(Topic ID: 175637)

Stern MPU to sound board ribbon cable

By G-P-E

4 years ago


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  • 28 posts
  • 12 Pinsiders participating
  • Latest reply 6 months ago by barakandl
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    #1 4 years ago

    Memory faded and trying to remember...
    Original Stern MPU to sound board ribbon cables -- single row and I believe they used two 17-pin ribbon cables that were 1x17 with 0.1" centers? Is this correct?

    #2 4 years ago

    No, if talking about the SB-300.
    The header on both boards was 34 pins long, .100". However, the ribbon cables were 2x 16 pin. The last two pins were left unconnected.

    Edit: Apparently, games came with anything between 2x16 and 1x16 + 1x18.

    #3 4 years ago

    My F2K had two 17 pin ribbon cables.

    #4 4 years ago

    My Star Gazer has a 16 and 18. No foolin'. I counted three times to be sure.

    #5 4 years ago
    Quoted from stangbat:

    My Star Gazer has a 16 and 18. No foolin'. I counted three times to be sure.

    The one in my meteor was also 16 and 18 IDC...now, were those cables actually there in 1979...that I don't know.

    #6 4 years ago

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    #7 4 years ago

    Interesting - you have two 16pins, but one is connected to a 18pin header. Mine's on two 16pin headers.

    Absolutely strange the amount of difference.

    Anyone know if those two signals - A14 and IRQ should be connected or not? I actually need a new set of cables, and was hesitant on getting 1-16pin and 1-18pin cable, since my game didn't originally have that in it.

    Assuming GPE is going to be making cables. If they're thinking about re-doing the sound board, I would recommend adding a second, mirrored header, .050" 2-row 34pin, for newer ribbon cables.

    #8 4 years ago

    Found this on Pinwiki (I should have looked there first!):

    "The Stern SB-300 sound board was used in all games which used the M-200 MPU board. The SB-300 is interfaced to the MPU board via the 34 pin J5 connector located at the top of the board. Note that the sound board only uses pins 1-32 on its J1 connection. Some ribbon cables used were 2 - 16 pin connections, while others were 2 - 17 pin connections, or a combination of the two. Make certain that pin 34 of the sound board is not connected to the MPU. Pin 34 on J1 of the sound board and pin 34 on J5 of the MPU board is the /IRQ signal. This signal is never used by the sound board. However, if it is connected to the MPU board from the sound board, it can sometimes cause the MPU to lock up or hang. Either bend pin 34 of J1 on the sound board away from the connector (if it is even connected), or snip the pin off completely."

    A14 is not used on the sound board BUT the IRQ signal is connected to the IRQ on the sound board... AND you don't want the sound board IRQ to be hooked up. This would explain the 2x 16 pin plugs. Or the 2nd using an 18 pin plug with two last pins not used.

    I have a source for the 0.1" ribbon cable (very tough to find!) as well as crimp on 0.1" single row plugs (also very tough to find). I'm going to try for 16 conductor cable and 16 pin plugs and see if I can get them.

    Next question -- what was the typical length for these?

    Thanks guys,
    Ed

    #9 4 years ago

    Ed,

    The cable that I have is 12 inches in length - plus the connectors.

    I checked the photos from my Flight 2000 (MPU 200) and they are 2 X 17 and all pins are connected to the sound board (but I don't know if it's SB300)

    The Trident (MPU 100) also had 2 X 17 pin connectors.

    I'm working on a Meteor for a friend (MPU 200) and it had only 2 X 16 connectors and I thought that was incorrect and found a 2 pin connector that we were going to use. Now I don't know if that is needed. So far none of the boards have been reinstalled so I can't test if the 2 two 16's will work.

    Glad to see that you are going to make these cables - let us know when they are ready.

    Thanks

    Bob

    PHOTO OF F2K:

    IMG_2046 (resized).JPG

    #10 4 years ago

    Thx.
    I'm thinking two identical cables, with 17's at 12" long is the way to go. For those that don't want the IRQ connected, notch that connection on the ribbon cable.

    Ed

    #11 4 years ago

    I bought a pair of these and installed on a friend's Seawitch. Worked great.
    ebay.com link: Orignal Stern Pinball Sound Cable SB 100 300 DUAL GOLD PIN

    #13 4 years ago

    This is something I think is really needed. On all my machines I replace the connector headers and the crimp-on connectors but there’s not much you can do for the ribbon cable except reuse the old one and hope.

    I’d also like to see you make it idiot proof. One cable has a key but the other cable can be inverted on one end. Also one time I plugged in the second cable but missed a pin in the middle. Took me all day to find the problem. A 34 pin connector plug with a key would be great but I don’t know if that’s available.

    #14 4 years ago

    You could glue the two cable together. That's what I did.

    #15 4 years ago
    Quoted from oldschoolbob:

    I’d also like to see you make it idiot proof. One cable has a key but the other cable can be inverted on one end. Also one time I plugged in the second cable but missed a pin in the middle. Took me all day to find the problem. A 34 pin connector plug with a key would be great but I don’t know if that’s available.

