Replacing a video game cartridge battery without losing saved data

Back in the 8-bit and 16-bit video game days, a small number of game carts contained a battery in them. They used a small lithium battery to allow games to be saved on the cartridge. Before the 8-bit days I don't think they had saved games, and after the 16-bit days they used flash memory. So this is really a small number of 8-bit and 16-bit games that have batteries. But these batteries won't last forever, in fact most of them are probably dead by now. Amazingly enough I have a cartridge at home that still has saved game data 20 years later!

Replacing the battery isn't too difficult as long as you have some soldering skills, but doing so will erase any data saved on the cartridge. I own Phantasy Star 2 on the Sega Genesis (Mega Drive) that has some pretty incredible saved games that I want to preserve. So this is my attempt to replace the battery without losing saved games.

1. Opening the cartridge
This step may seem straightforward, but it may be more complex. The Sega Master System used standard philiips screws, but the Sega Genesis uses a security bit. So you may need to buy a security bit to open the cart, or find another creative way to open it. Once open you need to identify the type of battery. All Sega carts I've seen use a CR2032 lithium battery. Here are pictures of the front and back of Phantasy Star 2.




2. Buy replacement batteries
Once you know the type of battery you need to order replacement batteries. Yes, you need to order 2 batteries for this to work. I highly recommend you order "tabbed" batteries. Soldering directly onto batteries is difficult and can be dangerous. These replacement batteries should be fairly cheap. I got mine from newark for $2.57 each.


3. Add a battery in parallel
For this technique to work you need to solder a second battery onto the cartridge in parallel with the existing battery. In theory this battery will continue to provide power while replace the battery soldered into the cartridge itself. When soldering in this second battery be sure and get the polarity right.


4. Replace the battery
With the temporary battery in place, you can now desolder the old battery and solder in the new one. Removing the battery is very easy with a solder sucker, or you should be able to get it our using just solder wick. Once the original battery is out you can solder in the new one. You may need to bend the pins so they align with the holes in the circuit board. Also, as before make sure you get the polarity correct. Here's a picture of the new battery soldered to the board after I removed the temporary battery.


You can now reassemble the cartridge and try the game out. When I did here's what I got:


FAILURE! Crap, I just lost all my saved games.

So what happened? Well I can only think of one reason why this failed. Soldering requires very high temperatures, so the circuit traces around the battery were briefly subjected to temperatures in excess of several hundred degrees. A general rule of electricity is as temperature increases so does resistance. So my guess is the resistance increased causing a drop in voltage and current sufficient to cause a lose of stored data.

Is there a way to get around this and still make it happen? I can think of two ideas. First, if you used a voltage source higher than a single lithium battery (3.6V) the increased voltage might be enough to overcome the increased resistances from heat. Of course, this becomes tricky because too much voltage could "fry" the chips on the circuit board. The only other suggestion I can think of is to buy a retrode. This device allows you to read and write saved game info directly from the cartridge. So you could save the data to your computer, replace the battery, then restore the data.

Well even though my attempt was a failure, I'm glad I did it. It was a fun project, and these new batteries should last another 20 years.

What a crock

At home we recently got a new slow cooker (a.k.a. crock-pot), but I have to say I'm very disappointed. We've cooked several recipes in it and each was overcooked. I noticed with the crock pot set to low the contents were boiling. I'm sorry, it should not boil on low.

From what I can tell this is true of all new crock pots. Apparently manufactures have increased the cooking temperatures by about 20 degrees. So whereas low used to be about 185 degrees it's now 205, and high went from about 200 to 220. This change angers me. Most crock pot recipes are designed to cook at a certain temperature for a certain length of time. But by increasing the temperature now all recipes won't cook the same without guesstimating how much to decrease the cook time. Also, shorter cook times mean you can't put the food in before you leave for work and come home to a hot dinner. Instead you'll come home to a burned dinner.

Why did they do this you ask? Good question. Everything I've read says manufactures were afraid of being sued because the slower cooking crock pots left food in the "danger zone" longer. The "danger zone" being 40 degrees to 140 degrees, the temperatures most likely to encourage bacterial growth. But this is being overly paranoid. As long as you let the food cook completely there's nothing to worry about. If I take food out of the oven early before it's finish cooking I could get sick. But is that the ovens fault? No, it's my own stupid fault. The same is true with crock pots.

As you can tell I'm a little peeved here. I really enjoy crock pot cooking, but this new crock pot is going to make that difficult. If I ever find a crock pot with actual temperature control (not just low/high) I'll buy one. And if you have an older crock pot, pray that is lasts a long time.

Star Wars Lego ornaments

With Christmas fast approaching I thought it might be time for a Christmas related post. Last year I discovered a build your own Death Star Christmas tree ornament made out of Legos. This kit is not an official kit, so you can't buy it in stores. Instead, you need to log onto Lego's Pick a Brick website and order the pieces manually. I received this as a gift last Christmas, so this year is the first year our Christmas tree is decorated with a Lego Death Star.


