Shift838 Posted August 24, 2016 Share Posted August 24, 2016 I think I read somewhere that someone powered a NanoPEB/CF7+ with their 99/4A Composite video port. The Nano/CF7+ requires a 5v DC current to be supplied. The question I have is I believe Pin #1 supplies a 12v current if I recall correctly (someone correct me if I am wrong or verify if I'm right) So based on what I found on the web a 1.5k resistor would pull the 12v down to 5v. If so then we should be able to hook up pin 1 and pin #2 (for TI-99/4A US model) and power the Nano via a couple of wires, resistor and power plug connector. Or am I completely wrong? If this is correct, then.. Another question: If someone has the F18A video upgrade, would the above still work? I'm just thinking of how I can remove a plug from my power strip. Quote Link to comment Share on other sites More sharing options...
+jedimatt42 Posted August 24, 2016 Share Posted August 24, 2016 I think you would be better off with a 7805 voltage regulator. I'm just learning, but to my knowledge resisters lower current, not voltage. However, there are techniques for creating voltage splitters from a pair of resistors. But i don't yet understand the theory behind that. -M@ 1 Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted August 24, 2016 Share Posted August 24, 2016 . hi, cool idea, if this is possible. And I remember a post about taking the power from the speech synthie. Here just some infos on the video port I was gathering for my Geneve-cable, including some facts for the TI-99 (no warranties ) GENEVE-9640-PINOUT-Voltage-008-Bin.pdf Quote Link to comment Share on other sites More sharing options...
Stuart Posted August 24, 2016 Share Posted August 24, 2016 A resistor would drop the voltage but it's a very bad idea for this application. The voltage (in Volts) across the resistor = the current going through it (in Amps) * the resistance (in Ohms). The problem here though is that the current drawn by the NanoPEB won't be constant - it will probably increase when you read/write to the card for example, so the voltage dropped across the resistor won't be constant, and so the voltage you're supplying the NanoPEB with will vary. Whether it will go high enough to damage it or low enough for it not to work, I'm not sure. You'd probably also need a fairly high power (Wattage) resistor to drop enough voltage and supply enough current. A 7805 voltage regulator is what you'd need here. (Using a pair of resistors as a voltage splitter to generate a reference voltage is fine as long as you're pulling a very low current.) What I've done for my nanoPEB is to solder a cable with connector direct onto the internal PSU output, and feed it out through the side port slot. To do this you'd need to be able to solder the cable together, and have a multimeter to verify you've got the voltage and polarity right before you connect it to the nanoPEB. 3 Quote Link to comment Share on other sites More sharing options...
RickyDean Posted August 24, 2016 Share Posted August 24, 2016 I am going to try one of the TRACO dc/dc converters and see if that works ok on my CF7+'s. I bought 5 from Mouser to use one on my SAMS and Corcomp. Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted August 24, 2016 Share Posted August 24, 2016 I was just thinking that. I have seen some DC-DC chips which would fit in a DIN plug. Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted August 24, 2016 Share Posted August 24, 2016 I believe there is +5 V on each of lands 1 and 2 of the side port. The only problem is that neither is passed through in the speech synthesizer. It might also be difficult to make the connection from one of those lands on the nanoPEB/CF7+. ...lee Quote Link to comment Share on other sites More sharing options...
Shift838 Posted August 24, 2016 Author Share Posted August 24, 2016 . hi, cool idea, if this is possible. And I remember a post about taking the power from the speech synthie. Here just some infos on the video port I was gathering for my Geneve-cable, including some facts for the TI-99 (no warranties ) GENEVE-9640-PINOUT-Voltage-008-Bin.pdf That's what I was remember, not the composite port, but the speech port. I think the power on the speech port is already 5v correct? 1 Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted August 24, 2016 Share Posted August 24, 2016 (edited) I think so. Ciro from TI IUC had some infos on that mod, IIRC. see below Edited August 24, 2016 by schmitzi Quote Link to comment Share on other sites More sharing options...
Omega-TI Posted August 24, 2016 Share Posted August 24, 2016 You could still tap off that power internally and add one of these inexpensive devices... Then add one of these on the right hand side of the TI << CLICK HERE >> Assembled and ready to use power regulator << CLICK HERE >> for jack. 1 Quote Link to comment Share on other sites More sharing options...
Shift838 Posted August 24, 2016 Author Share Posted August 24, 2016 (edited) this looks like a cool option and with the size i am sure there is a spot to hide this in the console! might even be easier than tapping into the speech synth port. And a plus is those type of jacks work great to pull the audio signal off too! Edited August 24, 2016 by Shift838 Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted August 24, 2016 Share Posted August 24, 2016 uuuh I found it, was from Sparkdrummer: 5 Volts stolen from speech http://atariage.com/forums/topic/247666-cf7-power-supply/?p=3414821 Quote Link to comment Share on other sites More sharing options...
ti99iuc Posted August 24, 2016 Share Posted August 24, 2016 (edited) might even be easier than tapping into the speech synth port. And a plus is those type of jacks work great to pull the audio signal off too! uuuh I found it, was from Sparkdrummer: 5 Volts stolen from speech http://atariage.com/forums/topic/247666-cf7-power-supply/?p=3414821 Yes, indeed this is the right person not me i also suggest to read again this thread by our friend Dexter... Btw... i remember that Dexter had health problems, now he is not so present here... who has some news please ? http://atariage.com/forums/topic/238047-a-few-random-mods-for-the-ti-994a-to-get-rid-of-some-annoyances/?p=3233433 Edited August 24, 2016 by ti99iuc Quote Link to comment Share on other sites More sharing options...
