Re: more on ACT CR230 repeater failure

[ddl@danlan.*com (Dan Lanciani)]

In article <BmK2f.49$Hs.18@xxxxxxxxxxxxxxxxxxxx>, brNOSPAM@xxxxxxxxxx (BruceR) writes:

| In talking to Phil Kingery about this issue a couple of years ago,

Interesting.  He wouldn't admit to me that there _was_ an issue. :(

| he
| advised me to use high heat solder in doing repairs in this area, as the
| heat will melt standard solder.

Yikes.  It's a pretty bad design that requires hard solder for temperature
reasons, and they stuck an 85C capacitor right next to the zener.  In any
case, it wasn't the solder but the board material that failed.

| 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 zener is being used more-or-less as a shunt regulator.  The more power
used by the output drivers the less the zener has to dissipate as waste heat,
at least to a first approximation.  However, I assume the zener is also
conducting in the forward direction to charge the dropping capacitor on the
positive half of the cycle and it may end up passing more current then when
the load is higher.  Regardless, one would hope that they designed the device
to run for long periods with no signals...

| The newer units (last couple of years or so)
| have heat sinks added.

Yet still no UL sticker. :(

				Dan Lanciani
				ddl@danlan.*com