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Old 9th Apr 2021, 3:53 pm   #17
TonyDuell
Dekatron
 
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
Default Re: Weir HSS100/4 PSU blowup

ARGH!

I got the BZW06-13 and BUW12A from Farnell and fitted them. Also replaced all the electrolytic capacitors in the PSU with new ones from Farnell.

Powered up with a lamp limiter initially, then shorted out the series bulb. The outputs came up, but the thing was still oscillating at an audible frequnency. Then (lamp limiter not in circuit) I tried a very moderate load on the 5V rail, about 1A. The result was the new transistor and zener are shorted, the expensive fuse on the PSU board has blown.

I am at a loss as to what to try next. I will 'ring' the transformer in case it's shorted turns but the fact that it works at all suggests that's not the problem. Everything else I've checked seems fine.
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