Socketing BIOS and Maria chips...

[shadow460]

I've got a DevOS kit on the way, and installing it into my thrid generation 7800 is going to mean desoldering. I read Bruce's FAQ on desoldering, and I knew exactly which iron/bulb combo he mentioned. I got one.

My first project was to attempt desoldering the AMD (yes, AMD) rom chip from a dead Beany Bopper cart. That was unsuccessful since I'd messed up trying to save the cart.

So I grabbed my mislabeled "duck hunt" cartridge (it's NES Baseball) and went after the lockout chip.

I got it out. However, I noticed it was pretty warm while I was desoldering it. since my NES has its internal lockout chip disabled, I won't know if the Baseball game's lockout chip has died by running it in the NES.

 

Here are the questions I have:

First and foremost, the dumbest one:

How do I identify the Maria and BIOS chips?

I think I can pick them out (the largest 48 pin chip on the board is maria, IIRC) but I want to be certain.

 

Second: How long do I leave the desoldering iron on the pins?

Bruce's FAQ says 4 to 5 seconds after the solder melts, but that wasn't pulling everything off the Beany Bopper ROM.

 

Third (and most important):

Can the Maria withstand heat, and how much? My desoldering iron is 45 watts. I could mount the desoldering part to any Radio Shack iron, including the 15 watt grounded iron I'm thinking of buying to replace my old one.

What's the best way to dissipate heat from the Maria while desoldering it? Or do I need to do one pin at a time and wait a couple minutes in between pins?

 

See, I'm not real concerned if I fry the BIOS. I'd like to keep it functional, sure, but the DevOS BIOS will run my console. But if I fry the Maria, the console's dead until I get a new one, and I don't want to go through all that.

 

That brings me to my last question:

If I do totally goof up the Maria chip, where would I obtain a new one?

[PacMan]

If you fry MARIA Best Electronics has them.

 

I never liked the idea of desoldering pin for pin so I created a a desoldering tool with a copper plate bent to touch all the pins at the same time and mounted it on a 75W soldering iron. When I remove DIP IC's I simply fasten the board in a holder that holds it in an upright position, put the new "solder tip" on the pins for 4-5 seconds and pull the IC out. Works everytime an I have not managed to destroy any chip or board yet.

 

/P

[gdement]

If you fry MARIA Best Electronics has them.

 

I never liked the idea of desoldering pin for pin so I created a a desoldering tool with a copper plate bent to touch all the pins at the same time and mounted it on a 75W soldering iron. When I remove DIP IC's I simply fasten the board in a holder that holds it in an upright position, put the new "solder tip" on the pins for 4-5 seconds and pull the IC out. Works everytime an I have not managed to destroy any chip or board yet.

 

/P

 

That's awesome. I've often wished I had a tool like that. Desoldering pin by pin is too hard.

===

 

The MARIA chip should be labelled GCC-1702, although I don't have one exposed to check with. I suppose if you're worried, you might consider attaching a heatsink to it. Might be a good idea anyway for the chip's longevity, as it's the most high-strung chip in the machine, and it's not an off-the-shelf part. I think there's a version of Arctic Silver that works as a (permanent) adhesive.

[Bruce Tomlin]

If you fry MARIA Best Electronics has them.

 

I never liked the idea of desoldering pin for pin so I created a a desoldering tool with a copper plate bent to touch all the pins at the same time and mounted it on a 75W soldering iron. When I remove DIP IC's I simply fasten the board in a holder that holds it in an upright position, put the new "solder tip" on the pins for 4-5 seconds and pull the IC out. Works everytime an I have not managed to destroy any chip or board yet.

 

/P

 

That's awesome. I've often wished I had a tool like that. Desoldering pin by pin is too hard.

I do it all the time. It's very Zen. But it really does take a lot of practice. I think they do make real tips like that, but I guess you really would need a higher wattage (or temperature controlled) soldering iron to make it work. The idea of just being a hunk of copper is a good one, though.

