[OT] Astron Power Supply Current Meter

[Phil Hystad-3]

Off topic but I hope there are a few Astron power supply experts out there in the Elecraft community.

I have two Astron RS-35M power supplies.  I use them both.  One powers my K3 and the other powers a lot of little things on the bench plus my back up rig, an Icom 756 Pro III.  So, both are usually on most of the time.

Last night I noticed that neither was reading any current when they both should have been reading current.  The voltmeters seem to be reading the right voltage but no current readings.  I did some tests such as key down at 100 watts on the K3 for one power supply and then the Pro III for the other power supply.  Yes, transmitting just fine but no current reading.  Meter needle doesn't move.

I am not sure when this happened but I am surprised that both power supply current meters busted.  The power supplies are not located in a location where I look at them all the time so I have no idea how long this has been like this.  I know they used to work.

So, has anyone heard of Astron power supply current meters going defunct?  Is this a common problem.  It is sure common around my shack.

Thanks for any help.

73, phil, K7PEH

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[Barry]

I have a 20 year old RS75M and no problem with the meters.  have you tried tapping them while drawing some current?
Barry W2UP

[KC7HP]

I just bought a used RM-50M and found this thread looking up meter troubleshooting.  On mine, the voltmeter reads really low even though I have 13.8V at output terminals.  Please consider the following:

Introductory Information on Astron™ power supplies

and, specific to meters:

Astron Power Supply Meter Modification

[KC7HP]

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[nm4v]

Someone may have suggested this but here goes. Astron uses an odd way of reading the amperage on their units. Instead of reading the current through all the transistors they read the current across only one of them. Look for the meter leads where they attach across the large resistor near one of the 2N3771 transistors. If the transistor or resistor goes out the supply will still produce correct voltage and enough current to run a 100 watt rig but will not display the current.

Charles, NM4V