Broken NES dogbone controller - how to fix?

[AdamAnt316]

Hello everyone. A friend of mine has a couple of NES toploaders, complete with dogbone controllers. Unfortunately, one of the dogbones recently stopped working, for some reason. Best I can tell, none of the button presses register at all. The contacts and pads are clean, and the cable has continuity. Might there be a way to fix it? My guess is that the chip might be to blame; I figured I might try and swap chips between the stricken dogbone controller and a standard brick controller, but the chip used in the dogbone is surface-mount compared to the standard through-hole type in the brick. Is there a known source for the surface mount chip these controllers used? If not, might there be a way to adapt the through-hole version for surface mounting? Thanks in advance!
-Adam

[APE992]

Hello everyone. A friend of mine has a couple of NES toploaders, complete with dogbone controllers. Unfortunately, one of the dogbones recently stopped working, for some reason. Best I can tell, none of the button presses register at all. The contacts and pads are clean, and the cable has continuity. Might there be a way to fix it? My guess is that the chip might be to blame; I figured I might try and swap chips between the stricken dogbone controller and a standard brick controller, but the chip used in the dogbone is surface-mount compared to the standard through-hole type in the brick. Is there a known source for the surface mount chip these controllers used? If not, might there be a way to adapt the through-hole version for surface mounting? Thanks in advance!
-Adam

Read the text off the chip and I can check to see if there is one.

The pins can be bent but if you aren't experienced in this it is as easy to break them off as it is to set fire to gasoline.

[AdamAnt316]

Read the text off the chip and I can check to see if there is one.

The pins can be bent but if you aren't experienced in this it is as easy to break them off as it is to set fire to gasoline.

Here's the text from the top of the chip:

T 94 15H
4021BF

The 'T' is larger than the rest of the text on top of the chip. Guessing the 94 15 is the date code.
-Adam

[Tokimemofan]

Here's the text from the top of the chip:

T 94 15H
4021BF

The 'T' is larger than the rest of the text on top of the chip. Guessing the 94 15 is the date code.
-Adam

4021BF is a standard IC part number, it is called an 8-stage Static Shift Register.

[AdamAnt316]

4021BF is a standard IC part number, it is called an 8-stage Static Shift Register.

Good to know. Do you happen to know of a source for this particular chip? So far, I have yet to find a source which sells just one. Again, thanks!
-Adam

[APE992]

http://www.ebay.com/itm/4021BF3A-Int...item231b71d4e1

Kinda pricy. There might be something out there that serves the same purpose but is a different part number but my brain has had all of three minutes to function.

[madman77]

The 4021BT should work as well, it's in the same SOP package.

[shadowkn55]

DIP package

http://search.digikey.com/us/en/prod...52-5-ND/585876

Surface mount

http://search.digikey.com/us/en/prod...5-5-ND/1023569

Less than a dollar each.

[AdamAnt316]

Thanks for the links. Purchased four of the surface mount 4021BTs from Digikey, and shipping didn't cost much more than the price of the ICs themselves (tip: USPS first class is much more reasonable than UPS or FedEx when it comes to shipping small orders). Once they arrive, the next adventure will be learning how to deal with soldering these tiny ICs, since this will mark the first time I've ever tried to solder SMDs...
-Adam

[Tokimemofan]

Thanks for the links. Purchased four of the surface mount 4021BTs from Digikey, and shipping didn't cost much more than the price of the ICs themselves (tip: USPS first class is much more reasonable than UPS or FedEx when it comes to shipping small orders). Once they arrive, the next adventure will be learning how to deal with soldering these tiny ICs, since this will mark the first time I've ever tried to solder SMDs...
-Adam

Use a 15 watt soldering iron with a sharp tip and you'll be fine, they aren't that hard to so unless the pins are a too close together like the cpus of the systems.

[jb143]

It also helps to hold the part down in some way. Tape on one half should work. Start with opposite corners to hold it in place and work from there. Also try to clean up what was left over as best as possible scrubbing with a toothbrush and alcohol and use a magnifying glass to look for any bridges before and after soldering. Heat up the pad/lead and add a quick dot of solder.