 

One technique I've only recently learned is to wiggle the pin with the soldering iron, and when I can hear it squeak, I know it's ready to suck the solder.

 

If you're worried about overheating pins (which I think is overrated anyhow), then only do every other pin, or one corner at a time.

 

And really, most of the pins go with about two seconds of heat, it's the ground and +5V pins that are the big problems because of the larger pads sucking away the heat. Check to see how much has worked its way up the legs of the chips on the top side. Another trick I've used when desoldering big capacigtors from old power supply boards (just for the fun of it, of course) is to stick another soldering iron in the same area to add heat. Since the other iron is termperature controlled, I crank it up to 700F instead of my usual 600F.

 

No matter what, though, with that Radio Shack desoldering iron, a new tip gives best results.

[+Allan]

If you fry MARIA Best Electronics has them.

 

I never liked the idea of desoldering pin for pin so I created a a desoldering tool with a copper plate bent to touch all the pins at the same time and mounted it on a 75W soldering iron. When I remove DIP IC's I simply fasten the board in a holder that holds it in an upright position, put the new "solder tip" on the pins for 4-5 seconds and pull the IC out. Works everytime an I have not managed to destroy any chip or board yet.

 

/P

 

That's awesome. I've often wished I had a tool like that. Desoldering pin by pin is too hard.

I do it all the time. It's very Zen. But it really does take a lot of practice. I think they do make real tips like that, but I guess you really would need a higher wattage (or temperature controlled) soldering iron to make it work. The idea of just being a hunk of copper is a good one, though.

 

One technique I've only recently learned is to wiggle the pin with the soldering iron, and when I can hear it squeak, I know it's ready to suck the solder.

 

If you're worried about overheating pins (which I think is overrated anyhow), then only do every other pin, or one corner at a time.

 

And really, most of the pins go with about two seconds of heat, it's the ground and +5V pins that are the big problems because of the larger pads sucking away the heat. Check to see how much has worked its way up the legs of the chips on the top side. Another trick I've used when desoldering big capacigtors from old power supply boards (just for the fun of it, of course) is to stick another soldering iron in the same area to add heat. Since the other iron is termperature controlled, I crank it up to 700F instead of my usual 600F.

 

No matter what, though, with that Radio Shack desoldering iron, a new tip gives best results.

 

I just unsoldered my Maria chip with the Radio Shack desoldering tool. It really is pretty easy with a little practice, even witha big chip like Maria.

 

Allan

[shadow460]

"a new tip gives best results"

I checked prices on new tips--$1.49. I'm not risking my console in trying to re use one, but I probably will use the same tip for more practice.

I'm also thinking about replacing the 15 watt iron I'll use to mount the sockets...the tip is seized into the iron shaft and you can only guess how worn out the tip is... A new one is less than the desoldering iron.

The desolderin iron, BTW, runs at about 450 degrees (accroding to the package).

I thought about heatsinking the Maria anyway. I've used Arctic Silver thermal adhesive before. The video card I used it on is still in service today, and the heatsinks haven't even budged.

I used Artic Silver adhesive on the GPUs' heatsinks and a combination of cyanoacrylate and Artic Silver 5 on the RAM sinks. I'll probably go with the glue/AS9 mix if I do heatsink the Maria.

Problem is, the XBoarD is going to raise up the Maria some, so I'd need to find a heatsink that would still fit under the RF shield...unless I could somehow attatch it to the RF shield.

 

That's off the subject. For a temporary cooling solution, perhaps a small table fan would work.

 

Hey, PacMan, you should try marketing those copper tips. I bet you could make a small fortune.

Edited October 14, 2006 by shadow460

[shadow460]

Bump. I just recieved the Dev OS kit today from jaybird3rd. He sent three 24 pin sockets.

