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ADC Super 6

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    ADC Super 6

    My ADC Super 6 works great with the S-100 Computer Group's IDE/CF card as a "hard drive". Sixteen 8 MB "drives". One thing bothers me: I can't reset the Super 6. I've chased reset* around on the board, and it seems to go to all the places I'd expect (CPU, peripheral chips, etc.), but it won't reset the system. I have to power cycle it to do so. Any Super 6 users out there? If I had to guess, I'd say that there's a flip-flop on the card that only gets reset with a power cycle, but who knows?? Any hints greatly appreciated.

    Roger

    #2
    I just went thru the same symptom a few months ago. It ended up being capacitor C10. Change C4 and C10. They are both RC timers for reset. I think one is power on and the other is button.
    Mine sometimes wouldn't boot at power up and not respond to reset button. Changing both those fixed it all. C10 is circled on the board photo.

    reset 2.PNG
    Attached Files

    Comment


      #3
      Thanks!!! Can't wait to try this out. If this works, I owe you big time. I never would have found this on my own.

      BTW, just to be rigorously correct: It is C9 and C10, not C4 and C10 (I agree -- it looks like a '4' on the schematic). The BOM with my documentation shows C9 and C10. C4 is a .1uf bypass cap on a 74LS04. I want to be sure that the info. is correct in case another ADC Super 6 user stumbles across this thread!

      Roger

      Comment


        #4
        Yes you're correct, C9. I looked at my card and it's the cap right above C10. My photo was before I replaced C9. The schematic is horrible quality
        I have a vacuum station and still had a hard time getting those caps out so only changed those two - C9 and C10. I remember mistaking that cap
        the first time around for a C4. I had the card up on an extender and measured the voltage on C10 and instead of ramping up to 5V at power on it just
        floated around at 2 to 3V so it was leaky, same for C9. I know techs say replace ALL caps but there's a hell of alot of them on this board and the
        two slaves I'm running. It's been running great all summer. Here's a youtube of it running it's current configuration.

        https://youtu.be/hU10bZ3igVM

        Larry G



        Comment


          #5
          Hi Larry -- no joy! I replaced both C9 and C10 with brand new 4.7 uf tantalum caps. No change. System doesn't produce a monitor prompt at initial power on, but a power cycle at that point will get the monitor prompt. Everything seems normal from there, but if I ever have the need to press the reset switch, I get a hang. A power cycle will get the monitor prompt back. I checked reset at the Z80 and the SIO/DART and it goes low at both places with a press of the reset switch.

          The old caps. both show ~4.7 uf with my DMM. Upon closer inspection, it appears that somebody had messed with those two caps. before. Evidence of resolder on the board.

          Neat video of your system! I only have the CPU board (no slave gear), so something like that is out of my reach!

          Roger

          Comment


            #6
            I was looking over my Facebook post about C10 and the polarity marked on the board is reverse !! I caught it before I installed the cap. I don't know if that makes a difference but
            it might. My symptom was exactly like yours. Here is the FB post
            https://www.facebook.com/groups/1302.../search/?q=c10

            Larry

            Comment


              #7
              I reversed C10, but nothing changed. I was hoping to fix this, but I guess I'm stuck with power cycling the box.

              Roger

              Comment


                #8
                I pulled both C9 and C10 and spent some time probing the connections around the two of them. It seems to me that the silk screen is reversed for *both* of them! I'm not good at reading schematics, so I could be very wrong. On the schematic, it seems to me that the positive leg of both are facing each other? With that assumption, it seems to me that the positive symbol on the silk screen for both is reversed, and the positive legs should be toward the bottom of the board, not the top. Anyway, I soldered them in again in that orientation, and there is no change. So .... is it possible that one of the ICs around them, U14, U15, or U4, could have been damaged by the wrong polarity? Or maybe CR01??

                Mystified.

                Roger

                Comment


                  #9
                  yes the positive legs are facing each other. putting it in backwards wouldn't have damaged any chips since there are 27K resistors to the 5V line.
                  One thought, what are you using for a terminal ? Some terminals can be set to capture the reset to a local key.

                  Larry G

                  Comment


                    #10
                    True -- no obvious damage to the nearby chips. I replaced them with new, and nothing changed. I'm using a Wyse terminal at 19.2k, but not using it for reset. I have a dedicated reset switch. It is functioning properly. I can see the reset working on the IDE/CF card, and as I said, I chased reset* around on the Super 6, and it is going low at the CPU and CTC with a switch press.

                    Comment


                      #11
                      Still thinking out loud. Does the IDE/CF card have it's own boot rom? Manual reset will re-enable the boot rom on the ADC Master. Maybe there's a conflict.

                      Larry G

                      Comment


                        #12
                        >> Does the IDE/CF card have it's own boot rom?

                        No, actually the IDE/CF card looks like an 8255 on the S-100 bus. I have a 2732 EPROM in the Super 6 that has some code @ F800 that starts up the IDE/CF card.

                        Roger

                        Comment


                          #13
                          To eliminate the possibility of any sort of off-board conflict, I pulled all boards out of the backplane except the Super 6. No change in reset* behavior.

                          Here is a photo of my Super 6, in case it has been mis-jumpered?

                          sup6.jpg

                          Comment


                            #14
                            There's a shit ton of jumpers and I'm checking mine vs yours. I'll look for more but I see your console is set to 19200 and mine is 9600. Also I'm running 4MHz cpu and dma, yours are both
                            6MHz. I recall having issues with lockup at 6MHz

                            Comment


                              #15
                              Yes, I'm running it at 19.2k. Seems to work OK.

                              I think I saw something, somewhere, about DMA not working well at the higher clock. I'm not doing anything with DMA (or the FDC) at the moment.

                              I'm trying to understand what the difference is between reset* and power cycling the box. Maybe POC* is not being asserted with a reset? Should it be? Something I need to check. I am just guessing that something on the board retains its configuration when the power to it is maintained, but a power cycle resets and clears things?

                              Roger

                              Comment

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