Potentially Dangerous Vintage Capacitor?

[Lee Majors]

A technician (with his soldering iron) hit the original Oil & Paper capacitor in the power supply of my Technics 1200 mk2 Turntable. It looks like a snubbing circuit capacitor/noise suppression? rated 0.047uF 450V, Orange Panasonic most likely from the 80's.

His response was it is just cosmetic and there is nothing to worry about. However, I'm not filled with confidence as it is in the AC power section....

Can anyone help me out and can confirm its safe? He hasn't tested it, so I'm not sure how he would 100% know. I am nervous it could fail at some stage.

Please see images

[redwire]

Re: Potentially Dangerous Vintage Capacitor?

That cap is across the power switch, to lessen arcing and loud pops in loudspeakers.
So if it fails short-circuit, the TT just stays on. And there is a fuse too.
It's not an electrolytic - so hydrogen generation and kaboomski not going to happen.
It's not directly across mains like modern SMPS equipment, a Rifa kind of situation where there is lots of energy available and unsafe results.

If it really bugs you, just put in a modern PP safety film cap. That's what I did on a few old TT's when I recap them.
I know the old Marcon oil caps do go low value, and usually fail short in oscilloscope HV sections, but no mess or anything.

I stay away from techs that can't drive a soldering iron lol. They can touch belts, cables, cords etc. and cause a lot of damage.

[petehall347]

Re: Potentially Dangerous Vintage Capacitor?

i would ne more concerned over the poor wiring for example the soldered wire wrap pin etc.

[Lee Majors]

Re: Potentially Dangerous Vintage Capacitor?

Hi Redwire

Thanks for your knowledge. So, ok great so it's like a suppression safety capacitor, that is very helpful. I did see this category of capacitors when looking for a replacement on elements14.

I would just like to add that the Technics 1200 mk2 is quite unusual for a vintage turntable as the signal path is completely isolated from the main board or any other electronics. The tonearm from the stylus tip to the RCA outs are completely decoupled. So I assume it is more of a safety suppression cap and voltage transients, as you mentioned for a replacement. Please see a small section of the schematic in question.

I ended up getting a snubbing capacitor yesterday, maybe the wrong choice.... but I think it would work, no? Possibly a little overkill hehe.

Here in Australia mains are 240V 50Hz

CORNELL DUBILIER 940C20S47K-F
940C Series
Double Metallized PP
47000pF
Snubber
630VAC / 2kV VDC
dv/dt Rating 1.712kV/µs
RMS current 5.2A


And yes the soldering iron skills were eye-rolling, left me some nice scrap metal souvenirs as well. Drops and shards all over the place. Some stuck to the transformer primary leads as well. Classy.

[Lee Majors]

Re: Potentially Dangerous Vintage Capacitor?

Petehall, Now that I look again, you might be right. The original had far more wraps around the terminal..... Solder breaks loose and yeah, I am Djing with my hair on fire! Literally :-/

[stj]

Re: Potentially Dangerous Vintage Capacitor?

as usual the japanese used the wrong fuse.
for 230v you should use ceramic not glass - so it doesnt break if it blows.

does the mk2 still have phono cables sticking out instead of fixed sockets?
i allways hated that about the original 1200's

[Lee Majors]

Re: Potentially Dangerous Vintage Capacitor?

Ceramic hmmm, Ok I will have to investigate this. A new rabbit hole to actively pursue. However, I'm sure the Japanese models didn't even have a fuse. The Australian market models have the glass fuse as you can see.

As for the phono cables, they are soldered directly to a PCB board within the tonearm base, alongside the tone-arm wires coming directly from the cart connection (service socket) the RCA's go through a strain relief which is fixed into an aluminum base plate that is screwed into the main chassis.

So if I understand you right, there are no socket outputs to use your own favorite RCA HIFI cables. There are wire harnesses available though from origin live and KAB that allow one continues silver wire signal path from the service socket in the tone-arm to the RCA pin end.

The sound absolutely AMAZING!

[eccerr0r]

Re: Potentially Dangerous Vintage Capacitor?

F2 is okay go be glass, that's low voltage. I couldn't see F1 which was just cut off the picture, which should be a ceramic fuse for 220V so it won't explode if it blows.

Incidentally I had one of those 5mm x 20mm 10A fuse in 120V blow. It didn't explode but it splattered a lot of crap inside the glass enclosure, I suspect it would be a lot worse at 220V ...

[stj]

Re: Potentially Dangerous Vintage Capacitor?

10a is rare in 20mm, most company's only make 20mm upto 6.3a for safety.

but the japanese being 100v always put 20mm glass fuses in everything.
every japanese audio device i repair has glass in it.
they also like to wire-wrap or crimp-nut the mains cables instead of soldering!!!

you can pull that shit with 100v but you shouldnt be doing it at 220-250!
in japan most houses arent even earthed - thats why their audio gear isnt either - they just put the optional ground-screw on the back.
i assume in japan they just use it to common the stack together.

[Lee Majors]

Re: Potentially Dangerous Vintage Capacitor?

You can see here

[Lee Majors]

Re: Potentially Dangerous Vintage Capacitor?

I saw EEVBLOG guy talking about how some caps can take on moisture and fail. Does anyone believe this, and if so wouldn't it be more of a possibility with this damaged insulation cap? hmmmm

[stj]

Re: Potentially Dangerous Vintage Capacitor?

caps that take on moisture are paper ones.
either ancient wax coated ones from valve equipment, or the infamous epoxy cased RIFA caps.
i'm pretty sure the one in your deck is not paper - probably polypropylene.

[stj]

Re: Potentially Dangerous Vintage Capacitor?

just looked it up.
not saying it's true, but some audiophile dick says that series is "paper in oil in ceramic tube"
so if it's got a ceramic case under the sleeve your o.k.

it's a +/- 20% rated cap so nothing special - although the audiophools think they are worth silly money!

[Lee Majors]

Re: Potentially Dangerous Vintage Capacitor?

Yes just had a look at those RIFA caps. Like wow! They totally explode and shatter into 1000 pieces. Crazy!

So I have 2 service manuals and 1 lists the cap as oil and paper, to which I tend to believe. I have seen many others almost identical and of the same color caps from vintage Japanese stuff from the 80's. The supplement manual says polyester. The latter polyester ones I know well and they look much different. They are a brown Radial cap shaped like kidney bean.

The ones in mine have like a plastic cover/sleeve with some white material underneath. Maybe the guy is right. And from what you are saying i should be right, which is a relief to know. You have been very helpful. Thank you.