Galaxian board missing sounds

videodan

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I just acquired a working Galaxian board that is missing the Fire and Explosion sounds. Which chips control these 2 sounds? With any luck, I can swap them out with 2 other non-working boards I have. Thanks!
 
Last time I worked on a galaxian board that was missing the shoot and explosion sound it was the LM324 at 7T. it could also be that 4066 analog mux switch but I think it is more likely the be the 324.

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If you're ever having problems desoldering chips, the problem is usually not getting enough heat into the joints.

One trick is to flow good, fresh solder onto each pin first. Then leave your iron (or the gun, whatever you are using) on each pin a little longer before you suck, to let the heat soak in more.

You don't want to force anything. If the chip doesn't come loose, flow fresh solder on the pins again, and repeat. Sometimes it takes a few passes. Especially if any of the legs are connected to fat traces for power and/or ground.

Another option is to cut the chip out with some diagonal snips, holding the cutters vertically, and cutting flush against the package (basically leaving as much of the leg on the board as possible.) Then you can remove each leg from the parts side with a tweezers and your iron. Then suck the solder out of each hole.

And for analog chips like these 324's and 4066's, it's usually a good idea to install a socket. They are frequent failures.
 
when desoldering (with Hakko FR-301) I touch to solder pad, then try to go around the pin in a circular motion to heat up (much like andrewb said) and while sucking the solder continue the circular motion. it will get the solder from around the pin more effectively. lately I've been running at the 2.5 setting, I was working on PC motherboards and that was the magic potion for multi layer boards. I think the idea is it will heat up faster this way so you spend less time on the pad. for regular iron because I've been mostly working with pinball MPU/driver boards and replacing a lot of header pins, I use 750 F instead of my usual 650 F. same concept, hotter so you don't stay on as long I guess, but I need it for flowing solder better.

I haven't worked on a Galaxian in years but if the chips were soldered like the 8080 games Midway hooked the chip legs, so you have the added task of trying to pull the leg back to get it to stick up so you can get around it. (emphasis: pull back the leg, let it cool first, then try to desolder if you do it this way) I think the Space Invader boards I worked on last summer I just cut the chips out and plunked the legs with pliers and regular iron after.

much of the older Midway games have very fine traces and they'll break off from the pads. I always test the solder pads with continuity mode on meter on the component and solder side pads to ensure the through hole plating is still intact, then test outward to next points in circuit to verify the traces are still connected. I don't know if it's a byproduct of perfectionism or just my clinical OCD but I had enough accidents in the past that I quadruple check these things very thoroughly before installing a socket. hopefully this helps.
 
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