Small 4700uF 35V caps

[ppppenguin]

I'm fixing a pair of M-Audio AV-40 nearfield monitor speakers that I was given. The fault is buzz and hum. The amps are in one speaker, the other is passive.

Opened up the active speaker. It's immediately obvious what's wrong. The main smoothers (4700u, 35V) are bulging, as are 2 other 220u 25V caps. I've got plenty of 220u caps but the 4700u are a problem. They are only 20mm diameter and 26mm high. Made by "mtdcon". I don't think I've got more than 1mm spare for diameter.Absolute max height is 30mm though I might be able to finesse a little more by cutting holes in a shield plate.

The other hassle is that everything is glued down to stop it being shaken by the speaker. A nuisance but I can deal with it.

There's nothing in the RS catalogue. I don't think I could squeeze in these: https://uk.rs-online.com/web/p/aluminium...s/8752582/ Can't see anything in the Farnell catalogue either.

Any ideas?

PS: These might work. On a slow boat from China and utterly unknown quality. https://www.amazon.co.uk/Quality-Aluminu...2?dchild=1&keywords=4700uf+35v&qid=1609266568&s=diy&sr=1-2

PPS: These 3300uF will fit. I'll try some odd caps and see if it's enough: https://uk.rs-online.com/web/p/aluminium...s/0571379/

[Nick]

https://uk.farnell.com/united-chemi-con/...361?st=35V

USA stock, so expensive...

[ppppenguin]

And on back order too. Not worth it. Mouser or Digikey might have something but it's not worth making the order up to the free delivery minimum.

I'll try a couple of 2200u tomorrow and see how it works. Then add some 1000u in parallel if necessary. If it's all OK I'll get some 3300u from RS.

[Murphyv310]

Hi.

I'm not promising but I'll get a look tomorrow and if I've got one or two I'll pop them in the post Jeffrey.

[ppppenguin]

Many thanks, Trevor.

[Crackle]

And on back order too. Not worth it. Mouser or Digikey might have something but it's not worth making the order up to the free delivery minimum.

I'll try a couple of 2200u tomorrow and see how it works. Then add some 1000u in parallel if necessary. If it's all OK I'll get some 3300u from RS.

Dont forget that RS and Farnell both have a minimum order value for free delivery.
Mike

[ppppenguin]

I've replaced the 220u caps and tacked in some (physically oversize) 2200u to see how it works. There's a faint background hum, audible with ear pressed to speaker. Using 4700u makes no audible difference. It's the sort of hum that I can't really see on the 'scope at 20mV/div at a x10 probe tip. I could hook up a direct conenction to the scope to give me 2mV/div but don't think it's worth the effort.

All the lower value will do is reduce the maximum power output slightly. This doesn't matter. So I'll get some 3300u caps.

Trevor, thanks for your kind offer but it's quicker and easier for me to order from RS.

I still have a trade account with RS so I get free delivery for all orders.

[Murphyv310]

No problem Jeffrey.
I didn't have a small 4700uf but I do have small 2200uf at 35v.

[ppppenguin]

Thanks for looking. With a bit of luck, my RS order should come tomorrow with 3300u caps. Ordered a few other bits too and ended up spending about £50

[Mark Hennessy]

That's what always happens to me, too. Partly because I feel a bit guilty taking advantage of the free delivery for small orders that I also get from RS

Mouser was mentioned earlier. I placed an order with them about 4 months back, and was extremely impressed with their service. Delivery time was only 2 days, which I think is pretty good. Their minimum order for free delivery was £33 - I assume it's still the same, but haven't checked recently. To make that up, I ended up ordering a few parts that I couldn't find in RS or Farnell - actually, I was pleasantly surprised at how wide their stock was in those areas compared to the UK regulars. Prices were excellent too. I anticipate using them a lot more in future.