Power Supply Problem

[John Q. Doe]

Were does someone find a Variac?

I've experienced the same problem described, HW101/HP23B.
Temporary solution was to swap power supplies, however, as my
collection grows so does the need for fixing the wayward HP23B.
Also, when powering up a purchase that may not have had power
applied for a length of time, I know it is wise to use a Variac
to allow electrolytics to reform. I've just never run accross a
Variac at swap meets, etc., or didn't recognize what it was.
Could some knowledgable soul educate me?

                                    Mike (KE4HBA)




______________________________ Reply Separator _________________________________
Subject: Re: Power Supply Problem
Author:  cfandt at SERVTECH.COM at ORL-SMTP-G
Date:    10/7/97 2:27 PM


At 16:46 06-10-97 -0700, you wrote:
>I've got a problem with the HP-23B power supply I use with my HW-101.
  -- snip --
>What are the suspect components?  Are items such as the transformer and the
>filter caps still available?

Have no -23B manual or unit on hand but feeling here is one or more of the
filter caps have gotten quite leaky or nearly shorted. This would draw more
current -yet not enough to immediately pop a breaker or smoke a fuse but
just enough until they've gotten too annoyed by the extra current thru them.

Quick test is to hunt up a cap with similar value and an equal or higher
voltage in your parts box (or from a fellow ham) and swap out the suspected
cap. Make sure the test cap is relatively fresh or recently formed.
Otherwise, use a Variac to slowly run up the line voltage to form the cap.
Don't just bridge the suspected cap, though. 'Scope also should show some
degree of ripple higher than a volt or two if a cap is failing -depending
upon what the original cap value had been.

Anybody have a ripple level notation in their -23B schematic for this gentleman?


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