DEC H7260 PSU fault

Adrian Graham binarydinosaurs at
Sat Jan 27 12:51:43 CST 2018

> On 27 Jan 2018, at 17:04, Jules Richardson via cctalk <cctalk at> wrote:
> On 01/26/2018 07:15 PM, Jules Richardson via cctalk wrote:
>> After that... well, I need to work out how to get the entire supply
>> assembly to start up while it's open, so that I can work on it outside the
>> machine - then I can at least start looking for differences between the two
>> supplies (boy, are those things complex, but maybe I'll get lucky and it's
>> a bad solder joint or cap somewhere)
> OK, now I feel like an idiot :-)

We’ve all been there including me earlier! When you have two PSUs in a machine but only one is connected to the mains make sure you don’t connect a flying lead from the OTHER one and spend 2 hours wondering why the bloody thing doesn’t work.

> Anyway, I tweaked my loads to draw a little more current - and bingo! I'm now getting stable +5V and +12V outputs on both PSUs, a working card cage fan, and the DC OK light comes on.

This is good, particularly since my own BA123 has been sat in 3 garages then a utility room since 1998, you’re making me think it MIGHT just power up without any issues. 

And THEN I can tackle the RL02 that’s sat on top of it… being able to read my own source code from the 80s would be a special thing indeed.

Binary Dinosaurs - Celebrating Computing History from 1972 onwards
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