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Taito Speed Race Resto (I hope)

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Post up your Arcade Cab restorations logs and pictures here

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  • #16
    Hi, there is a manual with wiring diagram available for the standard version which is probably very similar:

    https://www.arcade-museum.com/manual...20SP070029.pdf

    This might help you to identify some of the wiring, power connections to the game PCB etc.

    Regards, John
    more from John's Retro Workshop - www.jbtech.linkpc.net

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    • #17
      Originally posted by jbtech View Post
      Hi, there is a manual with wiring diagram available for the standard version which is probably very similar:

      https://www.arcade-museum.com/manual...20SP070029.pdf

      This might help you to identify some of the wiring, power connections to the game PCB etc.

      Regards, John
      Thanks John

      The Deluxe version of this game is very different from the original. I think you are right that the wire colors in this manual may be a guide but the wiring is completely different.

      Thanks

      Axel

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      • #18
        Originally posted by Autosteve View Post
        This picture shows two plugs. The one with the stick on letter is original Taito. Any other plugs used in the base of the machine I would regard as non standard. There should be a different style but still Taito used around the monitor but they should still have the same style stickers on them.

        https://www.aussiearcade.com/filedat...4&d=1623040529

        As for Peter Chow arcade power supplys, ( not transformers), I don't think they still go under that name and I'm not sure whether that game required the negative voltages....-5 and -12vDC. Look at the voltages on the existing power supply and it's wires. Taito use different wire colours for different voltages so you should be fine to trace what each voltage is.

        The voltages you will require are 5vDC, 12vDC but you may require -5vDC and -12vDC as well. Not real sure about that. See if these terminals are on the existing power supply or if they are used.
        Thanks again Autosteve The original transformer in the cabinet drives 100V for the monitor and I am assuming a fluro light behind the marquee as well as outputting 9V at 5A and 9V / 17V at 3A - I assume to drive the power supply.

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        • #19
          Axle some of these earlier PCB's required a +12vdc, +5vdc & a -5vdc. Can't say if Speed race did but you'll want to be sure. Also the Tranny outputs after being rectified will be lower if their DC measurements.

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          • #20
            I have done some basic diagraming to hopefully provide a schematic wiring diagram for my machine.

            Plug B is the power input plug.

            Now for the million dollar question - What wire feed what voltages to the board?

            Click image for larger version  Name:	Speed Race 1 Master (1).jpg Views:	0 Size:	292.8 KB ID:	2213859

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            • #21
              Hi, the safest way to be sure is to double check the game PCB and confirm which edge connector pins go to the power input pins on the logic ICs

              comparing your drawing with your photo of the game PCB it looks like pins 1,2 and 3 on the component side of the PCB edge connector are ground (black wires)

              and I suspect +5v is the red wire which connects to pins 6,7,9 and 10 on the solder side of the PCB edge connector, with pin 8 being the keyslot

              So if you use a meter (or even visually looking at the PCB tracks) you could check if these edge connector pins go to the Vcc (+5V) and ground pins on the logic ICs

              - find a datasheet online for any of the logic ICs on the board to help identify the correct pins if that helps, most commonly for say a 16 pin IC +5 would be pin 16 ( top right pin, with the notch being the top) and ground would be pin 8 being the bottom left pin, diagonally opposite. A small dot indent next to the notch (top left) indicates pin 1.

              If those two wires are confirmed as +5 and ground then I would suspect the orange wires on Pins 9 and 10 on the component side of the edge connector may be +12V but would double check where these connect to on the game PCB and steering wheel just to confirm. Most logic circuits without memory or microprocessor don't need +12V but this could be used to power the analog part (steering) or an audio amplifier on the game PCB or may be used for a 12V indicator light on the control panel.

              If there was prior modification to the power wiring the 3 pin Molex style connector may have been used so the game could be powered by an off the shelf arcade type power supply with orange, red and black being +12, +5 and ground.

              I don't think your PCB would have needed -5V but there is another way to double check the PCB:-

              Look for the large electrolytic capacitors. These are usually used to filter noise and hum from the power supply rails. They have a + lead and a - lead

              for a positive supply rail (e.g. +5V or +12V ) the - pin of the capacitor would go to ground and the + pin of the capacitor would connect to the + voltage.

              If there is a negative supply (i.e. -5V) a capacitor would have its + pin connected to ground and the - pin would connect to the negative supply voltage.

