airmailed Posted May 31, 2005 Report Share Posted May 31, 2005 hi there,i have a c64 psu and some others that i want to check with a multimeter (individual voltages coming from pins), i just wondered if i have to use the positive or negative probe of the meter or if it doesn't matter which probe i use to check the pins?all the bestadam Quote Link to comment Share on other sites More sharing options...
Screaming_Rabbit Posted May 31, 2005 Report Share Posted May 31, 2005 doesn't matter, it just shows you an other polarisation.Greets, Roger Quote Link to comment Share on other sites More sharing options...
airmailed Posted May 31, 2005 Author Report Share Posted May 31, 2005 thanks Roger,i need to find out which are positive and negative pins on one psu, will the meter show the opposite polarity if i use the wrong probe? (like will it always show positive if i use the red probe for instance?)all the bestadam Quote Link to comment Share on other sites More sharing options...
illogik Posted June 1, 2005 Report Share Posted June 1, 2005 hi adam,The C64 PSU has both AC(9V) and DC(5V) power. The AC doesn't have a positive/negative side, so it just measures 9V AC whenever you probe both pins. The DC has a + and - side ( "-" is ground here). The ground pin should be the pin in the middle of your plug. Put your black(-) probe there and with the other probe look for a pin where you get 5V. When you reverse the probes it will read -5V.So if you don't have any clue which pins are which, just look for two pins that measure 5V or -5V--> when it's 5V you got the red probe on the (most) positive pin when it's -5V you got the red probe on the (most) negative pin (ground). hope this helps, marcel Quote Link to comment Share on other sites More sharing options...
airmailed Posted June 1, 2005 Author Report Share Posted June 1, 2005 thanks marcel i'll try that out..the other psu is a +5 +12 -12 volts, using a 5 pin midi style connector, it sounds like your advice also applies well here, look for +5 and -5 then use the black probe on the (newly discovered) ground connector to find the +-12v pinsall the bestadam Quote Link to comment Share on other sites More sharing options...
illogik Posted June 2, 2005 Report Share Posted June 2, 2005 hi adam,yeahjust keep in mind that there is no -5V pin, you just read -5V when you put the red(+) probe on the ground pin (0V) and the black(-) probe on the +5V pin. cheers, marcel Quote Link to comment Share on other sites More sharing options...
kokoon Posted October 20, 2005 Report Share Posted October 20, 2005 excuse me but where did you get that combined PSU? that could be ideal for powering a MBFM? 5V DC and +12/-12 AC bipolar? Quote Link to comment Share on other sites More sharing options...
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