> -----Original Message----- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Seth > Morabito via cctalk > Sent: 01 October 2017 22:38 > To: cctalk@classiccmp.org > Subject: DECstation 5000/133 power supplies dead (H7826) > > All, > > I have two DECstation 5000/133s here with dead power supplies. I've done > some basic troubleshooting on both, and I've recapped the other, but they're > still dead dead dead. > > I don't see any obviously blown components, and the fuses are fine, but > several > of the caps I replaced WERE leaky. I inspected for bad traces but found none. > > So far it looks like the high voltage side is totally fine, but the low > voltage side is > completely dead. No activity. Switching transistors SEEM fine, but I haven't > pulled them to check them out of circuit. > > Is anyone intimately familiar with the H7826? Any obvious failure modes I > should check? >
The H7826 is the next one that I have to repair, mine is in a really bad way though, lots of leaks and corrosion, and I have not even started to look at it yet. If there is nothing happening on the secondary side then I would have expected the switching transistors to be the prime suspects, best remove them for testing as you suggest. Regards Rob