Shift838 Posted August 24, 2016 Author Share Posted August 24, 2016 thanks guys. i'll reach out to him. Quote Link to comment Share on other sites More sharing options...
Shift838 Posted August 24, 2016 Author Share Posted August 24, 2016 i ordered the parts that OHM recommended and I will give it a shot when they get here and update the thread. 1 Quote Link to comment Share on other sites More sharing options...
unhuman Posted August 25, 2016 Share Posted August 25, 2016 I've always wanted to replace the internal power supply with something else... That sucker makes so much heat... So many lockups. Quote Link to comment Share on other sites More sharing options...
Stuart Posted August 25, 2016 Share Posted August 25, 2016 this looks like a cool option and with the size i am sure there is a spot to hide this in the console! But if you're going to fit it inside the console, what's the point of using a 12V>5V regulator when you could just tap into the existing 5V supply directly? Quote Link to comment Share on other sites More sharing options...
Shift838 Posted August 25, 2016 Author Share Posted August 25, 2016 But if you're going to fit it inside the console, what's the point of using a 12V>5V regulator when you could just tap into the existing 5V supply directly? originally the post was about using the 12v line on the composite jack as I remembered wrong and it was the speech 5v line that was shared. But this became an interesting topic. We could just tie into the 5v lines of the TI for inside the console. Now I just need to figure out where the 5v line is in the console. (hint if you like or just plain tell me!) Omega had a great idea of using a USB jack so you could even charge a smartphone! Quote Link to comment Share on other sites More sharing options...
Omega-TI Posted August 25, 2016 Share Posted August 25, 2016 How many mA reserve does the 5V board have to spare before it draws too much current, heats up, or causes weird stuff to happen? I dunno. I thought the reason he wanted to go this route is because besides the normal load, he is also powering a USB keyboard adapter in addition to the speech synthesizer. By stepping down from the 12V line he would be reducing the load on the internal 35 year old internal assembly. I'm not sure what the design limitations are, but why risk stressing or ruining a hard to replace item? As for the USB jack... it's on my future list. Quote Link to comment Share on other sites More sharing options...
Stuart Posted August 26, 2016 Share Posted August 26, 2016 Now I just need to figure out where the 5v line is in the console. (hint if you like or just plain tell me!) Omega had a great idea of using a USB jack so you could even charge a smartphone! If you open the case and remove the PSU board, I'm pretty sure that the pins that the motherboard power cable plugs onto are labelled on the component side - should be +12V, +5V, -5V and GND. Don't know off-hand what the order of the pins is though as I'm away from home at the moment and don't have a spare power supply to look at. You should be able to solder a new cable onto the back of the relevant pins. I'll stress again - you need a (cheap)voltmeter to confirm that you've got the cable and power connector round the right way before you plug in into the nanoPEB - if you've got the polarity reversed then you'll be looking for a new nanoPEB. Bad idea trying to charge a smartphone. A USB port should be able to supply 500mA. That's half as much again as the motherboard draws (~950mA) and may well damage the power supply or transformer. Quote Link to comment Share on other sites More sharing options...
Tursi Posted August 26, 2016 Share Posted August 26, 2016 Measure voltages before you unhook the power supply for replacement. I have at least one PCB that has the labels incorrect. Quote Link to comment Share on other sites More sharing options...
+arcadeshopper Posted August 26, 2016 Share Posted August 26, 2016 the +5v is on one side as you can see here: easy to identify and on the back side of the board easy to solder a jumper to those two pins giving you a power plug hookup, like I did for the usb keyboard interface The DC voltages out are: Pin 1 = -5 volt Pin 2 = +12 volt Pin 3 = GND Pin 4 = +5 volt. 1 Quote Link to comment Share on other sites More sharing options...
Shift838 Posted August 27, 2016 Author Share Posted August 27, 2016 Thanks Greg! I may still be using the conversion drop from 12v to 5v since I am already powering the USB keyboard on the 5v. Quote Link to comment Share on other sites More sharing options...
Shift838 Posted September 1, 2016 Author Share Posted September 1, 2016 I got all my parts in for this mod. I just may be doing it this weekend. 1 Quote Link to comment Share on other sites More sharing options...
Omega-TI Posted September 1, 2016 Share Posted September 1, 2016 I got all my parts in for this mod. I just may be doing it this weekend. Would you please document each step with photos. This is probably something that others may want to duplicate in the future. THANKS. Quote Link to comment Share on other sites More sharing options...
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