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Taito Phoenix mod


BIG Trev

Question

Has anyone seen this mod before? I'm wondering what it was for.

Pins 1 and 2 of IC36 go to pin 10 on the card edge connector, pin 3 of IC36 goes to pin 8 of IC45 via a signal diode and pin L on the edge connector goes to gnd (pins 1,2 & 3 A,B & C) on the edge connector?

IC36 is a 7400 and IC45 is a MC14006B. It looks like a button would go between pin 10 and pin L on the edge connector and would ground the inputs of the nand gate on the 7400 (pins 1 and 2) and the output of this gate (pin 3) goes off to pin 8 of the MC14006B. The terminals on the card edge connector for the jamma adaptor for these two pins aren't used. I'm just wondering if I could remove this mod without causing problems seeing that it's not connected to anything?

Any ideas

Cheers Trev 75e2d1dbcda27653cfd30f5af8defc5d.jpg988084f44065e75e5aca2112be2c2646.jpg

 

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I'm guessing this would have been to reduce noise as they'd run a cable to a remote volume pot.e0800301f6858155d65ad9d86aec9313.jpg

This one I'm not too sure about.c62bead61ebfde1c3accaa40aca33ead.jpg

I'd say it's for noise reduction on the enable line. Just guessing though.

Cheers Trev

 

Sent from my SM-G930F using Tapatalk

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Lots of mods were done to video boards for a multitude of reasons. Sometimes to make a clean signal, noise reduction and often to get the machine to auto reset if it failed to boot correctly.

Caps across terminals are often inserted to stop voltage dipping which could result in board lockups.

 

Link wires can be installed to prevent voltage drop that was not an issue when the board was brand new but becomes apparent as the board ages.

 

Some mods were under board makers advice when common problems were told to them.

 

I look at such mods as being necessary or why did someone bother to put them on the board.

 

Removing them may not be apparent exactly what they do when you remove them but may appear over time.

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