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S5000: Overheating Power Transformer?

Posted: Fri Mar 21, 2014 6:20 am
by ninja6485
So I noticed a burning smell and a little bit of smoke coming from my s5000 near the power supply. Everything was on and working fine, so I turned it off and unplugged it. I set it aside a while, and tonight I opened it up: still turns on fine, loads up fine etc, BUT after a few moments something near the power supply starts to smell. There is a reddish brown goo all over many components inside, which looks like some sort of glue(glyptal?). This glue has clearly burned away between the transformer and some big metal thing, and there appears to be very (very)slight traces of a more liquidy amber colored stuff which may or may not be melted glue on the transformer. The board its on looks very clean, the caps are not domed nor are they leaking. I turned it on again one last time to watch the transformer, and it looks like there is a slight glowing at the very bottom - almost under it - where it connects to the board. perhaps a connection is getting red hot (bright orange actually)? This accompanies the smell, and goes away immediately when I turn it off. What lead me to suspect the transformer in the first place was that it looked a bit dodgy when I was inspecting the board, and it seemed to be where the smoke and smell were coming from. It's a Dash 2 b-5. Leaving the s5000 off for now, since I don't want to damage anything. Can post pics as well! Any help with this situation is greatly appreciated!

A final thought: could the hard drive mounted in it be overtaxing the power supply? may try unplugging it and turning it on again to see if it does it, but it feel like every time I hit the switch I'm rolling the dice. My biggest fear is a fire that would damage more of the circuit board.

Re: S5000: Overheating Power Transformer?

Posted: Mon Jan 26, 2015 1:24 pm
by madtheory
Too risky to diagnose over the web. Take it to a tech.

Re: S5000: Overheating Power Transformer?

Posted: Mon Jan 26, 2015 7:40 pm
by db0451
Yeah, don’t skimp on safety where AC is involved.

This comes after I got a nice sizeable jolt from a PSU board I had tested as faulty and then unplugged earlier today. In retrospect, it was moronic to handle it without looking at what I was touching. But these things are easy to forget if vigilance and caution are not engrained into your methods. At least it was clearly less than 240 V that reached me… makes me wonder why I was reading 0 V on all the actual outputs to the main board. :?

Re: S5000: Overheating Power Transformer?

Posted: Mon Jan 26, 2015 7:53 pm
by ninja6485
Ok, good to know!Thanks guys. I'm definitely not touching it then. It power's on, and works perfectly otherwise, but I'm keeping it off and unplugged in the meantime.

Re: S5000: Overheating Power Transformer?

Posted: Mon Feb 02, 2015 3:00 am
by rschnier
Some thoughts:

The glowing red/orange under the transformer is of great concern, obviously...high current flowing through a small connection or wires. Question is what's causing the high current. I'd suspect that the windings of the transformer have partially shorted -- transformers are wound with varnish-coated wire and this insulating varnish sometimes degrades with time, heat, etc. As a tech, the first thing I would do is disconnect the transformer secondary from the rest of the power supply (or remove it from the unit entirely, which would also perhaps reveal physical damage that would be another clue) and power it up by itself. If the transformer itself proves to be OK, then I'd go hunting for things downstream in the power supply that would cause high current draw -- shorted bridge rectifier or diodes, shorted filtering or decoupling capacitors, and so forth.

In general, the way these things are diagnosed is to disconnect the stages from each other, examine each stage, and go through a process of downstream elimination until the cause(s) are found. Once the cause is found, the fix is often fairly anti-climactic (assuming that proper replacement parts are available). :)

Assuming you were to take it to a tech, this is what they would most likely do.