[Boatanchors] Re: [Heathkit] Heathkit HP-23 bridge rectifier failure

[Peter Markavage]

Sounds like the breaker did its job. When diodes go, they go real fast
and probably faster than the timing associated with tripping a breaker.
Check the PIV on the current defective diodes, and when replacing, maybe
use some with a higher PIV if possible or use two in series for each leg.

Pete, wa2cwa

On Sat, 21 Jul 2007 15:41:20 -0400 "Dick KF4NS" <kf4nsradio at verizon.net>
writes:
> Just had a strange failure in my HP-23A (purchased from a friend last 
> 
> year for a spare) while using it with my Heathkit HW-100 on the 
> bench. 
> Had been running some tests and making some xmit adjustments and 
> quit 
> to go to lunch. Got back and the rig was off. Found the rig and 
> cable 
> ok so started checking the PS which would trip with each reset of 
> the 
> breaker in the HP-23. No mic was plugged in and vox was not on and 
> rig 
> was in recv mode.
> 
> Only took a short time to discover that the HV was shorted to 
> ground. 
> Suffered an avalanche through the four diodes in the bridge. All 
> looked fine, no burns or discoloration. They were all shorted.
> 
> This brings up a point. Is the breaker in there adequate? It appears 
> 
> not to me. I am so lucky that the xfmr was not destroyed. Has anyone 
> 
> replaced the breaker in there with a fuse or built a crowbar circuit 
> 
> to improve protection?
> 73, Dick KF4NS
> St Petersburg, FL 33714 USA
> Keep The Glow!