[Amps] AL80A

[R at contesting.com]

On Mar 30, 2006, at 7:15 AM, Georgens, Tom wrote:

> Hello -
>
> My AL80A in Barbados failed after years of reliable service.
>
> It looks like all of the diodes on the rectifier board are shorted.  I
> also noticed that one of the diodes had a chunk blown out of it.  I can
> obviously replace the diodes but I would like to know why they all
> failed.  Is it possible that if one diode fails, they all fail?

Yes, which is the usual case because series rectifiers are like 
dominoes.

> Or, should I be concerned about a problem further down stream.

This is a possibility -- especially with an AL-80 because it uses no 
glitch R in the +HV to limit fault-I during an anomaly -- such as an 
intermittent  +HV arc to ground.

> Rudimentary ohmmeter checks of the capacitor bank/load looked normal

A white deposit near the pressure vent indicates a kaput electrolytic.  
When one or more electrolytics in a string goes bad, it's best to 
change out all of 'em.
>
> Thanks for your help.
>
> Tom W2SC 8P5A
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Rich Measures, 805.386.3734, AG6K, www.somis.org