mimo Posted October 5, 2007 Share Posted October 5, 2007 both my 400s appear to be dead, I have tried 3 power supplies (all of which work on my 1200XL) and nothing! Is there any known weak point I can check? How do I go about checking the pcb? Please dont let them die! Quote Link to comment Share on other sites More sharing options...
LYNXGUY Posted October 5, 2007 Share Posted October 5, 2007 I am not sure if the 1200XL power supplies work with the 400's, might be different voltages and/or watts Quote Link to comment Share on other sites More sharing options...
Nukey Shay Posted October 5, 2007 Share Posted October 5, 2007 A 1200XL power supply is compatable with the older series. Quote Link to comment Share on other sites More sharing options...
LYNXGUY Posted October 6, 2007 Share Posted October 6, 2007 I am thinking that you might have a loose connection where the power supply goes into the computer, I have that same problem (loose connection) with my Indus Gt floppy drive but I have to tape the cord so that the floppy drive stays on, I will try to do something better when time allows. Quote Link to comment Share on other sites More sharing options...
deathtrappomegranate Posted October 6, 2007 Share Posted October 6, 2007 Do you have a multimeter? Quote Link to comment Share on other sites More sharing options...
mimo Posted October 6, 2007 Author Share Posted October 6, 2007 Do you have a multimeter? Yes, I have a multimeter,but I am no expert using it. I know that power is getting to the board, but not where it stops! I think it may be a problem with the voltage regulator, as I am only getting a reading on one of the legs, Quote Link to comment Share on other sites More sharing options...
+warerat Posted October 7, 2007 Share Posted October 7, 2007 Do you have a multimeter? Yes, I have a multimeter,but I am no expert using it. I know that power is getting to the board, but not where it stops! I think it may be a problem with the voltage regulator, as I am only getting a reading on one of the legs, Check for +5V. Find some 74LS family chips on the motherboard close to the cart slot. Place your multimeter negative on pin 7 on a 14-pin IC or pin 8 on a 16-pin IC. Place the positive on pin 14 on a 14-pin or pin 16 on a 16-pin. If your not seeing it check the input/output from the rectifier doides. If you don't see AC coming in, there is a problem with your power connector or interlock switch. Check the power regulators. Stick your multimeter ground on the middle leg of the 7805 or 7812. If you're facing them head on, pin 1 is on the left. Both pin 1's on the 7805 and 7812 should have a DC voltage >14V. Pin 3, leg on the right, should have the regulated voltage within 15%. Its not there, that one is dead. Quote Link to comment Share on other sites More sharing options...
tjlazer Posted October 8, 2007 Share Posted October 8, 2007 I have a 1200XL PS and it does NOT work on my Atari 800's. Just a FYI. I use a 1050 PS and it work fine on both the 800 an 1200XL! WTF Quote Link to comment Share on other sites More sharing options...
mimo Posted October 8, 2007 Author Share Posted October 8, 2007 I have a 1200XL PS and it does NOT work on my Atari 800's. Just a FYI. I use a 1050 PS and it work fine on both the 800 an 1200XL! WTF guess I had better find another PSU, it's worth a shot! Quote Link to comment Share on other sites More sharing options...
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