    I offer keyed cables, labeled left and right per mpu side and sound board side here: http://pinitech.com/products/cat_cables.php. Label also has markings for pin 1, 16 and 17, 34..as well as a dot. Fully idiot proofed enough, but also includes instructions DIY kits also available.

    An IDC solution would be the far quicker way to build and thus offer a cheaper solution. Spent weeks of time myself trying to track down the parts a few years ago but hard enough finding single row IDC & 2.54mm pitch ribbon cables, let alone at reasonable prices.

    #16 4 years ago

    New ribbon cables would probably sell well. The originals rip at the ends. Def only make them 1x16. 100% of the time the last two pins do not need connected and may cause problems when it is. When the IRQ pin goes the 6840 square wave making chip, it will sometimes lock up the MPU. You can either bend the IRQ pin out of the socket on the 6840 sound board chip or leave it off the connector.

    My Big Game came with a 1x16 and a 1x18 FWIW. Meteor had two 1x16. Who knows if that is what they came with form the factory/

    You can also build your own connectors for these. Its not hard, just time consuming. Normal 0.100" molex crimp and housing fits.

    #17 4 years ago
    Quoted from barakandl:

    New ribbon cables would probably sell well. The originals rip at the ends. Def only make them 1x16. 100% of the time the last two pins do not need connected and may cause problems when it is. When the IRQ pin goes the 6840 square wave making chip, it will sometimes lock up the MPU. You can either bend the IRQ pin out of the socket on the 6840 sound board chip or leave it off the connector.
    My Big Game came with a 1x16 and a 1x18 FWIW. Meteor had two 1x16. Who knows if that is what they came with form the factory/
    You can also build your own connectors for these. Its not hard, just time consuming. Normal 0.100" molex crimp and housing fits.

    Here's my take. Some people are going to have two 1x17 cables, or a 1x16 and 1x18. Others may have two 1x16 cables in their game. In terms of someone replacing what they have, people that currently have all the pins covered with their cables are going to think it's odd leaving those pins disconnected... you can explain it, you can point them to posts on RGP or Pinside -- but some people are going to want to replace exact with exact. That, along with others having offered them as 34-pin cables is why I have offered both versions as well since 2013 or 2014. It may also throw the next person buying the game too if they see pins left unconnected. Fully understood that IRQ could cause issues, but it's when the 6840 is bad isn't it? So it may happen sometimes, but it's not that it's always the case. Worst case, someone cuts those wires or pulls the wire out of the Molex header if they're having issues.. easy fix. I'm not sure if I'd like cutting into the ribbon cable personally, I'd rather just cut individual wires or pop the terminals from the connectors, but that may just be me.

    #18 4 years ago
    Quoted from acebathound:

    Here's my take. Some people are going to have two 1x17 cables, or a 1x16 and 1x18. Others may have two 1x16 cables in their game. In terms of someone replacing what they have, people that currently have all the pins covered with their cables are going to think it's odd leaving those pins disconnected... you can explain it, you can point them to posts on RGP or Pinside -- but some people are going to want to replace exact with exact. That, along with others having offered them as 34-pin cables is why I have offered both versions as well since 2013 or 2014. It may also throw the next person buying the game too if they see pins left unconnected. Fully understood that IRQ could cause issues, but it's when the 6840 is bad isn't it? So it may happen sometimes, but it's not that it's always the case. Worst case, someone cuts those wires or pulls the wire out of the Molex header if they're having issues.. easy fix. I'm not sure if I'd like cutting into the ribbon cable personally, I'd rather just cut individual wires or pop the terminals from the connectors, but that may just be me.

    Every SB300 I fix the i pull out the IRQ pin out of the socket on the 6840. It is happy just floating in the breeze. That just avoids potential issues.

    Appears to be a timing issue of some sort. Swapping boards around it seems it is not necessarily the 6840, but the combination of a the MPU, the 6840 and the sound board.

    #19 4 years ago
    Quoted from barakandl:

    Every SB300 I fix the i pull out the IRQ pin out of the socket on the 6840. It is happy just floating in the breeze. That just avoids potential issues.
    It is a timing issue of some sort. Not necessarily the 6840, the combination of a the MPU, the 6840 and the sound board.

    I'd think in that case putting a label/sticker on the board indicating why it was done would be good then. There's many times components are added to the back of the board either by the factory or by others as part of a service-bulletin and until you start digging it can look like someone was just playing around with the board trying to diagnose something or adding some pull-up or pull-down resistors. If I saw a board with a chip pin floating I'd wonder if it was someone's attempt at isolating a problem, or if it was a way to get the board working -- but there's some functionality missing. I'd probably reconnect the pin too.

    #20 4 years ago

    Would repro cables the same for SB-100 and SB-300?
    2x16 on SB-100 in my Lectronamo and they are not ribbon cables. Not sure if they are original or not but they sure have been there a long time.
    I also should note that the cables came with the machine when I got it but the sound board did not it was just easier to find the later version or SB-100

    IMG_5553 (resized).JPG

    #21 4 years ago
    Quoted from 20eyes:

    Would repro cables the same for SB-100 and SB-300?
    2x16 on SB-100 in my Lectronamo and they are not ribbon cables. Not sure if they are original or not but they sure have been there a long time.

