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XsamuraiX 17th April 2019 07:39 PM

Mf rating ok?
 
Just tested 2 large 22000uf caps from my amp and one is coming back as 19000 and the other at 20000. Some lil swelling on top too.

Are they still ok? Or time to change them?

nigelwright7557 17th April 2019 07:56 PM

Electrolytics tend to come with up to +/- 20% tolerance value so they are well within spec.
Unless they are really old I would leave them.

DF96 18th April 2019 10:21 AM

The swelling may indicate a problem. The capacitance value is well within tolerance so is no problem.

Mooly 18th April 2019 10:29 AM

If the swelling is occuring in the actual aluminium can then its probably an indicator that all is not well. If its a plastic cap secured by the shrink wrap outer that is distorted then its probably normal.

XsamuraiX 18th April 2019 10:41 AM

It's the plastic with the metal top.

Just eliminating parts as my Pioneer AV amp powers up but rarely the speakers work.

Onto the FETs and transistors then...

1 quick question, the FETs/transistors that have 4 pins, what are those? Regulators?

Mooly 18th April 2019 03:50 PM

Maybe, maybe not... post a picture of that part of the circuit and we'll identify them for you :)

Random speaker operation could be something as simple as a dry joint somewhere, perhaps causing a missing rail or causing a DC offset that prevents the relay closing.

XsamuraiX 19th April 2019 11:12 PM

Ok, here are the pictures.


I have had a look at the solder joints, a few do look cracked (got that circle crack inside the solder joint) and some look a much deeper shade of gret to the rest.


The pics are the mosfets along with the things next to the, and the other side, both taken from the amps amp output stage?



The other pics are what I do not know what they are, both seem to have a lil burnt section to the underside.


Imgur: The magic of the Internet


Imgur: The magic of the Internet


Imgur: The magic of the Internet


Imgur: The magic of the Internet


Imgur: The magic of the Internet

Mooly 20th April 2019 06:45 AM

I think I can make out IRF9340 on the board which means they are FET's. The four connections are external to the device and so you would have to look at the circuit diagram to see how they are configured. I would doubt they are the problem in any case.

All suspect joints need resoldering, taking care not to cause any accidental shorts anywhere.

XsamuraiX 20th April 2019 03:35 PM

Ok Mooly. The 2 pin are rectifiers or something?

Mooly 20th April 2019 05:29 PM

Well the IRF FET's have 3 pins (G,D and S) and so I'm assuming they are using the tab of the device to access the 'drain' connection as the tab is electrically connected to that middle pin.


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