Newbie needs help identifying correct capacitor replacement

[eagarcia]

Hello everyone,

I have a pair of Rokit Powered 6 RPG2 speaker monitors that I absolutely love, but on one of them, the woofer died and no longer makes a sound. I was planning on getting cheap replacements for $200, but most replacements are rear-ported which don't work well with my current set up. Instead, I took a look inside and I see all this burnt residue and one capacitor that is bulging.

I decided to buy a soldering station (X-Tronic 4010) for $40 and now I need to figure out a proper replacement for the bulging capacitor. The capacitor label says Yihcon 3300uF 50V and on the other side, it says RK 105(degree symbol)C(M) VENT.

I was looking at digikey.com but a lot of the capacitors there say things like tolerance, series, ESR, polarization, ripple current, etc., I am not sure which one to pick so that it works with my speaker monitor.

The capacitors are much cheaper than I thought, I was expecting to pay $20 for one, but it seems most of them are like $2-6, if you can recommend a premium brand that would be great.

Also, I don't have much experience in electronic repairs (I have only bought replacement parts and swap them in), the last time I did anything crazy was using a cheap eBay soldering stick to solder two 18 gauge wires together. If you can reference any great quick-start guides, I would also appreciate it.

Thanks!

 

[Wiginometry]

First from the looks of the single picture that the capacitors might not be the only thing fried.
If you have a soldering iron then you need something to decoder those parts off solder wick or a solder pump.
Post a few more pictures because you may have other parts that need to be replaced and dependent on how much damage there is you may not be able to save it...

I know that can be tough to hear but you may be able to save it to we need to see the underside of the board as well as a few more of the top of it to make any huge leaps and assumptions

 

[eagarcia]

I've uploaded two more photos, the back of the circuit and a top view of the circuit.

 

[Wiginometry]

Ok this actually looks worse than it might actually be so your first order of business would be to remove all the old destroyed parts and pieces being as careful as possible not to destroy the board take plenty of pictures along the way.

The pictures serve a few purposes to let you know what you've removed, where pieces go when you replace them, and if you have further trouble in the future.

I would honestly remove the damaged pieces prior to actually buying replacement parts just in case there is extensive damage you didn't see prior then you have wasted a bunch of money on parts you can't use.

To find out more about your pieces I would look up and/or download the data sheets on them they will be able to tell you pretty much everything about the parts in question

 

[Wiginometry]

You might also tear apart a few old computer power supplys before buying your capacitors I have quite a few that are 2200uf 105°c and that's where I scavenged them from sometimes it's worth the look but definitely get the bad pieces off the board first

Like I said sometimes the damage is just to extensive to repair it as compared to the cost of a new or used item

 

[eagarcia]

The only thing I see damaged is the capacitor, it's bulging at the top. What else are you seeing that is damaged?

Also I am asking for suggestions for a capacitor that can do the job of the old one or better, but I don't know what specifications to look for.

 

[kellys_eye]

tear apart a few old computer power supplys before buying your capacitors

You won't find one rated at 50V in a computer PSU.

Fortunately the capacitor you require is commonly available and a decent manufacturer is Nichicon as per this link:

https://www.digikey.com/product-detail/en/nichicon/UVZ1H332MHD/493-1347-ND/589088

The key numbers to recognise are:

capacitance
rated voltage
temperature range

and in your application the 105C range is noted for low ESR and the one linked to has all those characteristics.

 

[73's de Edd]

Sir / Sr . . . . . .eagarcia

Questions :
Is that unit now puttting out a low /moderate / high HUMMMMMMMMMMM . . .or . . . making more like the noise of an electric shaver running ?
Are you good enough at soldering so as to not damage the foils on the board ?
Do you have a DVM and familiarity in its use ?

Observations:
Those electrolytic cans do not particularly seem domed on their tops; nor otherwise having their purposefully weakening, cross cut depressions being split out.
Canned electrolytics other failure mode is at the exterme other end of the units , where the neophrene plug seals at their bottoms are pressurized outwardly and usually left askew / slanted in their last positioning as the presssure is vented out..
Is there being a good chance that this was being your units caps situation?
Some maunfacturers tend to use sealants / adhesives / glues on the boards . . . usually being a brownish yellow or white . . . . .whereas, yours appears to be a YUCKY black.
It is being seen piled up at 4-5 larger gauge wire connections into the board and in the center area and some other random points.

I am seeing a large power transformer to the side . . . so this is being a AC line / transformer /diode bridge supply powered unit . . . . .thereby . . . . . no more subjective to timely failure . . .switch mode power supply(s). .

Failure Modes:
You have two power supplys, with those two large caps at the edge being the ones that would create my initially mentioned heavy HUMMMM sound, while the more center of the board pair would produce the running electric shaver motor type of noise, upon their degradation / failure.

73's de Edd


.