So I started desoldering away...and realized too late I was desoldering the CPU! I re soldered it without sockets (although maybe I shoulda got two 20 pin sockets for it) and worked the Maria out. It took a while, but it was actually pretty easy. I worked three pins at a time, alternating corners and taking a break every once in a while to let Maria cool down and (mainly) to let my hands rest. Getting Maria into the sockets, however, is a bit of a chore with 48 pins, but I did it. Note to self: Straighten IC pins before insterting into socket.

I tested the system with Pole Position II, knowing there's one of those for sale nearby if my cart fried somehow. Everything was good. Next test was Cosmic Ark--also good, though it doesn't need Maria.

 

Next was the BIOS chip. I got it desoldered fine, but ripped a trace off the board from pin 24 when I pulled the Atari BIOS. The trace stayed attatched to the board on one end, and popped with the BIOS chip on the other. I crammed it back into the hole and soldered the 24 pin socket down without the wrapping wire. I tested the socket with the original BIOS and those two games. Everything was fine.

The next step was the inverter chip and the EPROM mod. The FAQ I used was one of Bruce's, but it looked like there was a typo. I think he meant to say "solder pins 1, 7, and 14. Now bend up Pin 8." The 14 was left out. I grabbed a datasheet for the inverter and saw that Pin 14 is Vcc. things work better when you plug them in, so I soldered 14. I ran the wire from Pin 2 around the motherboard and to the bottom side of the BIOS socket. It runs by the center screw post, which I managed to break on disassembly. It's about 12 inches long--more than I'd like, but it seems to work ok.

Next step was to plug in the DevOS BIOS and test everything. Once again, it worked on both games.

 

The final mod that I had parts for was a TV Type switch. I cut a hole under the horizontal part on the left side of my mint console and stuck a toggle switch through. I wired that across the Pause switch contacts. The next test featured 01 combat instead of the other two games. The TV Type switch works as planned.

 

I have not yet tested the RAM cart or the cable. Jay tested them before shipping.

I've got to say I'm very impressed with what I recieved in the mail. It looked like it came straight from the factory--everything was well packed, and there wasn't a speck of dust or dirt indicating it had been just lying around somewhere.

 

Thanks to Jay, Bruce, and everyone who contributed here. Now it's time for me to start writing games!

[jaybird3rd]

Glad to hear everything arrived safely!

 

You should find a copy of the BallBlazer ROM on the disk I included (you're certainly entitled to have that since your RAM cart was originally a BallBlazer game), and you can use that or any other 16K/32K game for testing the cartridge and cable. Definitely let me know if you have any problems.

Edited October 26, 2006 by jaybird3rd

[shadow460]

lol, I own one silver and one CIB red label Ballblazer, so I've got the copyrights covered. I would like to make a label for the RAM cart, though, stating that it's a 32K Pokey cart.

Oddly, it won't load the Ballblazer ROM. It loaded the final demo of Beef Drop. Ballblazer is an a78 file, and Beef Drop is a bin file, so I assumed that's what it was. I noticed several different switches could be used on the command line--I assume those are for bankswitching routines.

 

Does it load 2600 games, too?

[+Mitch]

You need to load BIN files, A78 files won't work unless you strip off the header. Most non-bankswitched 2600 games should work as well.

 

Mitch

[shadow460]

Makes sense.

[jaybird3rd]

You need to load BIN files, A78 files won't work unless you strip off the header. Most non-bankswitched 2600 games should work as well.

That's funny, loading .A78 files has always worked for me. I generally use the following command-line options, if they're helpful:

 

7800CTRL -l1 -f BALLBLZR.A78

I just tried this successfully on my system with BallBlazer, Robotron, and Ms. Pac-Man (all A78 files). I haven't had any luck loading 2600 binaries using that particular POKEY RAM cartridge design, but since it's meant primarily for 7800 development I haven't cared too much. I'm sure a regular, non-POKEY RAM cart would be 2600-compatible, though.

Edited October 27, 2006 by jaybird3rd

[supercat]

I checked prices on new tips--$1.49. I'm not risking my console in trying to re use one, but I probably will use the same tip for more practice.

