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Thank you. Although I'm used to Arduino and ESP programming it is still a bit overwhelming at this stage.
Was looking at a TL866 with pin attachments. Any other recommendations?
Is there a specific way to "jump" power to other parts of a PCB? (e.g. if the chips on the back does not get enough volts).
Can you just, for example, solder wires from the JAMMA harness to the Vcc and GND pins of a EPROM or is there a cleaner way?
Or you have some incredibly corroded sockets or chip legs, or chip legs (e.g., Namco customs) that have legs which seem to dematerialize at times.The chips on a board should all be getting the same voltage. There shouldn't be a big enough difference to matter.
If that's not the case, you're measuring things wrong, or are missing something in your understanding.
Make sure the pin you think should be 5V is actually a 5V pin. Some chips do not have the 5V power pins in the corners of the chips.
What board and what pins are you measuring that makes you think the voltage is low?
Or you have some incredibly corroded sockets or chip legs, or chip legs (e.g., Namco customs) that have legs which seem to dematerialize at times.
I agree.Yes. In which case adding more voltage is not what you would want to do. (And that would also fall under 'missing something in your understanding').
I'm referring to this:The chips on a board should all be getting the same voltage. There shouldn't be a big enough difference to matter.
If that's not the case, you're measuring things wrong, or are missing something in your understanding.
Make sure the pin you think should be 5V is actually a 5V pin. Some chips do not have the 5V power pins in the corners of the chips.
What board and what pins are you measuring that makes you think the voltage is low?
I'm struggling with this concept.Check the voltage at the chips as far away from the power input as possible, volt drop across a board is normal, you many have 5V at the input of the board, but if that's dropped to 4.5V at the farthest reaches of the board then things will get screwy. Either up the voltage a tad, or run a power wire to the far side of the board, operators often did this back in the arcade heyday
I'm referring to this:
I'm struggling with this concept.
I'm working on a Namco Tekken 2 board where the PSU is set at, for example, 5V. When the PCB is not connected to the JAMMA harness, the Vcc and GND of the JAMMA harness measures 5V too. When the PCB is connected, the voltage measurement at on the JAMMA pins of the PCB measures 4.7V. The chips on the PCB also measures more or less 4.7V.
Is this drop to be expected or does it mean there is a problem that needs fixing (or to be "worked"), e.g. checking caps?
There is a lot of info on the internet that say to simply increase the voltage on the PSU, so I get the impression the voltage drop is to be expected...
In my example, do you up the PSU a tad, or do you run a power wire to the back? If not, when would be a good example to run a wire to the back?
Also, where do you run the power cable from (and where to)? From the power supply or the JAMMA input pins.
Lastly, do you only run Vcc or do you run a GND wire too?
What Womble said is wrong. He's mixing up two different things.
You don't get voltage drop across the board. What happens is there is voltage drop in the wiring harness, as well as the edge connector.
Is this a case scenario where you jump wires to the back of the board?Actually you do. Measure the +5v at the JAMMA connector pads. Measure it at a chip close to the JAMMA connector, measure it at a chip at the other end of the board. Measure it at a chip on a daughterboard. They will vary slightly in a well designed board and greatly in a poorly designed one. It's common to see 1 to 2 tenths of a voltage drop on the video PCB vs the CPU PCB on Galaga.
Is this a case scenario where you jump wires to the back of the board?
Never, ever?No. You never want to do that.
Never, ever?