Monthly Archives: March 2020

H7874 Power Supply

Posted on March 29, 2020 by rjarratt

The H7874 is the power supply  used in the BA4xx and R400x enclosures, such as several machines in the VAX 4000 series. I have a VAX 4000-500 in a BA440. I had some problems with this power supply that seemed … Continue reading →

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Further Analysis of the VAXmate H7270 PSU Failure

Posted on March 28, 2020 by rjarratt

I have been doing further analysis of the failure of my VAXmate’s H7270 PSU. To start with the schematics are now greatly improved. I am still not sure how correct they are, but here are the latest and greatest: I … Continue reading →

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