1 year ago)

Post #310 Seawitch gate flap solution. Posted by frunch (1 year ago)

Post #1033 Bally drop targets on the classic stern, even mix and match. Posted by cottonm4 (9 months ago)

Post #1958 Star Gazer podcast episode link. Posted by DRDAVE (4 months ago)


Topic indices are generated from key posts and maintained by Pinside Editors. For more information, or to become an editor yourself read this post!

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#484 1 year ago
Quoted from frunch:

I'm curious how they handled the shooter lane ball flap/loop guide on Beatles. It looks like they may have just put a one-way gate there. In fact, it appears that a soft plunge would send the ball down that odd little passage above the right slingshot and into play.

there are a few games like that.... POTC? (stern)

2 months later
#825 11 months ago
Quoted from Whridlsoncestood:

Is that trace only populated if you tell him it’s for a game with speech? Or was that something in the last that has changed?

I fixed this missing trace around June 2018, all boards past version eight or so will have this track and will work with Stern Speech. If you are unsure look by the J4 plug. If there is a pin silk screened labeled LAMP INT then it is ready for Stern games with speech. If the silk screen print LAMP INT is not by J4 then a jumper will need to be made for Stern Speech games.

When I originally did the board I saw "LAMP INTERRUPT" on the mpu200 schematic and though "huh, no reason the lamp board interrupts the MPU so I can leave this out". That was a mistake and the lamp interrupt is what triggers the speech card to read the lamp address/data to play speech. Only effected the few Stern games with speech.

#831 11 months ago
Quoted from SR230CC:

Nice! They do have free play. I may have to get one.

All the MPU100 (and Bally)games have free play which you can turn on/off by a dip switch setting.

The MPU200 games have an alternate ROM that is always free play.

#836 11 months ago
Quoted from Whridlsoncestood:

barakandl Any chance of making SB-100 sound boards too? Always a pain.

Chances are good. Right now time to work on new projects is limited. I am hand assembling everything still and I can hardly keep up with what I am currently doing.

For the SB100 I finished the schematic about a year ago and did the board layout over 3-6 months back. It is a rough layout that needs tweaking for sure. Also pretty sure there is going to be some surprises and revisions needed. There was so many schematic errors in the original SB100 drawings I am not sure I have found them all.

For those taking notes... here at the errors on the SB100 schematic identified so far (some of these discovered by others and I thank them).

- Q1 emitter (top of C18) is connected to +5V VDD (schematic does not show any 5V connection)
- U6 Q output is pin 3, not pin 13 (the flip flop in the sound effect section)
- Pin 25 on the J1 connector (reset line) is not connected to anything (rev C-1)
- U19 (LM556) power pin is not connected to VCC, it's connected to +5V VDD (from the 78L05)
- R11 power is connected to +5V VDD
-inconsistent 5v labeling
-4013 U9A P6 "channel one set" not drawn anywhere. Probably gnd (yes?)
-U6 is connected to +VDD, not +VCC
-R3 and R7 are connected to +VDD

Rough board layout rendering attached...

sb100 top render (resized).png
#868 10 months ago
Quoted from cottonm4:

How fast do these bumper assemblies spin. What RPM? Would it be possible to buy a couple of high RPM motors, machine some brackets and machine the bumper part from hard rubber?
What about a motor from a Skil Saw. They are high speed with fast start up. They are continuous duty motors. And they have a threaded shaft.

there is some kind of PCB attached to them for the switch matrix.

6 months later
#1956 4 months ago
Quoted from jkashani:

I put leds in my inserts on my nine ball, hooked up the altek led driver board and attached the wire from the led board to a control lamp but I still am getting flicker? Compared it to my lightning with leds and I don’t think I I did anything wrong. Anyone have a similar issue? If someone had one that is working with leds can you advise as to where you hooked up the wire from the led board. Thank you

MPU200 games with the increased clock speed start to update the feature lamps when the feature lamp bus voltage is lower than Bally games. Because of that lamps are much more likely to "flicker" from lack of latching in Stern MPU200 games.

There are many variables as to why you may see flickering in one game over another. Feature lamp bus voltage differences from transformer variances. Line cord voltage. CPU clock speed. Resistance in connectors. Resistance in lamp sockets. And finely not all SCRs are created equal, it even varies in a lot from part to part. Recently i have tested On semi, UTC, and a Chinese brand from LCSC SCRs. The cheapest Chinese brand SCRs actually had the best performance for being able to latch at a low current... go figure.
https://datasheet.lcsc.com/szlcsc/Changjiang-Electronics-Tech-CJ-MCR100-6_C77884.pdf

When I am testing these lamp boards I use Big Game software, 3mm red led with 1k ohm current limiting resistor and a 560 ohm load resistor. After letting the board get warmed up if every SCR latches at that point it should be safe to use in about any game.

If you have a MPU200 or other game with a replacement lamp driver yet a few lamps still flicker the easiest fix for you to do is to add more load by putting a resistor across the lamp socket. 470ohm to 1k ohm should be sufficient. Just right across the lamp leads on the playfield.

#1971 4 months ago
Quoted from jkashani:

Would non ghosting LED's work?

probably not. I think the non ghosting ones have rectifier diodes and a capacitor inside of them, but nothing to add load.

If someone had LED lamps made with a built in resistor wired across the leads it could make the replacement LED boards with loading resistors not needed.

A software change to make the feature lamps update farther away from the zero cross point when the feature lamp voltage is higher would probably eliminate the need loading for resistors too. The original idea with incandescent was to turn on the lamps close to zero volts as possible to reduce wear on the lamp filaments... but that makes the LEDs not pull enough current to latch the SCR and you get flickering.

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