full writeup here: http://www.glitchwrks.com/2019/06/05/pdp1110-psu-repair I finally fixed the power supply in my PDP-11/10S, it turned out to be a shorted bridge rectifier on the 5411086 board, which provides +15 VDC, LTC, and AC LO/DC LO. Unfortunately, when it failed, the rectifier burned up the edge connector traces for the AC input to the board. I ended up cutting the edge connector traces away (what was left) and soldering on a pigtail to connect to the Mate-n-Lok coming from the AC transformer. I added a 15A inline fuse, in the repair. For those who have original 5411086s that haven't failed yet, you might want to make up a little pigtail with an inline fuse holder. It'd be easy to make up such that it could plug into the existing harness without permanent modification, and it'll save your edge connector traces if the rectifier shorts. It can happen in the other regulator modules too, but they use a Mate-n-Lok instead of an edge connector, so any damage would be repairable. Anyway, the PDP-11/10S is back up and running! Thanks, Jonathan
On Wed, 5 Jun 2019, systems_glitch via vcf-midatlantic wrote:
full writeup here: http://www.glitchwrks.com/2019/06/05/pdp1110-psu-repair
(Go read this, it has photos.)
I finally fixed the power supply in my PDP-11/10S, it turned out to be a shorted bridge rectifier on the 5411086 board, which provides +15 VDC, LTC, and AC LO/DC LO. Unfortunately, when it failed, the rectifier burned up the
Very cool, and not the worst thing to repair. My 11/05 has been sitting around for years with some sort of power problem which I've been dreading, but this encourages me to work on it. I also appreciate the links to the archive.org scans of the manuals & prints. I have boxes full of physical copies and I'm reminded I should check before committing to scan any of them. -- Jameel Akari
Definitely have a go at it! Getting a 24 VAC transformer with sufficient current-supplying capacity for bench testing was really a huge step in the right direction for me. I've got the crimpers, pins, and shells for the various Mate-n-Lok connectors DEC used, so if you need a pigtail made up or something, let me know. I'll be building a permanent home for the 24 VAC transformer, with a current meter, so it's not just sitting on my desk with primary connections exposed and everything. Figure there's almost certainly more DEC power supply troubleshooting in my future :P Yeah, a lot of the stuff is already up, but do check that you don't have a more recent print, or one that includes a variant not currently shown! I personally prefer dead tree hardcopy to scrolling through schematics, so having a duplicate print set isn't the worst thing! Also, thanks for getting me the key to power this system on :) That's the copy you sent me, pictured in the writeup. Thanks, Jonathan On Thu, Jun 6, 2019 at 12:23 PM Jameel Akari via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
On Wed, 5 Jun 2019, systems_glitch via vcf-midatlantic wrote:
full writeup here: http://www.glitchwrks.com/2019/06/05/pdp1110-psu-repair
(Go read this, it has photos.)
I finally fixed the power supply in my PDP-11/10S, it turned out to be a shorted bridge rectifier on the 5411086 board, which provides +15 VDC, LTC, and AC LO/DC LO. Unfortunately, when it failed, the rectifier burned up the
Very cool, and not the worst thing to repair. My 11/05 has been sitting around for years with some sort of power problem which I've been dreading, but this encourages me to work on it.
I also appreciate the links to the archive.org scans of the manuals & prints. I have boxes full of physical copies and I'm reminded I should check before committing to scan any of them.
-- Jameel Akari
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systems_glitch