matthew180 Posted January 21, 2011 Share Posted January 21, 2011 I'm fixing an MBX system for a fellow TIer and I need a new internal speaker. The problem is, I don't have the original, and neither does the owner of the unit. I'd like to get as close a replacement as possible, and there is a sort of "bracket" that holds the speaker (or appears to anyway.) If anyone has an MBX that they would not mind opening up, I would greatly appreciate some detail photos of the speaker, how it is mounted, and a few basic measurements of the speaker itself. All you should have to do is remove the screws from the bottom and take off the top. The speaker will be sitting right there. **WARNING** You have to take the screws out of the bottom, then turn the unit back over so it is sitting normally, then lift the top off. If you do not, you risk breaking off the internal voltage regulator!! It is a really bad design, but if you open it as I described, you should not have any problem. Thanks, Matthew Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted January 22, 2011 Share Posted January 22, 2011 I own an MBX, so if nobody else has already done so, I'll open mine up and take some pictures. I've been looking for an excuse to open it up anyway. Quote Link to comment Share on other sites More sharing options...
matthew180 Posted January 22, 2011 Author Share Posted January 22, 2011 If you don't mind, I'd really appreciate it. Like I mentioned above, just make sure you have the thing right-side-up when you take the two halves apart. The reason for this is because of a *really* bad case design where the main voltage regulator and heat sink are screwed to the bottom section, but the circuit board is only held in place by the two halves of the shell. If you try to take it apart up-side-down, when you start lifting the bottom section, the circuit board's weight will bend the legs on the regulator and you can easily break it off. You can see a nice picture or the MBX open on Ron's site: http://www.mainbyte.com/ti99/hardware/mbx/mbx.html Unfortunately I cannot see the details of the speaker in the pictures on his site, and those are the only pictures I have found of the inside of the MBX. Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted January 22, 2011 Share Posted January 22, 2011 Yes, there doesn't seem to be much information out there about the MBX. Pictures and detailed technical information are both very scarce. I'd still love to know how to program for it: as I mentioned in the thread I linked to above, it would be fun to be able to add MBX support to homebrew 99/4A games. I'll try to bring it out and open it up tomorrow afternoon. Quote Link to comment Share on other sites More sharing options...
+acadiel Posted January 22, 2011 Share Posted January 22, 2011 While we're at it, can anyone measure the ID and OD of the DC jack? I need a new one but don't know what ID and OD to order from Mouser.... Thanks Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted January 22, 2011 Share Posted January 22, 2011 While we're at it, can anyone measure the ID and OD of the DC jack? I need a new one but don't know what ID and OD to order from Mouser... I'll take some measurements of the jack also. Quote Link to comment Share on other sites More sharing options...
matthew180 Posted January 22, 2011 Author Share Posted January 22, 2011 The power *PLUG* (the part connected to the power cord) is a standard 5.5mm(OD) x 2.1mm(ID) positive tip (inside is positive). Quote Link to comment Share on other sites More sharing options...
+acadiel Posted January 22, 2011 Share Posted January 22, 2011 The power *PLUG* (the part connected to the power cord) is a standard 5.5mm(OD) x 2.1mm(ID) positive tip (inside is positive). That helps me out. I'll buy a new jack (yes, the jack inside the unit is broken) from Mouser that's 5.5mm (OD) and 2.1mm (ID). Thanks, Matthew!! Quote Link to comment Share on other sites More sharing options...
matthew180 Posted January 22, 2011 Author Share Posted January 22, 2011 Well, if you are buying a jack for the MBX board, you should probably be more concerned with the physical pin out for the jack on the board itself. My suggestion would be to find a jack that matches the board, then see if you can get one that is 5.5mm x 2.1mm Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted January 22, 2011 Share Posted January 22, 2011 Okay, here are some pictures of the speaker inside the MBX: I forgot to take measurements while I had the MBX open, but it looks to me like a standard 2.25-inch magnetic driven speaker (the same size that was used inside old PC cases for the built-in speaker). The "side view" picture might be a little unclear, but the plastic clips snap over the speaker's magnetic ring to hold the speaker in place. Hope this helps, and let me know if you need anything else. Quote Link to comment Share on other sites More sharing options...
