Capacitor bulging and 30% drop in value.

[goraman]

I just had a NAD 3140 integrated amp compleatly rebuilt.
It had every Cap replaced with Elna Cerifine and Silnik.
It should be 40 watts RMS but after the rebuild 84 watts RMS before clipping.

After getting it back with a big bag of old parts I took one of the large power supply caps and carefully removed the inner core from the case.

The top of the cap had bulged and the value had diminished by over 30%
On removing the core it was still wet with oil (no dry spots) and no sign of burn marks.

should the case have been full with oil?
Some pictures of the inside of an electrolytic capacitor.

[Reid Malenfant]

It's not oil Jeff, it's electrolyte ;) Hense the capacitor type - electrolytic :)

Don't get that stuff on anything you value, it'll probably eat its way into just about anything.

The 30% drop in value may well be it's standard capacitance. Big electrolytics generally are rated +/- 50% ;)

[goraman]

It's not oil Jeff, it's electrolyte ;) Hense the capacitor type - electrolytic :)

Don't get that stuff on anything you value, it'll probably eat its way into just about anything.

The 30% drop in value may well be it's standard capacitance. Big electrolytics generally are rated +/- 50% ;)

WOW! 50%
The new power supply caps are Nichicon and the tech used alot higher value so it will take a long time for those to drop below spec.
This amp is being used to drive a pair of 92 db. Mission 762i's at very low level for back ground music but it is on 8 hours a day 7 days a week.
But output is just under or over a watt per side so it should go a long time.

Her store is the only one in town to use silver inter connects and Audison speaker cables from Italy or use a pair of Vintage British speakers for that matter.
To be honest it sounds glorious with the 45 hz.10db.+ switch made to equalize the roll off of a book shelf size monitor.

Customers have commented that the music sounds great,one lady made my wife turn it up.

[sq225917]

That electrolyte is strongly acidic, handle with care.

[Welder]

It’s a bit of a shocker isn’t it Jeff :stalks:
It’s not until you get the bloody things off the board and have a measure and look, you realise just how fecked they are.

Had this with my RC25 recently. The caps looked okay but on careful inspection off the board they were in a bit of a state.
I’m partially convinced that things like this go some way to explaining the "cor"and "wow" factor when a new amp is introduced into a system. Its not so much the new amp is intrinsically better; its more some components in the old one were knackered. :doh:

[goraman]

It’s a bit of a shocker isn’t it Jeff :stalks:
It’s not until you get the bloody things off the board and have a measure and look, you realise just how fecked they are.

Had this with my RC25 recently. The caps looked okay but on careful inspection off the board they were in a bit of a state.
I’m partially convinced that things like this go some way to explaining the "cor"and "wow" factor when a new amp is introduced into a system. Its not so much the new amp is intrinsically better; its more some components in the old one were knackered. :doh:

I think your right, I noticed you have a pair of Senn 595's in you gear.
If you ever get a deal on some 590's you may be surprised.