Re: more on ACT CR230 repeater failure

["BruceR" <brNOSPAM@xxxxxxxxxx>]

In talking to Phil Kingery about this issue a couple of years ago, he
advised me to use high heat solder in doing repairs in this area, as the
heat will melt standard solder.  He also mentioned that the more signals
that pass through the unit, the lower the heat will be. Not sure I
understand why though.  The newer units (last couple of years or so)
have heat sinks added.

From:Dan Lanciani
ddl@danlan.*com

> In article <3l2mk1pu64s2dddm26l25ouq1daen08o4u@xxxxxxx>,
> MFHult@xxxxxxxxxxxxxxxxxxxxx (Marc F Hult) writes:
>> On 10 Oct 2005 22:56:52 GMT, ddl@danlan.*com (Dan Lanciani) wrote in
>> message <1331627@xxxxxxxxxxxxxxxxxxx>:
>>
>>> On closer examination it turns out that both pads of the zener had
>>> separated from the board (a good trick considering that one of them
>>> is part of a little ground plane).  The trace that supplies power
>>> to the drivers is routed through the zener's pad, so it's difficult
>>> to determine what happened.  Depending on the order of pad failure
>>> the drivers could have seen no voltage, high voltage, or anything
>>> in between.  There is a 50V electrolytic across the output which
>>> might break down and limit the voltage a bit.  Based on my initial
>>> measurements (but after I had probably disturbed the board) I'm
>>> leaning towards no voltage.
>>>
>>
>> Is this a 1 watt 1n47xx ?
>
> No, it's a 5W 1N5366.  I actually complained about the excessive heat
> about 5-6 years ago (the board was starting to discolor even then) but
> they said in effect that it was just a cosmetic issue since the zener
> was rated for enough power.  And I suspect the zener itself is fine,
> it's
> just the board that is destroyed...
>
>> I have an ACT CR225 also and considering
>> preemptively replacing with a higher wattage zener.
>
> Couldn't hurt.  If I decide to repair the repeater I'll probably
> mount a
> fresh zener away from the board, possibly with a heat sink.  The
> question
> of exactly how the failure was causing the effect it was causing
> remains.
>
> Dan Lanciani
> ddl@danlan.*com