Hi.

Can you post pictures of the inside psu, ideally you want 13.8V for a Ham psu so a Lm7812 would do with a pass transistor..

The 15VDC supply unit is underused in its capability. Both transformers secondaries have 16 - 11 - 0 - 11 - 16 VAC winding terminals. Only a 0 - 11 tap section is in use at each transformer, producing 15VDC unregulated after plain 30A full wave rectifiers and filtering.
Both equal supply output terminals are paralleled at the front panel.
Adding 5 V to the AC secondary using the 16VAC tap instead of the 11VAC tap can bring the useable voltage to about 20VDC, enough overhead to insert pass transistors regulation to achieve 13.8 - 14 VDC
Transformer cores are 5 inch x 5 inch x 2 inch (1" x 6" ruler placed on top), have no access to center tap to separate windings and parallel them to double current capability unless damaging the wrapping. Filtering capacitors are 61000μF/50V. The relay at center delays a few seconds the inrush as 'soft start' when turning on.

 

Hi.


The 15VDC supply unit is underused in its capability. Both transformers secondaries have 16 - 11 - 0 - 11 - 16 VAC winding terminals. Only a 0 - 11 tap section is in use at each transformer, producing 15VDC unregulated after plain 30A full wave rectifiers and filtering.
Both equal supply output terminals are paralleled at the front panel.
Adding 5 V to the AC secondary using the 16VAC tap instead of the 11VAC tap can bring the useable voltage to about 20VDC, enough overhead to insert pass transistors regulation to achieve 13.8 - 14 VDC
Transformer cores are 5 inch x 5 inch x 2 inch (1" x 6" ruler placed on top), have no access to center tap to separate windings and parallel them to double current capability unless damaging the wrapping. Filtering capacitors are 61000μF/50V. The relay at center delays a few seconds the inrush as 'soft start' when turning on.

View attachment 269918View attachment 269919

Nice boat-anchor.

 

Keep the Transformers and fix them up as best You can,
throw away the rest and start over.
.
.
.

 

Hi.


The 15VDC supply unit is underused in its capability. Both transformers secondaries have 16 - 11 - 0 - 11 - 16 VAC winding terminals. Only a 0 - 11 tap section is in use at each transformer, producing 15VDC unregulated after plain 30A full wave rectifiers and filtering.
Both equal supply output terminals are paralleled at the front panel.
Adding 5 V to the AC secondary using the 16VAC tap instead of the 11VAC tap can bring the useable voltage to about 20VDC, enough overhead to insert pass transistors regulation to achieve 13.8 - 14 VDC
Transformer cores are 5 inch x 5 inch x 2 inch (1" x 6" ruler placed on top), have no access to center tap to separate windings and parallel them to double current capability unless damaging the wrapping. Filtering capacitors are 61000μF/50V. The relay at center delays a few seconds the inrush as 'soft start' when turning on.

View attachment 269918View attachment 269919

Looks like a relay to switch the output on, i would rebuild it using the 16V tap and a LM317 and Pnp pass transistor, and set it for 13.8V..

 

We still don't know that this is the source of the "Hum".

But, if You insist ..........
For a Regulator that will eliminate the Fuses, and provide an extremely quiet Output,
use a MIC-5158 Chip,
which will drive any huge N-Channel-FET, ( on a very large Heat-Sink ),
and provides built-in Current-Limiting.

Suggested FET ........ IXFH140N10P-ND, ~$10.oo each
Replace the Bulk Storage Capacitors and throw-out the old ones.
.
.
.

 

Thanks.

Looks like a relay to switch the output on, i would rebuild it using the 16V tap and a LM317 and Pnp pass transistor, and set it for 13.8V...

Have a couple of new Motorola 2N5685 transistors in my bins, are NPN, will see if can be used for pass transistors after rising the voltage near 20VDC...
The relay short circuits a resistor that charges the capacitors slowly at turn-on, after the capacitor voltage has risen enough that clicks the relay coil on.

Rectifier out + -------------------------------A--------/ ----------B------------------capacitor +----------||----------ground.
A and B are the N.O. relay contacts that have resistors as path between them. Its coil is fed by capacitor+ and clicks after a few seconds.

Weighed the animal just to confirm, 43.6 pounds ( And that is with the capacitors discharged ! ) But have no boat.

 

The beauty of a Pnp is that it takes all the heavy current and doesn't drop any voltage , BD250C is a good transistor. Like this..

 

Okay, so with the 16V taps you'll get plenty of headroom for regulation. Astron's power supplies are well-documented, so borrowing their regulator design is an option.
http://www.repeater-builder.com/astron/astron-index.html