    Kind of what's up for debate in this thread Technically the Stern SB-300 can operate fine with 2x 16-pin cables and since they J1 header on both the SB-100 and SB-300 are key'd at pin #29 they're interchangeable. What's being said here & on RGP over the last few years by barakandl & others is pins #33 and #34 on the SB-300 boards don't need to be connected and were left unconnected in some games that seem to have come with 2x 16-pin cables from the factory. Since the cables are a 1-to-1 pinout (meaning pin 1 to pin 1, pin 2 to pin 2, etc) then yes.. the same set of two 16-pin cables works on both the SB-100 and SB-300. Appears from the factory they came in any number of configurations -- crimped with Molex housings as in your photo. Ribbon cables. I think I've seen key'd and not key'd on the ribbon cables. Games with SB-300 sound boards may have had 2x 17-pin, 1x 16-pin and 1x 18-pin or 2x 16-pin cables.

    Yours look original IMO. I've seen multi-color wired use, but also same colored wires as well.

    #22 4 years ago

    Ok, I'm a bit slow but I'll catch up lol.
    My cables are fully populated aka no key on either cable.

    1 month later
    #23 4 years ago

    OK -- I finally received a bunch of Stern sound cables. Sell them in pairs. Either 2x 16 conductor or as 2x 17 conductor. This covers those that use 32 pin interconnect and 34 pin interconnect.
    No photo's yet, though. Gray cables, black plugs, black stripe for pin 1 indicator.

    They can be found here:
    https://www.greatplainselectronics.com/products.asp?cat=57

    #24 4 years ago

    Great job GPE. These are much needed. the others out there are expensive and poorly made.

    4 years later
    #25 6 months ago

    Resurrecting zombie posts before restocking ribbon cables.

    Does anybody know of an old Stern with an SB-300 that MUST have the 34th pin (IRQ) hooked up between the sound board and CPU board?

    For MPU-200/SB-300 connections:
    I have read posts that said if a 34-pin connection is used then some boards didn't function properly. Probably due to software mishanding of the IRQ.
    And some posts that have 34-pin connection installed, have IRQ disconnected and it works fine -- which says these CPUs do not use this IRQ.
    And some posts that have 34-pin connection installed, have IRQ connected and it works fine - which says CPU properly handles IRQ (don't know if it uses it, though).

    So what I need to know - do any boards *need* the IRQ signal on pin 34 to be passed from the SB-300 to the MPU-200? Can all these machines get by with just a pair of 16 pin connections? I know the following had 34 pin cables originally used (e.g. 2x17 or 1x18 cables) BUT can all the MPU-200/SB-300 machines use the same MPU-100 cables with a 32 pin count?

    The games affected:
    Meteor
    Galaxy
    Ali
    Big Game
    Seabitch
    Cheetah
    Quicksilver
    Stargazer
    Nine Ball
    Iron Maiden
    Viper
    Dragonfist
    Cue
    Flight 2000
    Freefall
    Lightning
    Split Second
    Catacomb
    Orbitor 1

    #26 6 months ago

    I had a look at the IRQ code in all those listed games.

    They all treat an IRQ that hasn't come from one of the PIAs as an unknown interrupt so force a system reboot.

    The interrupt vector points to code that first checks for an IRQ sourced from:
    ~ CA1 of U11 PIA - Display interrupt generator
    if not, then check:
    ~ CB1 of U10 PIA - Zero Crossing interrupt
    if not, then check:
    ~ CA1 of U10 PIA - Coin door self test button
    if not, the interrupt is from an unknown source so REBOOT the system.

    There's no check for the IRQ being sourced from the SB-300.

    #27 6 months ago

    Wow, now there's an answer!

    OK -- so apparently in the machines that do work properly with 34 pin plugs, they make sure that the 6840 timer doesn't generate an IRQ. This can done by making sure that the composite interrupt flag within the PTM is never set.

    Pin 33 carries A14 which is not used at all by the SB-300
    Pin 34 which carries the IRQ from the timer back to the CPU but if the IRQ occurs then the CPU doesn't know what to do and reboots.
    So this confirms that posts above and others in pinside and rec.games.pinball - these machines don't really need 34 pins connected, only 32. So it makes most sense to only stock cables for 32 pin connections.

    Thanks much, Ed

    #28 6 months ago

    It is best to use 32 pin cables and not hook up the IRQ. I have come across many SB300 boards (the 6840) where having the IRQ connected across MPU j5 to SB300 actually locks up the CPU. Never went down the rabbit hole as to why, but it is common fault on maybe 1/10 boards. Pretty sure Stern realized this could be a problem too as many SB300 games I have come across had 32 pin cables in it. I did not route the IRQ track on either the replacement SB300 or MPU at J5.

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