 

[eagarcia]

Sir / Sr . . . . . .eagarcia

Questions :
Is that unit now puttting out a low /moderate / high HUMMMMMMMMMMM . . .or . . . making more like the noise of an electric shaver running ?
Are you good enough at soldering so as to not damage the foils on the board ?
Do you have a DVM and familiarity in its use ?

Observations:
Those electrolytic cans do not particularly seem domed on their tops; nor otherwise having their purposefully weakening, cross cut depressions being split out.
Canned electrolytics other failure mode is at the exterme other end of the units , where the neophrene plug seals at their bottoms are pressurized outwardly and usually left askew / slanted in their last positioning as the presssure is vented out..
Is there being a good chance that this was being your units caps situation?
Some maunfacturers tend to use sealants / adhesives / glues on the boards . . . usually being a brownish yellow or white . . . . .whereas, yours appears to be a YUCKY black.
It is being seen piled up at 4-5 larger gauge wire connections into the board and in the center area and some other random points.

I am seeing a large power transformer to the side . . . so this is being a AC line / transformer /diode bridge supply powered unit . . . . .thereby . . . . . no more subjective to timely failure . . .switch mode power supply(s). .

Failure Modes:
You have two power supplys, with those two large caps at the edge being the ones that would create my initially mentioned heavy HUMMMM sound, while the more center of the board pair would produce the running electric shaver motor type of noise, upon their degradation / failure.

73's de Edd


.

There is no hum from the woofer, in fact, it doesn't make any sound, the tweeter works fine, the speaker just sounds weird without the woofer. The black stuff is also on the other speaker pair, but it works completely fine, both woofer and tweeter. I have a multimeter and know how to read voltages on it. I don't really know about the foils on the circuit.

You won't find one rated at 50V in a computer PSU.

Fortunately the capacitor you require is commonly available and a decent manufacturer is Nichicon as per this link:

https://www.digikey.com/product-detail/en/nichicon/UVZ1H332MHD/493-1347-ND/589088

The key numbers to recognise are:

capacitance
rated voltage
temperature range

and in your application the 105C range is noted for low ESR and the one linked to has all those characteristics.

Thanks kellys_eye, I found an "audio" version of the same capacitor here, https://www.digikey.com/product-detail/en/nichicon/UKA1H332MHD/493-4614-ND/2786989

Would it be better to go with yours or the audio one? I can't really find any difference between the two other than lifetime.

 

[kellys_eye]

Those electrolytic cans do not particularly seem domed on their tops

I seem to recognise a distinct 'doming' on the capacitor not marked with a '9' (or '6').

Would it be better to go with yours or the audio one? I can't really find any difference between the two other than lifetime.

Ahhh, the 'audiophoolery' department......

If the technical specifications are the same there is zero difference other than price - the audio world seem to get away with charging double, treble....x1,000 times the cost of standard parts simply by adding 'designed for audio use' - then you are either a customer or a victim.

 

[duke37]

Measure the voltage on the capacitors and compare with the good channel, this will indicate whether the fault is in the power supply or later on.

Just work through the DC voltages.

 

[eagarcia]

Good idea duke37, thanks for the suggestion.

 

[eagarcia]

The broken one reads .5mV while the working one (same location) shows 8.9mV. I tested through the back by touching the trace(the metal lines are traces correct?) on either side where the capacitor is soldered to. Both speakers were disconnected/unpowered when I tested them.

 

[eagarcia]

I seem to recognise a distinct 'doming' on the capacitor not marked with a '9' (or '6').


Ahhh, the 'audiophoolery' department......

If the technical specifications are the same there is zero difference other than price - the audio world seem to get away with charging double, treble....x1,000 times the cost of standard parts simply by adding 'designed for audio use' - then you are either a customer or a victim.

I see what you mean, it's like those diamond HDMI cables haha. But how reliable are the datasheet numbers compared to the actual lifetime? The normal one states 1000 hours, while the audio states 2000 hours, for an extra 1.50, I can replace them half as often.

 

[eagarcia]

Here is another picture of the capacitor tops:
(forgot the flash, sorry!)


The Black stuff that is all over the circuit is some sort of glue or paste (I've seen it before in power supplies but white). Apparently whatever they use melts under heat which is why it looks all burnt. I am thinking of cleaning it out but not sure how.
Here is a photo of the black paste that is "fresh":

 

[kellys_eye]

Leave the black gunge - it's a PITA to remove and doesn't do any harm.

The capacitors look domed to me and is a typical fault symptom but the suggestion to measure at the capacitors was meant to be with the power on!

The 'hours' spec on the capacitors is a figure I find difficult to believe - if the technical spec is identical what can possibly make them differ in longevity? The printing?

 

[eagarcia]

Leave the black gunge - it's a PITA to remove and doesn't do any harm.

The capacitors look domed to me and is a typical fault symptom but the suggestion to measure at the capacitors was meant to be with the power on!

The 'hours' spec on the capacitors is a figure I find difficult to believe - if the technical spec is identical what can possibly make them differ in longevity? The printing?

Okay, I'll go with the normal ones, I don't really know the complexity of capacitors but it sounds they are simple devices.