In the factory, SMT parts are soldered in place by running the boards through an oven. I've heard of people using toaster ovens at home but for this chips lead spacing you should be fine with a sharp tipped soldering iron as mentioned above.

[Niku-Sama]

arent the chips in a dog bone through hole?

[APE992]

arent the chips in a dog bone through hole?

Typically I don't argue with a man who has the hardware open in front of him though I wouldn't be surprised if some models were.

[AdamAnt316]

arent the chips in a dog bone through hole?

I've seen pictures of dogbones which indeed have older-style boards with through-hole chips in them, on the opposite side of the board than the side with the pads. This one, however, seems to have been made near the end of the Toploader's short production run, and has a SMD chip on the same side of the board as the pads. Exactly why they made this change, I have no idea; I kinda wish they hadn't, since I have no experience with surface mount soldering.

It also helps to hold the part down in some way. Tape on one half should work. Start with opposite corners to hold it in place and work from there. Also try to clean up what was left over as best as possible scrubbing with a toothbrush and alcohol and use a magnifying glass to look for any bridges before and after soldering. Heat up the pad/lead and add a quick dot of solder.

In the factory, SMT parts are soldered in place by running the boards through an oven. I've heard of people using toaster ovens at home but for this chips lead spacing you should be fine with a sharp tipped soldering iron as mentioned above.

Thanks for the tips! What would be the best way to remove the original part? I was considering using solder wick, since that's what I'm used to, but I'm not sure if it'd be effective for this sort of application. Would one of those spring-loaded solder suckers be a better choice, or a dedicated de-soldering iron? Maybe something else? Again, thanks!
-Adam

[APE992]

Surface mount makes producing PCBs as well as the production of the entire product cheaper and faster to put together. With through hole you have to drill holes in the board which takes a lot more time. Obviously some holes were drilled but less holes=less time=less cost=larger profit margin.

Wouldn't surprise me if the parts they were using became more expensive in a DIP packaging over SOP or SOIC packaging making it more cost effective to switch over. It is rather hard these days to find anything but TSOP based flash for anything over 16mb that is cost effective. You can use banking to achieve the same result but it is not cost effective or conservative with space.

A good way to remove the original part is to take a pair of fine wire cutters and clip the pins starting from one end going to the other. Clip the leading edge and gently push the bit hanging out upwards then move onto the next. But be damned sure you have cut through it completely before trying to bend the remaining bit up as it is very easy to lift a pad giving yourself more work than you bargained for. Once the chip is fully clipped you can use your soldering iron to melt the solder under what is left of the pins and push them off the pad. Be sure its fully molten as you can still lift the pad without much effort.

Then flux the pads, align the chip, tack all four corners down, and go to town on the rest.

[bust3dstr8]

If you are in the Boston South Shore area let me know if you want a hand.
I have a hot iron desolder tip for SOIC chips and lots of parts boards if you want
to practice a bit first.

[jb143]

A good way to remove the original part is to take a pair of fine wire cutters and clip the pins starting from one end going to the other. Clip the leading edge and gently push the bit hanging out upwards then move onto the next. But be damned sure you have cut through it completely before trying to bend the remaining bit up as it is very easy to lift a pad giving yourself more work than you bargained for. Once the chip is fully clipped you can use your soldering iron to melt the solder under what is left of the pins and push them off the pad. Be sure its fully molten as you can still lift the pad without much effort.

This.

At my last job I had access to hot air rework tools which makes removing SMT parts a breeze. Aside from that I'd just clip them. Something else you can try is to heat each pad and bend the leads up one at a time with a dental pick, safety pin, or something similar.

[APE992]

I've used needles before but you need to be DAMNED sure you have that solder 100% melted or else you'll pull the pad giving you more work than you bargained for.

Since the part is bad there is no need to not clip it. I've removed other parts from other consoles that I do want to keep but need replacing (bad BIOS flash for example) and obviously this method doesn't apply.

[Tokimemofan]

Cut the chip out, then wipe it with a soldering iron to remove the leads.