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Re: [Amps] Astron RS20A primary resistance

To: amps@contesting.com
Subject: Re: [Amps] Astron RS20A primary resistance
From: "Will Matney" <craxd1@verizon.net>
Reply-to: craxd1@verizon.net
Date: Mon, 08 May 2006 11:01:25 -0400
List-post: <mailto:amps@contesting.com>
Gary,

Ok, I thought it was one that was working at one time and had quit. It very 
well could be that Astron screwed up at the factory and used a 220 Vac 
transformer in place of one for 110 Vac. Or they could have been out of 
cabinets at the time that said 220 Vac and used a cabinet that read 110 Vac. 
It's untelling what could have happened. If it's never been used, I'd guess the 
regulators to be ok. If it is a 220 Vac transformer, most came wireadble for 
110 or 220 Vac in about everything. I wonder if those can be changed or did 
Astron use one that couldn't?

Best,

Will

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

On 5/8/06 at 10:23 AM Gary Schafer wrote:

>The low voltage is right out of the transformer secondary. It is about 1/2
>of what it should be.
>
>I used to be an astron distributor. I sold about a dozen of these supplies
>to a customer and he sent this one back saying it had low output. Never did
>get around to sending it back to the factory.
>
>They do supply these power supplies with 220 volt transformers on request.
>However this particular one was supposed to be 120 and it is marked as 120
>volts but all the symptoms of the voltages indicate that there is something
>other than a 120 volt transformer in it. 
>
>No markings on the transformer thus my request of what the primary
>resistance should be on a 120 volt and a 240 volt transformer.
>
>Just getting around to doing something with this thing after sitting around
>for several years.
>
>73
>Gary  K4FMX
>
>
>> -----Original Message-----
>> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
>> Behalf Of Will Matney
>> Sent: Monday, May 08, 2006 1:10 AM
>> To: amps@contesting.com
>> Subject: Re: [Amps] Astron RS20A primary resistance
>> 
>> 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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