[Milsurplus] I came upon a R390A/URR EAC

[marsan .]

Hello Michael,


What would you expect ? A burning smell is always a bad sign.  Hissing/Boiling sound also.  One tip I can give you or everyone just in common. This is what I would recommend.


Using a variac is ok.


First: The better way is to put the receiver away for a few days . Just to let it "dry" in case  it was stored in a moisture shed shack or whatever.


Second: open up the cabinet and go through a visual inspection.


Third: connect the receiver to a glowing bulb (in the live wire/phase) of same watts  as the receiver should take.   Then connect the variac to the other side of the glowing bulb. So the bulb is put between the variac and receiver (in the live wire). Stay with the proces of starting up. Don't be hasty. Smoothing capacitors should taken a lot of time to reform.



If the receiver is short circuit than the shortcircuit current will be taken over by the bulb which will "burn".  The way  the burn glows shows if a receiver is short circuited or not.

Reckon that if a glowing bulb is connected  the receiver will be fed with a lower power supply (voltage drop  by glowing/burning) glowing bulb) so oscillators cannot start up properly.

This way you will protect at least the electrolytics in the powersupply, the smoothing coil  and the coupling capacitors in the LF audio stage and the primairy side of the audio transformer.

In case a noise filter is installed in the powersupply check the X- Y- Z   capacitors between the live, neutral , ground/chassis/massa.

Monitor the smoothing capacitors temperature. Running warm or hot or staying the same.

Or just by measuring  the current drawn from the wall socket. Or secundairy  from the powersupply transformer.

Succes
Maswisale




: Milsurplus <milsurplus-bounces at mailman.qth.net> namens Michael Holdren <mhdesign at gmail.com>
Verzonden: donderdag 4 februari 2016 08:04
Aan: milsurplus at mailman.qth.net
Onderwerp: Re: [Milsurplus] I came upon a R390A/URR EAC

Hi everyone, I'm new to this list. I purchased the other Collins R-390A that Hutch is talking about.

I have a quick question: should there be a burning smell when I power it on?

After inspecting the unit (looking around the insides without removing anything), I realized the radio is actually pretty clean even though it doesn't really look like it on the top, the bottom is nearly immaculate. So I decided to try using a variac to slowly power up the radio. I went up to about 10v and after only about 5 minutes, I noticed an electronic burning smell. Could this be the reforming of the capacitors, or is it something else/bad?

Thanks,

Michael



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