Cap ID Question with Photo

[seventy1]

Hi, I'm putting together a BOM to order parts to recap a Sony CDP-508ESD and need help identifying a capacitor in the PS circuit. It's a 47uF 5.5v Nichocon JB H8912 85C, measuring 18.5 x 40 with 7.5mm lead spacing. I'm confused because it's so large for a low value, low voltage cap. I need to go to 50v to find one with the same lead spacing. The rest of the caps on this 1980s vintage CD player are normal. Is this a special purpose part? Thanks!

 

[gadget73]

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wild guess, it might be a "supercap", one of those super low leakage things used as the memory power supply for the unit to hold settings.

 

[Leestereo]

...It's a 47uF 5.5v Nichocon JB H8912 85C, measuring 18.5 x 40 with 7.5mm lead spacing. I'm confused because it's so large for a low value, low voltage cap. I need to go to 50v to find one with the same lead spacing...

@gadget73 is correct, Nichicon JB series capacitors are for memory back-up: https://www.mouser.com/datasheet/2/293/nichicon_e-jb-1187159.pdf. Note the capacitance is 47mF not 47µF.

 

[seventy1]

Thanks @gadget73 and @Leestereo (I fixed the photo, I think).

Note the capacitance is 47[B][I]m[/I][/B]F not 47[I][B]µ[/B][/I]F.

This confused me too. Google search found: "Technically ‘mfd’ represents ‘milliFarad’ while ‘uF’ stands for ‘microFarad’ which is an order of magnitude smaller. Here is where the confusion begins. Some older capacitor manufacturers used ‘mF’ in place of uF on their capacitors. Whether it was because their machines could not imprint the correct symbol ‘µ’ or for another reason not known to us, this was the common practice." The data sheet you found clears it up, it's really 47 milliFarad, or 47,000 microFarad. I'm glad you clarified!

 

[seventy1]

So, after a quick look, I don't see a replacement for these "supercaps". The Nichicon obsolete part replacement sheet doesn't have a substitute. Since the memory backup isn't that important to me, do I just go with a a 47K uF power supply cap?

There's nothing close. This Nichicon is a 47K uF but is 30mm in diameter and has 10mm snap-in leads. I'd have to add leads to get to the 7.5,, spacing, then somehow secure it to the PCB. Should I just reuse the old part if it checks ok? The transformer has a hum, so I wanted to replace the power supply caps.

 

[elnaldo]

I think you need to search for a "super capacitor", not a regular capacitor. They are very common nowadays, some of them come in a "coin" format, flat with 2 solder tabs similar to a computer battery. I think to match capacitance is not relevant. A larger capacitor will take longer to discharge.

I've seen 2 caps in series, to add voltage rating, since this super caps use to come in low voltages (like 5V)

https://www.mouser.com/Passive-Components/Capacitors/Supercapacitors-Ultracapacitors/_/N-5x76s

 

[seventy1]

Ok, I did find them with a super capacitor search, thanks @elnaldo ! But still nothing interchangeable. The closest I find is a Kemet (below), but it has 5mm PC pin mount spacing vs. the original's 7.5mm through hole. If all this capacitor does is provide memory power for the programming feature, which I'd never use and appears to work with the old capacitor, do I really need to replace it? Is there any way this could affect the sound or function, outside of memory?

 

[gadget73]

if it shorts it might cause some trouble in the power supply that might make it go stupid. Honestly I'd be inclined to leave it be if you can't find sub. Worst case, I have bent leads to make things fit pcb spacing other than what the component was intended for.

as for the olden days with "mfd" meaning microfarad, a lot of that dates to the tube era. Through the 60s at least it just wasn't common in the US at least to use them funny lookin letters. Once components from Japan with the funny letters became common, then it was odd if you were using "M" instead of the mu. Really old US schematics will have caps in mmfd too, micro-microfarad. Now we'd call that picofarads. I've also seen things with M for one thousand, so a 1M resistor is 1,000 ohms. M being the Roman 1000. That basically died by 1930 or so.

 

[elnaldo]

This 2, ELNA DB and DBN series are 47000uF (As said, if you install a larger capacitor, it will hold the charge for longer, I don't think there will be any ill effect doing this, current is usually limited by resistors, but of course I can't be 100% sure from here)

(EDITED: datasheet says 5mm spacing)

https://mouser.com/Passive-Componen...apacitors/_/N-5x76s?P=1z0wqf2Z1z0z7l5Z1z0x0jw

At $2.20, I'd replace it if you are doing other maintenance to the unit, the capacitor is 30 years old, and those super capacitors can leak, I haven't seen all the caps in the world, but I've seen already 3 units damaged by supercapacitors leakage (Technics SU-V4X, Technics PX111 electrical piano, severe PCB damage, and another unit I don't remember now)

 

[seventy1]

Thanks, good advice. I already hit the order key but I’ll add this to the next one. Mouser appears to have a larger selection than DigiKey...

 

[MK II]

Hi guys,
I was after replacement of the Duorex leaking caps on CDP-X33ES. Before hand i had an issue with my right channel anytime after the player sits for a while and basically that channel wasn’t giving a clear sound. So after caps upgrade on every red elna, even it wasn’t leaking(90% of these were), i still had the same issue after. So i went back to the board to chase it up. My tester gave indication of faulty 5.5v as mentioned. So took it off but had no other one to put in. As discussion goes that cap is Nichicon 5.5v 47mF, JB series, H8942, 85’ C. Instead i wacked in a 450v 47uF just for quick test and that issue has gone, both channels sound crystal clear now. I am looking to get replacement but is a bit difficult to find cheap in UK hardly in ebay. To comlete, in my case looks like it is not just the memory relating cap.

 

[elnaldo]

Those large capacitors are usually memory backup capacitors, I don't know of any other use in an audio amplifier for such a large capacitance.

I wouldn't buy capacitors from ebay. Seach for supercapacitors at any known supplier in your country, they are very common. The shape is not relevant as long as you can fit it in your PCB. Just don't go to a lower voltage. Stay with 5.5V or higher.

 

[MK II]

Those large capacitors are usually memory backup capacitors, I don't know of any other use in an audio amplifier for such a large capacitance.

I wouldn't buy capacitors from ebay. Seach for supercapacitors at any known supplier in your country, they are very common. The shape is not relevant as long as you can fit it in your PCB. Just don't go to a lower voltage. Stay with 5.5V or higher.

Thanks for making it clearer buddy. I might pop up to RS Components, believe they should find replacement for me. Cheers