Willsy Posted February 28, 2013 Share Posted February 28, 2013 Does anyone know what the maximum current we can draw from the TI cartridge port is? Marc? Matthew? Stuart? Quote Link to comment Share on other sites More sharing options...
Stuart Posted February 28, 2013 Share Posted February 28, 2013 If the tracks on the PCB start to glow, then you need to back it off a bit. No idea of a value as such, but consider that you can plug in a Gramkracker plus a cartridge, and a Gramkracker is pretty much stuffed full of chips (many of them are low power RAMs though?). 1 Quote Link to comment Share on other sites More sharing options...
matthew180 Posted February 28, 2013 Share Posted February 28, 2013 I'm not sure, I never looked into it. I have TI's internal 99/4A service manual (you can get them on ebay), so when I get a chance I will see if it indicates any sort of power specs for the cartridge port. The power supply is small though, I think about 2A on the 5V line I think, and it already runs very hot. I would say 250ma to 300ma would be pushing it. 500ma does not sound like a lot until you say "half an amp"! Quote Link to comment Share on other sites More sharing options...
+Vorticon Posted February 28, 2013 Share Posted February 28, 2013 Does anyone know what the maximum current we can draw from the TI cartridge port is? Marc? Matthew? Stuart? What exactly are you trying to do? Maybe a robotics project for this year's Faire? Quote Link to comment Share on other sites More sharing options...
marc.hull Posted February 28, 2013 Share Posted February 28, 2013 Does anyone know what the maximum current we can draw from the TI cartridge port is? Marc? Matthew? Stuart? Available current = total PS output current - what is being used in the console... .... Seriously. The 5V rails are all interconnected in the console so.. You could always measure the current at the PS connector on the mother board to see what is being drawn. Plugging a cart in and having the speech synth plugged in as well would give you a worst case (assuming you don't have 32K or other goodies inside the machine as well.) Quote Link to comment Share on other sites More sharing options...
Stuart Posted February 28, 2013 Share Posted February 28, 2013 A few figures ... The console with the XB cartridge fitted draws around 950mA on the +5V line. The console draws around 330mA on the +12V line. The main output transistor on the power supply 5V circuit is rated at 3A. The 12V regulator is rated at 1.5A. The diodes in the bridge rectifier supplying the 5V and 12V circuits are rated at 1A each (so if two are in use at any time, that's a rating of 2A?) The transformer is rated at 1.6A, shared between the 5V and 12V supplies. I would think that anything 'digital' (within reason) you want to hang off the port is likely to be OK, but motors, relays and so on are not. You could of course do away with the transformer and power supply and run the console off an ATX supply, which would give all the power you're likely to need ... Quote Link to comment Share on other sites More sharing options...
Willsy Posted March 1, 2013 Author Share Posted March 1, 2013 What exactly are you trying to do? Maybe a robotics project for this year's Faire? I could tell you, but I'd have to kill you! Quote Link to comment Share on other sites More sharing options...
Willsy Posted March 1, 2013 Author Share Posted March 1, 2013 A few figures ... The console with the XB cartridge fitted draws around 950mA on the +5V line. The console draws around 330mA on the +12V line. The main output transistor on the power supply 5V circuit is rated at 3A. The 12V regulator is rated at 1.5A. The diodes in the bridge rectifier supplying the 5V and 12V circuits are rated at 1A each (so if two are in use at any time, that's a rating of 2A?) The transformer is rated at 1.6A, shared between the 5V and 12V supplies. I would think that anything 'digital' (within reason) you want to hang off the port is likely to be OK, but motors, relays and so on are not. You could of course do away with the transformer and power supply and run the console off an ATX supply, which would give all the power you're likely to need ... Thanks Stuart! Quote Link to comment Share on other sites More sharing options...
matthew180 Posted March 1, 2013 Share Posted March 1, 2013 Nice analysis Stuart! I thought the later PS was a switcher? If so, I would expect the voltage/current in the input stage to be lower, thus the reason the transformer is only rated for 1.5A, but probably much higher voltage. The output regs are usually a good indicator of the supply's capability. Did you measure the console current without the XB cart? It might be nice to see the difference. Quote Link to comment Share on other sites More sharing options...
Stuart Posted March 1, 2013 Share Posted March 1, 2013 Nice analysis Stuart! I thought the later PS was a switcher? If so, I would expect the voltage/current in the input stage to be lower, thus the reason the transformer is only rated for 1.5A, but probably much higher voltage. The output regs are usually a good indicator of the supply's capability. Did you measure the console current without the XB cart? It might be nice to see the difference. I done the current measurements quite a while ago (and noted them). I didn't note the current without the XB cartridge, but from memory the difference was only around 50mA or so. The +5V circuit in the 'normal' power supply already is a switching supply, but the +12V (and -5V) supplies are plain regulators. Most of the heat I think comes from the +12V regulator which is mounted on that heatsink strip. Quote Link to comment Share on other sites More sharing options...
apersson850 Posted March 2, 2013 Share Posted March 2, 2013 The diodes in the bridge rectifier supplying the 5V and 12V circuits are rated at 1A each (so if two are in use at any time, that's a rating of 2A?) No. There are four diodes in a bridge, and two at a time are in use, but the two in use each carry the full load, since they are effectively connected in series. Quote Link to comment Share on other sites More sharing options...
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