[Amps] Astron RS20A primary resistance

[Will Matney]

Gary,

1/2 voltage can be caused by a rectifier, main filter cap, or the voltage regulator. I'd check the voltage regulator first off to see if I had high enough DC voltage from the rectifiers going into the collectors of the pass transistors. If it's low there, it's in the transformer, rectifiers, or filter. A 20 amp supply generally is only 110 Vac. The biggest thing to fail on these is the regulator transistors because they handle all the power. Next would be a bad bridge rectifier. If it's not that, the regulator IC could be bad, the driver transistors, or the voltage divider resistor network used to set the output voltage. If you have the proper DC voltage going into the pass transistors, then it will be in the regulator circuit itself.

Best,

Will


*********** REPLY SEPARATOR  ***********

On 5/7/06 at 10:59 PM Gary Schafer wrote:

>I need to know what the primary resistance is of the Astron RS20A
>transformer. I would like to know the resistance of a 220 volt transformer
>and a 120 volt transformer.
>
>Maybe someone has a 220 volt RS20A that could measure the resistance across
>the power plug, that will do it.
>
> 
>
>I have a power supply here that is supposed to be a 120 volt unit but it
>looks like it has a 220 volt transformer as I only get around ½ the voltage
>out on 120. This transformer measures around 6 ohms primary resistance.
>
> 
>
>Thanks for any help.
>
> 
>
>73
>
>Gary  K4FMX
>
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