We were troubleshooting a power supply today and the faulty component turned out to be a 0.1 ohm resistor (rated @ 20 watts).
This resistor was the only thing between chassis ground and the negative dc side of the bridge...
This is a standard full wave bridge rectifier connected by two wires to a xformer on the ac side and a positive and negative terminal on the dc side. It's a 28VDC power supply 120VAC input.
any ideas on what the purpose of this 0.1 ohm resistor is?
One guy said it was part of the filter but there were smoothing caps on the other (positive terminal) side that serve that purpose (along with the bleeder resistor), so I'm not buying it... Another guy said something about eliminating noise from high frequencies, but I'm not sure about that either... although the application does happen to be an RF transmitter operating in the 100-ish megahertz range.
This resistor was the only thing between chassis ground and the negative dc side of the bridge...
This is a standard full wave bridge rectifier connected by two wires to a xformer on the ac side and a positive and negative terminal on the dc side. It's a 28VDC power supply 120VAC input.
any ideas on what the purpose of this 0.1 ohm resistor is?
One guy said it was part of the filter but there were smoothing caps on the other (positive terminal) side that serve that purpose (along with the bleeder resistor), so I'm not buying it... Another guy said something about eliminating noise from high frequencies, but I'm not sure about that either... although the application does happen to be an RF transmitter operating in the 100-ish megahertz range.