 

It may also be a good idea to make sure the 7800 is completely disconnected from everything else. I once saw a piece of video equipment destroyed (trace blasted off board) because a Radio Shack soldering tool developed a short from the heating element to the tip. The video equipment had its power disconnected, but the video output was connected to a grounded display. Fortunately the display was undamaged, but blasted traces are still not fun.

 

Related note: on a different project, a PIC 16C73 processor was connected to a pot via 1K resistor. A nearby 110 volt wire slipped and touched the pot. The 1K resistor exploded, but the PIC was undamaged. Those old PICs sure were hardy devices.

[shadow460]

I had the motherboard on my table. What I think happened was that some solder ran through to the top and cooled there while I was cracing the other pins loose.

That made me think twice about socketing anything that did not really need it. Since I'd partially desoldered Sally, I thought about socketing her, but I don't see a reason to. As for shorts, my desoldering iron is brand new, and my regular iron is grounded. It'll kill the power if it shorts, it doesn't develop static electricity, and it works with a marine electrical system (that's the main reason I got a grounded iron).

Edited October 27, 2006 by shadow460

[+Mitch]

You need to load BIN files, A78 files won't work unless you strip off the header. Most non-bankswitched 2600 games should work as well.

That's funny, loading .A78 files has always worked for me. I generally use the following command-line options, if they're helpful:

 

7800CTRL -l1 -f BALLBLZR.A78

I just tried this successfully on my system with BallBlazer, Robotron, and Ms. Pac-Man (all A78 files). I haven't had any luck loading 2600 binaries using that particular POKEY RAM cartridge design, but since it's meant primarily for 7800 development I haven't cared too much. I'm sure a regular, non-POKEY RAM cart would be 2600-compatible, though.

 

 

Hmm, you could be right about the A78 files, it's been a while since I've used the RAM cart part of it.

I know I had 2600 games running on mine but I never tried the 32K RAM cart, only the 48K and 144K versions.

 

Mitch

[Bruce Tomlin]

The next step was the inverter chip and the EPROM mod. The FAQ I used was one of Bruce's, but it looked like there was a typo. I think he meant to say "solder pins 1, 7, and 14. Now bend up Pin 8." The 14 was left out.

 

Huh? It was there in my copy:

 

http://xi6.com/hacks/7800eprom.html

 

I vaguely remember that it got left out when I originally wrote it, and someone probably put up that version somewhere.

[shadow460]

The next step was the inverter chip and the EPROM mod. The FAQ I used was one of Bruce's, but it looked like there was a typo. I think he meant to say "solder pins 1, 7, and 14. Now bend up Pin 8." The 14 was left out.

 

Huh? It was there in my copy:

 

http://xi6.com/hacks/7800eprom.html

 

I vaguely remember that it got left out when I originally wrote it, and someone probably put up that version somewhere.

 

I got my copy from the DevOS website. Could be that someone had the file open and somehow removed the note about Pin 14. It's easy to figure out, though--since the guide says to leave pin 14 unfolded, it just amkes sense that one should find out if it needs to be soldered in. All you gotta do from there is Google the IC, and it tells you that 14 is Vcc. No power, no IC function, so we know to solder it down.

[Bruce Tomlin]

I got my copy from the DevOS website. Could be that someone had the file open and somehow removed the note about Pin 14.

I told you I remembered it being missing when I first wrote it, then I fixed it.

[shadow460]

My bad.

[Lynxpro]

That's awesome. I've often wished I had a tool like that. Desoldering pin by pin is too hard.

===

 

The MARIA chip should be labelled GCC-1702, although I don't have one exposed to check with. I suppose if you're worried, you might consider attaching a heatsink to it. Might be a good idea anyway for the chip's longevity, as it's the most high-strung chip in the machine, and it's not an off-the-shelf part. I think there's a version of Arctic Silver that works as a (permanent) adhesive.

 

 

I know this is an old post to reply to, but does anyone have a pic of a heat sink attached to the Maria chip? Any suggestions on the best process for doing this? And has anyone ever installed a mini fan [like, say, the same type of case fan that the Atari Falcon has] inside their 7800? Thanks.

