Hello all,
I am ordering caps to recap a 5800 and figure I might as well “upgrade” them a bit in the process since it doesn’t cost much as long as one isn’t trying to go boutique.
Is there a minimum ripple current rating I should be looking for with the four 4700uf caps?
There is plenty of chatter on the web that the Nichicon KG gold tune caps are good for power supply use, but their rc is rated at 1.7a on the 25v versions. Is this enough? I ask because I can find caps with nearly twice that.
Thanks
I am ordering caps to recap a 5800 and figure I might as well “upgrade” them a bit in the process since it doesn’t cost much as long as one isn’t trying to go boutique.
Is there a minimum ripple current rating I should be looking for with the four 4700uf caps?
There is plenty of chatter on the web that the Nichicon KG gold tune caps are good for power supply use, but their rc is rated at 1.7a on the 25v versions. Is this enough? I ask because I can find caps with nearly twice that.
Thanks
More is usually better. More ripple current, more DC voltage, more uF, more temperature.
But less ESR.
But less ESR.
Thanks I appreciate that, seems to be the best way to go. Curious why the KG get such a following with mediocre specs (not that 1.7a is on the lower end of rc, but they are also only an 85 deg cap too. I’d expect something “so good” to be over 2a and 105 deg just looking at other choices..
I'll disagree with Ray on this slightly. It's best not to increase capacitance, a little is okay. You are further ahead with slightly higher voltage and that makes the case large enough to fit.
Select on general quality and physical size first. Maximum ripple ratings are useful. Whether it is 125° or 85° doesn't matter. Your amplifier doesn't get that hot.
However, look at the ripple waveform. If your filter capacitors are good, I wouldn't touch them. You will not hear a difference (despite claims to the contrary). Local bypass caps make more of a difference, and those were probably installed at the factory.
Select on general quality and physical size first. Maximum ripple ratings are useful. Whether it is 125° or 85° doesn't matter. Your amplifier doesn't get that hot.
However, look at the ripple waveform. If your filter capacitors are good, I wouldn't touch them. You will not hear a difference (despite claims to the contrary). Local bypass caps make more of a difference, and those were probably installed at the factory.
Turns out those four 4700uF capacitors are only for the input/driver stages, and not for the output stages,
which have four 24,000uF, one per polarity per channel. That's more like it.
which have four 24,000uF, one per polarity per channel. That's more like it.
Thanks anatech. I am having it pulled apart to change the power switch, and having the tech change the caps on the amp boards since he is in there and it is easy.
He is going to test the four big caps, which I hope/think should be fine. I figured it is easy and cheap enough to change the eight electrolytics out on the board above them even if they are still “good”.
He too is of the voice of reason of test and if good leave it but I am looking to prevent future issues and have longevity while it’s apart.
He is going to test the four big caps, which I hope/think should be fine. I figured it is easy and cheap enough to change the eight electrolytics out on the board above them even if they are still “good”.
He too is of the voice of reason of test and if good leave it but I am looking to prevent future issues and have longevity while it’s apart.
Yeah, the thing is a beast. There are also four 100v 100uf on that same board.
From what I read those big 24k caps usually don’t go bad, although with a 10w class a bias they are apparently stressed a little more than a typical ab amp?
That's why ripple current, ESR, and temperature are important specs for these.
But don't skimp on the DC voltage rating either.
But don't skimp on the DC voltage rating either.
Well, honestly speaking, most filter capacitors are sealed better, and have more electrolyte. They can last longer than the equipment.
I have noticed that filter capacitors are something like TV picture tubes of old. They are expensive and easy to change, leading many unnecessary replacements. Some NAD stuff and others have really bad filter capacitors and that drives the myth. I just saw a shorted filter cap in an SAE 2300. Unusual failure - and how old it this unit?
I would never replace signal coupling caps without good reason. It isn't easy to reform each lead, it is labour intensive. It costs money, more than the cap is worth. Therefore, most just jam the leads in, damaging the seals. You are way further ahead to leave them. Now if it is a Pioneer or other unit known for poor quality parts, sure. But expect to spend a lot on labour.
Some capacitors and other parts are worth replacing depending on temperature and run time. Again, have a good reason for replacement. "May as well" isn't a good reason.
I was authorized warranty for Adcom and know them reasonably well.
I have noticed that filter capacitors are something like TV picture tubes of old. They are expensive and easy to change, leading many unnecessary replacements. Some NAD stuff and others have really bad filter capacitors and that drives the myth. I just saw a shorted filter cap in an SAE 2300. Unusual failure - and how old it this unit?
I would never replace signal coupling caps without good reason. It isn't easy to reform each lead, it is labour intensive. It costs money, more than the cap is worth. Therefore, most just jam the leads in, damaging the seals. You are way further ahead to leave them. Now if it is a Pioneer or other unit known for poor quality parts, sure. But expect to spend a lot on labour.
Some capacitors and other parts are worth replacing depending on temperature and run time. Again, have a good reason for replacement. "May as well" isn't a good reason.
I was authorized warranty for Adcom and know them reasonably well.
Great advice and things I never considered.
So I take from your response that the Adcom stuff typically used better quality parts.
From your experience in Adcom warranty work is there anything in the GFA-5800 that I should pay attention to or should be changed while it is apart?
So I take from your response that the Adcom stuff typically used better quality parts.
From your experience in Adcom warranty work is there anything in the GFA-5800 that I should pay attention to or should be changed while it is apart?
Well, these are the "everything mosfet" stage of design. Overheated parts, normally I find Q1, Q2 cooked and no longer matched. A pain to match, you need thermal epoxy to put the heat spreader over the diff pair.
Basically, replace cooked stuff. That's it, make sure VR102 isn't intermittent due to age. They are very reliable, but like anything they age.
Basically, replace cooked stuff. That's it, make sure VR102 isn't intermittent due to age. They are very reliable, but like anything they age.