This kit is "cool" on so many levels. It's Star Wars and it's Legos, both of which were a huge part of my childhood. Even though this kit is not official, it's done very nicely. The instructions are as easy to follow as a genuine kit. It's made out of genuine Lego pieces. And the end product looks very cool. I highly recommend this for any Star Wars and Lego fan. It is a bummer that you have to order the pieces manually. But the cost is reasonable. I believe it was just under $20, which included shipping.

New for this year is a build your own Millennium Falcon Christmas tree ornament Lego kit. I can see it now, in a few short years my Christmas tree will be nothing but Star Wars ornaments made out of Legos. :)

Elenco XP-720K

I recently built the Elenco XP-720K, a bench variable DC power supply that comes in kit form. This is my mini-review of that kit and the process.

My first impression of the kit was of the quality. For a relatively small device it had a lot of weight. The metal case for the power supply is from thick metal, not cheap and flimsy. The painting on the case is very nice, and all the components for the inside are of good quality as well. The instructions are clear and easy to follow. All and all it was a fun kit to build.

As I built the kit I didn't photographically document every step of the way, but if you want to check out pictures of someone else building the kit go here.

I did make several changes or "mods" to the design.

1. I replaced the provided potentiometers with some Bourns 10-turn pots (3590S-2-202L). With more turns I have greater control over accuracy. I can easily dial the output power to within 2 thousandths of a volt. I could have added some "fine-tuning" pots in series with these pots for greater accuracy, but I don't need that level of accuracy.
   
2. In addition to the new pots, I used metal knurled knobs from Kilo (OEJL-63-4-5).
   
3. I covered the connections with the voltage regulators in heat shrink tubing to prevent shorts.
   
4. Instead of the provided capacitors, I ordered new high-quality low-ESR Panasonic brand capacitors rated for power supply use. With these high-quality caps the power supply should run for a long time.
   

Here are some pictures of the changes I made to the original design.






If I had to do this over I think there is only one change I would make. The new knobs I used were 5/8" in diameter. I think I would use larger 3/4" or even 1" diameter.

Even though I'm very pleased with this kit, I can think of some improvements I would suggest to Elenco.

• The traces and the pads on the circuit board are too large. I suspect this is to make it easier for a beginner to solder, but it actually does the opposite. Because the there is so much copper on the board, it takes longer to heat the copper to get the solder to flow properly. So this actually makes it harder to solder.
  
• Soldering the 12 wires onto the voltage regulators was not the easiest. If there were some sort of clip to slide onto the regulators, or if the regulators were soldered onto a second board with a ribbon cable connector between them, it would make assembly easier would help in reliability.
  
• Use bridge rectifiers instead of 4 individual diodes. Fewer solder connections and would be quicker and easier.
  
• Offer a model that includes a built-in display for voltage. Always having to use a multimeter to dial-in the voltage will get old fast.
  
• Offer a model that is based around the switch-mode power supply design versus the linear design of the XP-720K. Sure it would cost more, but it would be more efficient and would be even more fun to build.
  

The Elenco XP-720K is a great kit and a useful product once complete. If you find yourself in need of a variable DC power supply, consider this product (or the smaller XP-15K).

Electrical surges addendum

In my last post I talked about electrical surges, how devices like vacuums generate them and how good-quality surge protectors guard against them. I can already see it, someone who it read is thinking "are you saying that a vacuum on the same circuit as a TV or computer without a surge protector would mean instant damage to the TV/computer?" Surely you can't be making that claim, because I've done just that before and the TV/computer still works, so your claims are false. Well, I don't claim this scenario will always result in damage to the TV/computer, but if you repeat this scenario eventually it will fail. Let me explain why this is.

The electricity coming into your house is AC (alternating current). The problem is very few devices use AC, most require DC (direct current). Therefore, every TV, computer, radio, etc. has an AC to DC power supply. Inside that power supply is the same protection circuitry located in a surge protector. That's why the device does not fail after one power spike.

"If the TV/computer protects itself against surges, why bother with a surge protector?" I'm glad you asked. The first reason is what I said in the last post - the circuity can only protect against X number of surges, after that it's useless. So if you don't use a surge protector eventually the TV will break and you'll have to replace or repair it, but if you use a surge protector you can replace the surge protector for much cheaper. The second reason is because the TV/computer probably contains a low-level of protection, i.e. it only protects against a low number of joules of energy. A good-quality surge protector will protect against more joules.

Also, if the TV/computer is on or off during the surge makes little difference. The device is probably more susceptible to surges when powered on, but may still be overloaded when turned off. The only way to truly protect it is by disconnecting it from the socket.

One final thing I'll mention is polarized AC plugs. You've probably noticed some AC plugs are polarized (one connector is larger than the other). If AC flows in both directions why is the plug polarized? The answer has to do with the protection circuitry. Manufactures put the protection circuitry on the "hot" wire and leave the "neutral" wire unprotected. Thus the polarized plug ensures the protection circuity is properly protecting the device. Manufactures could protect both the hot and neutral (and indeed some do), but this costs more money. If you've ever "forced" a polarized plug to fit the wrong way, the device was no longer protected. Also, if you have a wiring fault in your home, the device is unprotected as surges could come up the neutral wire. Both of these are still more reasons to use a good-quality surge protector. A good surge protector protects hot, neutral, and ground.