[ApolloBoy]

I know this is an old post to reply to, but does anyone have a pic of a heat sink attached to the Maria chip?

The MARIA chip never had a heat sink and it doesn't get hot enough to need one anyway. There's no point in installing a fan either when there's nowhere near enough heat buildup to warrant one.

[Lynxpro]

The MARIA chip never had a heat sink and it doesn't get hot enough to need one anyway. There's no point in installing a fan either when there's nowhere near enough heat buildup to warrant one.

 

 

I never said the 7800 came stock with a heat sink for the MARIA chip. However, from my experiences, the MARIA chip does get hot and merits a heat sink mod. My own 7800 - and my grandmother's 7800 - would become hot when playing Xevious or Desert Falcon for a decent amount of time and it was due to the MARIA chip. It's been a popular topic regarding the 7800 for years elsewhere on the net so yeah, it is of interest. As such, I'd love to see a pic from anyone that's ever modded the 7800 with a heat sink attached to the MARIA chip. A case fan would also be cool to see.

[Trebor]

It's been a popular topic regarding the 7800 for years elsewhere on the net so yeah, it is of interest.

 

I've been following the Atari scene online, especially the 7800, since the mid 90's and this is the first time I've read of anyone mentioning the heat of the MARIA chip.

 

I would love to read about this; besides this topic, a Goggle search yields nothing. Do you have links you could please post? Thanks.

[Lynxpro]

I've been following the Atari scene online, especially the 7800, since the mid 90's and this is the first time I've read of anyone mentioning the heat of the MARIA chip.

 

I would love to read about this; besides this topic, a Goggle search yields nothing. Do you have links you could please post? Thanks.

 

 

http://atariage.com/manual_html_page.html?SoftwareID=2357

 

 

"Problem: If I play for an extended period of time the Atari 7800 PROsystem console

will sometimes lock up and I can’t play anymore until I power off then back on.

Remedy: There is an overheat/lockup problem with the MARIA graphics processor

chip in the Atari 7800 PROsystem consoles which can cause this problem to occur, there

is no remedy to fix this problem."

 

Both of "my" 7800s were purchased back in 1986...my grandmother's was purchased around May/June of that year and my own personal one later in December of that year. This was before Atari Corp. removed the Expansion Port from later revisions [so I don't know personally if the heat issue persisted in the later revisions]. All one would have to do was play a sprite/missile-intense game - such as Xevious or Desert Falcon - for a couple of hours and the 7800's MARIA chip would cause the console to get very hot [and sometimes the games would lock up].

 

I can't explain why Google doesn't find a lot of links on the issue; it was certainly well-known back in the Atari BBS days.

[Trebor]

http://atariage.com/...SoftwareID=2357

 

 

"Problem: If I play for an extended period of time the Atari 7800 PROsystem console

will sometimes lock up and I can’t play anymore until I power off then back on.

Remedy: There is an overheat/lockup problem with the MARIA graphics processor

chip in the Atari 7800 PROsystem consoles which can cause this problem to occur, there

is no remedy to fix this problem."

 

Both of "my" 7800s were purchased back in 1986...my grandmother's was purchased around May/June of that year and my own personal one later in December of that year. This was before Atari Corp. removed the Expansion Port from later revisions [so I don't know personally if the heat issue persisted in the later revisions]. All one would have to do was play a sprite/missile-intense game - such as Xevious or Desert Falcon - for a couple of hours and the 7800's MARIA chip would cause the console to get very hot [and sometimes the games would lock up].

 

I can't explain why Google doesn't find a lot of links on the issue; it was certainly well-known back in the Atari BBS days.

 

Awesome! Thank you. I've read that doc before and didn't recall ever seeing that. I've never personally experienced the issue (Then again, never played a couple of hours worth of Xevious or Desert Falcon) - looks like your heat sink or/and fan idea is definitely something needed for systems that experience the problem.