matthew180 Posted January 22, 2011 Author Share Posted January 22, 2011 Perfect! That's quite a speaker!! Much bigger than the ones I was looking at, and it makes the mounting clips much more clear, thanks! Now I need to see if I can find such a beast. The only measurement I could really use is the over all diameter. Oh, it also explains why the MSX uses a dedicated audio amp for the internal speaker too. Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted January 22, 2011 Share Posted January 22, 2011 I'll be out tonight, but I'll open it up again--and take some measurements this time!--when I get back. I'll measure the diameter of the speaker as well as the base (including the magnet). Quote Link to comment Share on other sites More sharing options...
matthew180 Posted January 23, 2011 Author Share Posted January 23, 2011 Cool, thanks! I think I found a perfect replacement: http://www.mouser.com/Search/ProductDetail.aspx?R=25RF123virtualkey12800000virtualkey25RF123 8Ohms, 0.7Watts, 3.5KHz frequency range, exactly matches the LM386 audio amp, and has the physical specs to fit in the clip (including needing the foam pad on the bottom!!) Quote Link to comment Share on other sites More sharing options...
+acadiel Posted May 30, 2011 Share Posted May 30, 2011 The power *PLUG* (the part connected to the power cord) is a standard 5.5mm(OD) x 2.1mm(ID) positive tip (inside is positive). That helps me out. I'll buy a new jack (yes, the jack inside the unit is broken) from Mouser that's 5.5mm (OD) and 2.1mm (ID). Thanks, Matthew!! Just FYI, I finally got around to ordering a replacement jack. Mouser URL Datasheet I'll let you know how it works out.. pinout looks identical, but I don't have a micrometer handy, so the spacing might be off. Stay tuned. Quote Link to comment Share on other sites More sharing options...
+acadiel Posted June 3, 2011 Share Posted June 3, 2011 (edited) Just FYI, I finally got around to ordering a replacement jack. Mouser URL Datasheet I'll let you know how it works out.. pinout looks identical, but I don't have a micrometer handy, so the spacing might be off. Stay tuned. Got the replacement jack in from Mouser. The through hole pattern and jack size was spot on. However, the through pins were a little large for the hole in the MBX PCB. Nothing a 3/32" drill wouldn't fix. A quick desolder job, followed by the drill, and then the soldering of the new jack seems to have worked great. I have a spare now too, since they were so cheap (I do have a second MBX somewhere in a box.) I also had to take a cm or so off of the ribbon cable that comes from the keypad matrix on the front of the MBX with some scissors. The contacts weren't making great contact with the board once inserted, even after a good pencil erasing. Still have plenty of slack. The only other thing that I might wind up having to do to get this thing completely working (100%) is make a new cable for it - I think there's a short in one of the DB9 connectors. For right now, the kids are playing "I'm Hiding" again and are ecstatic that it's working properly for once!! I suppose it's time to play with the hybrid GROM/ROM cartridge board now.... :-) Tursi, I'll burn another flash chip and make sure it works and see what happens on the board again. Jon Edited June 3, 2011 by acadiel Quote Link to comment Share on other sites More sharing options...
+retroclouds Posted June 4, 2011 Share Posted June 4, 2011 I suppose it's time to play with the hybrid GROM/ROM cartridge board now.... :-) Tursi, I'll burn another flash chip and make sure it works and see what happens on the board again. Jon Pictures please! Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted June 6, 2011 Share Posted June 6, 2011 Got the replacement jack in from Mouser. The through hole pattern and jack size was spot on. However, the through pins were a little large for the hole in the MBX PCB. Nothing a 3/32" drill wouldn't fix. A quick desolder job, followed by the drill, and then the soldering of the new jack seems to have worked great. I have a spare now too, since they were so cheap (I do have a second MBX somewhere in a box.) That's great news! Thanks for posting the link; I'll have to pick up a few spares myself. This reminds me ... I never cracked open my MBX again to dump its ROM, as I said I would in another thread. I'll have to remember to do this when I get my 99/4A stuff out of storage again later this month. Quote Link to comment Share on other sites More sharing options...
blackbox Posted October 30, 2017 Share Posted October 30, 2017 Yes, there doesn't seem to be much information out there about the MBX. Pictures and detailed technical information are both very scarce. I'd still love to know how to program for it: as I mentioned in the thread I linked to above, it would be fun to be able to add MBX support to homebrew 99/4A games. I'll try to bring it out and open it up tomorrow afternoon. Check out post 15 on this thread: http://atariage.com/forums/topic/172843-the-mbx-expansion-system/ to see the work Barry Boone did to enable programmers in Extended Basic to use the facilities of the MBX Games Unit. Never forget: Only plug the MBX unit into your consoe when the console is powered off. It is not hot pluggable. regards Stephen Quote Link to comment Share on other sites More sharing options...
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