Aleph3 recap

[Zen Mod]

just re-solder all these pads properly and do not worry

it was good for years , it will be good for few more

or - if that's too much of a burden for you , you can always send that bad amp to me , for proper disposal

[Dukja]

OK, I'll resolder it when the caps come in.

Bear with my ignorance, why is that pad so hot? I don't think the heat came from the NTC. It seems to be from the pad itself.

Oh, this is no burden to a senior research engineer at all. This is just a hobby. I only need to get my feet wet. I just plan to dig out my microelectronic textbook to have some fun. And you had enough fun already.

Thanks a lot for helping!

[Zen Mod]

hot pad - sort of chicken-egg dilemma

NTC is heating all the time that poor pad - solder is getting worse all the time , contact is getting worse all the time etc.

in fact - nothing to worry about , especially when you bring it back to proper state

[Dukja]

That make sense to me and was what I suspect. Maybe the pad can use some mini heatsink later.

And I do feel some 22mF cap a little budged at the top. Thanks a lot for all the help. This give me motivation and some expectation to restore this Aleph 3, if it already sound so good at current state.

You and others are great guys here and fun to talk to.

[ungie]

Given the internal heat generated in these amps, I would recommend that whatever power supply caps you choose should be rated 105degC NOT 85degC.

[Dukja]

Yea, I saw the cap temperature was pretty consistent around 105F after turning off for few minutes. So it may be a good idea for the longevity.

[KatieandDad]

Originally Posted by Dukja

Yea, I saw the cap temperature was pretty consistent around 105F after turning off for few minutes. So it may be a good idea for the longevity.

That's VERY WARM for electrolytic caps. They contain a jelly after all and the jelly will dry out if they get too warm.

I'm concerned that my F4 runs at just under 50 Degrees C.

[Dukja]

105 deg. F = 40 deg. C

I was messed up unit so actually 85C cap should be good enough.

Originally Posted by KatieandDad

That's VERY WARM for electrolytic caps. They contain a jelly after all and the jelly will dry out if they get too warm.

I'm concerned that my F4 runs at just under 50 Degrees C.

Are you also confused by C & F?

[grimberg]

When replacing the caps, look for 105°C. Something like this one, if it fits in the same physical space:

Digi-Key - P10635-ND (Manufacturer - ECE-T1HA393FA)


Don't feel bad about getting confused by different systems, even rocket scientists do it some times.

NASAs metric confusion caused Mars orbiter loss - CNN

[JoelS]

not that there's anything wrong with replacing all the caps in your amp, but if you want to save a few bucks you might try replacing the small caps first and see if that solves your problem. the smaller DC blocking caps in the signal path will cause a loss of low end when they start going bad, which sounds like the problem you started describing. when the big filter caps in the power supply go bad it will cause hum and buzz problems in your audio due to ripple appearing on the power supply rails.

-Joel