[Premium-Rx] Collins HF2050 problem

[R T]

A shorted cap would heat up fairly quickly. Go round the caps with a wet
finger after a short power-up. That might find the culprit.

Happy New Year 2016 to all....   Richard
On 29 Dec 2015 22:51, "Don Moman VE6JY" <ve6jy.1 at gmail.com> wrote:

> The +15v rail draws ~1.05 amps so presumably your substitute supply can
> supply in excess of that.
>
> In my experience in years past with the 2050's (30 something in quantity)
>  I don't ever recall the power supply being drawn down by a faulty upstream
> device, but rather it sometimes did a fine job of just failing on its own.
> I'm certainly not saying it can't, just no idea where to look.  As Peter
> suggested, uplugging the various boards would narrow it down a bit.  Maybe
> an IR thermometer or a finger might help locate a suspect too..
>
> Good luck, 73
> Don
> VE6JY
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> [image: Company Logo]
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> On Tue, Dec 29, 2015 at 8:28 PM, Richard Pederson <rpederson at eastlink.ca>
> wrote:
>
> > After finally getting some time off over the holidays I decided to listen
> > to my Collins HF2050. It has been sitting on a basement shelf for about 6
> > years, since I last used it and it was working great then.
> >
> > I turned it on and nothing. No screen, no lights, what a disappointment.
> I
> > checked out all the power supplies and the 15VDC supply nearest the
> > transformer fails under load (and the transformer buzzing increases too)
> .
> > This 15V supply outputs a nice 15.1VDC when the interface cable to the
> main
> > board is unattached, but is zero volts otherwise. The supply seems to be
> > fine, both the BD240 and 2N3055 test fine.
> >
> > I should also mention that I have checked out that 15VDC PS board (not
> the
> > tantalum caps) and replaced some of the other capacitors in particular
> the
> > disc capacitor on the (LM273) regulator IC, pin 13.
> >
> > As a quick test to check if the problem is within the PS itself or
> > upstream,  I substituted in my bench power supply to supply the 15VDC and
> > that too was drawn down in voltage. So all indications are that the issue
> > is not PS related but somewhere within the main system.
> >
> > But without a schematic or service manual to reference finding the issue
> > somewhere on one of the multitude of boards and display is almost
> > impossible.
> >
> > Any ideas or hints on where to look or test would be appreciated.
> >
> > Cheers,
> > Richard
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