              - Obviously it would be preferable to find the correct documentation for your exact model or compare yours to another unit which is identical but if that isn't possible hopefully the above method will be helpful.

              Regards, John
              more from John's Retro Workshop - www.jbtech.linkpc.net

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              • #22
                I now have power to the main PCB and unfortunately no output to the monitor.

                I have checked all of the resistors and capacitors and found one resistor that looks to need replacement and one capacitor that has a broken leg. The capacitor is a greencap with the marking "0.1 50WV" whic I assume mean "0.1uf 50V". Not knowing alot about capacitors and the different types, I am looking for input as to what type of cap I should replace it with?

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                There also seems to be a spot on the board where a component looks to have been removed at some point (see attached photo). I suspect it is another capacitor...


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                On JBTech's suggestion I have ordered a logic probe to start checking for activity at the chips.

                Without a schematic this is quite a puzzle.

                Any input gratefully received.​​​
                Attached Files

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                • #23
                  Caps are Ceramic type, a dime a dozen, The Xtal is for a crystal so that's important & it's not a cap. If it's used you'll need to find out the fequencey eg, 4.7654mhz this is just an example don't look for this example. It's used to time the clock pulse on the i.c.

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                  • #24
                    Originally posted by Gemini2544 View Post
                    Caps are Ceramic type, a dime a dozen, The Xtal is for a crystal so that's important & it's not a cap. If it's used you'll need to find out the fequencey eg, 4.7654mhz this is just an example don't look for this example. It's used to time the clock pulse on the i.c.
                    The wheels board which I believe is very similar uses a 4.75MHz as best I can see. I also saw taito post where he was looking for one for his game which used a 14.314MHz crystal

                    https://www.aussiearcade.com/forum/a...for-speed-race

                    It looks like these are really not available any more so my repair activities are at a stand still :-(

                    Extract from the Wheels schematic:
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                    • #25
                      Ax, maybe look into cleaning the board before you start working on it. It will be hard getting logic probe signals with all that crud on all the I.C legs.

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                      • #26
                        o
                        Originally posted by AxedBandit View Post

                        The wheels board which I believe is very similar uses a 4.75MHz as best I can see. I also saw taito post where he was looking for one for his game which used a 14.314MHz crystal

                        https://www.aussiearcade.com/forum/a...for-speed-race

                        It looks like these are really not available any more so my repair activities are at a stand still :-(

                        Extract from the Wheels schematic:
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                        Someone will have one maybe used but still working. Also you used to be able to get custom crystals cut so look into that too.

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                        • #27
                          @Kaizen said he had heaps on that thread.

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                          • #28
                            Originally posted by Gemini2544 View Post
                            Ax, maybe look into cleaning the board before you start working on it. It will be hard getting logic probe signals with all that crud on all the I.C legs.
                            Yep - had a go at cleaning some of the paint of the chips today and it does show some of the chip markings but most have been scratched out.

                            What would you use to clean the chip legs Gemini2544 ?

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                            • #29
                              A soak in vinegar and warm water and a good rinse works but others might have something more hi tech.

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                              • #30
                                Hi, well done spotting the missing crystal!

                                - Without it the crystal oscillator will not run and there would be virtually no activity on the PCB at all including no video or sync as just about all signals on the PCB would be derived in some way from the master clock frequency.

                                I read the previous thread about the crystal frequency, it seems the original 14.314 MHz is not readily available but 14.31818 is relatively common - I have to say that the latter frequency is so close, within 0.03% of the original I don't believe there would be any noticeable difference to the operation of the circuit and doubt any tearing or rolling of the graphics would have been due to that difference. If the main clock frequency is just that tiny bit higher all parts of the circuit should be affected equally...

                                So if you can't source the original frequency crystal but are able to obtain the 14.31818 I'd definitely try that one. It will hopefully get the board running with some output for starters. It should also be possible to 'pull' the oscillator frequency back down by adding a small capacitance and checking with a frequency counter but I really doubt it would be necessary at all.

                                The 0.1 uF greencap is easily obtained from Jaycar, Element14 or pretty well any component supplier. They might be marked 0.1 like the original or they might be labelled 104 which is 1 0 0000 picoFarad, the same as 100 nanoFarad or 0.1 microFarad. That one may just be acting as a noise filter on the PCB and not urgently required but worth installing a new one in any case.

                                Regards, John
                                more from John's Retro Workshop - www.jbtech.linkpc.net

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