Hi,
I have used this unit for severals years, this is the older unit with external PSU.
Of time to time the +16 Volts was presenting an erratic behavior from +16Volts to 0Volts and I changed the LM317 voltage regulator and the PSU was working well for few seconds and again show the same behavior to 0volts in the +16volts.
I analyzed the schematic (btw: that is very simple network at all!) and before I figure nothing rare in others components inside of this simple PSU, I checked the input voltage and found -50Volts and +50Volts in both LM IC 317, 337 respectively....This look like very high voltage to me because the data sheet say "Input−Output Voltage Differential" Max 40Volts.......and 50Volts minus 16 Volts (50 - 16 = 34) are 34Volts that is to near to the limit! this can be causing my -16Volts LM317 regulator go bad every time I change it?...
I want to be noted the very high temperature of this units is common in this PSU from I purchased and this the same in anothers units of the same model with external PSU; look like this PSU is in the limit, not for the unit itself but the LM IC voltage regulators are in the power and input voltage limit!! .
I am thinking to interchange the LM317 and LM337 pair for another IC regulators with more power management like the LT1085 and LT1033 in place for the +/-16Volts.
My question is: Someone have had this same problems before with this IC LM317??......Is my situation a typical behavior of this "near limit situation" for the LM IC voltage regulators?
Thanks
Opacheco
I have used this unit for severals years, this is the older unit with external PSU.
Of time to time the +16 Volts was presenting an erratic behavior from +16Volts to 0Volts and I changed the LM317 voltage regulator and the PSU was working well for few seconds and again show the same behavior to 0volts in the +16volts.
I analyzed the schematic (btw: that is very simple network at all!) and before I figure nothing rare in others components inside of this simple PSU, I checked the input voltage and found -50Volts and +50Volts in both LM IC 317, 337 respectively....This look like very high voltage to me because the data sheet say "Input−Output Voltage Differential" Max 40Volts.......and 50Volts minus 16 Volts (50 - 16 = 34) are 34Volts that is to near to the limit! this can be causing my -16Volts LM317 regulator go bad every time I change it?...
I want to be noted the very high temperature of this units is common in this PSU from I purchased and this the same in anothers units of the same model with external PSU; look like this PSU is in the limit, not for the unit itself but the LM IC voltage regulators are in the power and input voltage limit!! .
I am thinking to interchange the LM317 and LM337 pair for another IC regulators with more power management like the LT1085 and LT1033 in place for the +/-16Volts.
My question is: Someone have had this same problems before with this IC LM317??......Is my situation a typical behavior of this "near limit situation" for the LM IC voltage regulators?
Thanks
Opacheco