replacing +15v regulator on BA-11?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Mar 24 17:49:52 2004

>
>
> Anyone have experience with the +15v regulator buried deep inside the
> back of a BA11? (this an 11/34a actually)

Yes, I've totally stripped the PSU section of this box (I assume you mean
a BA11-K -- the 10.5" 11/34 cabinet).

>
> It appears one let go on me this morning. The symptom initial symptom
> was no +15/-15v, so I went to my garage and pulled the two supplies from
> a "spare" BA11. I replaced them and got the -5 and +20 back but no +15.

IIRC, the -15V regulator needs the +15V line to work. So when the latter
is down, the former doesn't work either.

>
> I should have known it would be the supply deepest inside the back of
> the thing, requiring I completely disconnect the back module. blah.

No it doesn't!. Remove the top and bottom covers from the 11/34, then
swing the box to the vertical position. Loosen the top screw each side,
remove the lower 2 screws each side and swing the PSU away (you've
already done this to remove the regulator bricks).

You'll see a unit under the trnasformer in the centre. There are some
little white plugs at the bottom -- unplug those (and the external ones
to the power controller if present). Unplug the white plastic edge
connector above them. Remove the screws on the bottom of the PSU (it's
either 3 or 4, I forget). The power control unit (relay box,
essentially) and the 15V regulator board now slip out of the back of the
PSU chassis. You cna now get to the +15V regulator to repair it.

The circuit is really simple, and repairing it shouldn't take that long!
I assume you have prints.

-tony
Received on Wed Mar 24 2004 - 17:49:52 GMT