Electrical surges

Recently I learned some very useful info related to electrical surges and surge protection. An electrical surge can be described as additional voltage and/or current above and beyond the expected amounts. These surges can come from two main sources, outside your house (e.g. lightning strike) or inside your house (more on that later). Regardless of the source, a surge could easily damage newer electronic devices which are very sensitive to surges. Despite common believe, fuses do not protected against surges. Fuses only protect against too much current (amperes) not too much voltage.

Before I discuss protection, I wanted to talk a little more about surge sources. It's easy to understand surges external to your house - the most obvious example would be lightning strike. But surges generated inside your house are a little more difficult to understand. I won't go into the electrical science, but the short answer is any large inductive device has the potential to create voltage surges. The most common inductive device capable of generating large surges is large electrical motors. Whenever you turn off an electrical motor it creates a voltage surge on the household circuit on which it's connected. And yes you read that correctly, the surge is created after the motor is turned off, not before or during. This is one of the main reasons why refrigerators, washer and dryer, and air conditioners are typically on their own circuit. If other appliances were connected to the same circuit as these appliances they would get a surge every single time the motor switches off. There is however one large motor in your house which is not on a dedicated circuit - your vacuum cleaner. Vacuum cleaners have deceptively large powerful motors in them. It's not uncommon for a vacuum cleaner to pull 12 amps or more. That is a lot of power! So if you plug your vacuum cleaner into the same circuit as your expensive TV or computer, when you turn the vacuum off you're subjecting those devices to a surge. After vacuum cleaners, the next biggest source of surges would have to be fans (both those plugged into the wall and ceiling fans).

Now that we know the sources of surges, what can we do about it? Obvious you say, we use a surge protector. Well yes and no. The answer is a surge protector, but not all surge protectors are created equal. Most people refer to the following item as a surge protector:

This may be a surge protector, but chances are good it's just a power strip. A power strip is nothing more than multiple outlets with an on/off switch. It offers zero protection against over-voltage or over-current. A true surge protector is usually a little larger in size and costs more. The only way to tell them apart is to either open them up and look on the inside, or read the specs that came with the product. Chances are if you spent less than $10 or $20 on it, then it's probably a power strip not a surge protector. Probably the most respected name is APC, they make high-quality devices. There are other good brands as well.

Even if you have good-quality surge protectors, you may not be covered. As it turns out surge protectors breakdown over time. In effect they can only protect against a certain number of surges before they fail. When they fail the surge protector will still provide power, but the surge protection aspect is gone.

So what's the take-away from all this.

1. Identify the circuits on your house with expensive electronic items (TVs, computers, etc.). Never use a vacuum cleaner on these circuits. Also, if possible avoid fans on these circuits.
   
2. Buy and use good quality surge protectors NOT power strips.
   
3. Even if you have good-quality surge protectors, don't assume you're safe as they have a limited lifespan.
   

If you really want to know more on this, I recommend you watch this video in which he does a great job of explaining inductive spikes. Also, the following article dissects a surge protector and goes into more details.

Electronic parts

Lately I've been doing a lot of electronics repair. It's kind of a fun little hobby. Say your flat-panel computer monitor dies on you. You could throw it away, or for about $4 and 5 minutes of time you can repair it. Of course, you need to know how and what to repair, and I'm not really going to cover that here. The other thing you need is replacement parts, which is what I wanted to talk about today.

Say you need a diode, capacitor, resistor, etc. to repair an item. You could go down to your local Radio Shack or other electronics supply shop, but I would recommend against it. First, these places have a very limited supply, and second if you buy online you can get higher quality components. Also, the prices online are cheaper, although when you add in shipping the final cost will be about the same.

I recommend digikey.com. There are other sites, but digikey is my preferred supplier. Let's say you're looking for a 680 uF 16 volt capacitor (like this):

Knowing how to find this on digikey's site can be overwhelming the first time you try it.

1. Enter "capacitor" in the search box on digikey's site and hit enter.
   
2. The next screen shows all the different type of capactitors (e.g. ceramic, tantalum, etc.). In this case we're looking for "aluminum" so click on that. (BTW: you just need to learn that aluminum is another name for standard electrolytic capacitors.)
   
3. On the next screen, you need to filter down the selection. Under capacitance select "680uF." Under voltage select "16V." Under mounting type select "through hole." Finally check "in stock" and click Apply Filters.
   
4. This filtered it down to 17 choices. From here you can find the one you want, or further filter using manufacture, dimensions, etc.
   

Depending on which one you select, the capacitor is only .40 - .75 plus shipping (which is cheap for small orders). Once you learn to navigate digikey's site they have some really cool stuff such as thousands of LEDs of ever shape and color. If you're into electronics repair, hobby kit building, RC planes/cars, etc. give digikey a look, they are very useful.