Capacitor ratings

Anything to do with New Zealand Classic or Vintage Computing not covered in the other forums

Capacitor ratings

Postby Clym5 on Fri Jan 30, 2015 7:49 pm

I've come across some X2 main filter caps in some old gear, but I can't figure out the damn rating on it! It's a "1.0K 280V X2 MPP" Metallized Polypropylene I guess would be the MPP bit.

Anyone here have any clue what the rating might be in uF or nF? I have a suspicion that it might be 1 uF.
Amiga 4000: Apollo Turbo 040, 128MB Fast, 40gb HDD, CD-ROM (needs internet)
C64: 1541U-II, MixSID, WiFi, LumaFix64
ZX Spec, A1200, CD32, MacPlus/SE, A500, BBC Turbo Master (NASA), 2600, Acorn 4000, VIC-20, IBM 5155, GameBoy
Clym5
 
Posts: 284
Joined: Tue Jul 08, 2014 5:23 pm
Location: Meadowbank, Auckland

Re: Capacitor ratings

Postby RonTurner on Fri Jan 30, 2015 9:21 pm

Look for where is has a number followed by uf or nf those numbers quoted in above post are not the value.

If you want to see it explode plug in the device and wait, about 5 minutes should do it...

Most people will get real scared when they see the magic smoke genie released from a computer, but i have had them blow up then I just open a window and carry on copying a disk or whatever I was doing.

In fact when bidding on a computer on Trademe I actually prefer the seller says "plugged it in, 5 minutes later a bang and cloud of smoke" that way I can get it cheaper.
RonTurner
 
Posts: 339
Joined: Tue Dec 17, 2013 9:43 pm

Re: Capacitor ratings

Postby Clym5 on Fri Jan 30, 2015 10:04 pm

Sadly, those were the only markings. No mention of uF or nF anywhere. I've heard of the K rating before, but I can't seem to find how to convert it.

I'm not worried about filters exploding, but the unit doesn't work without this, oddly enough.
Amiga 4000: Apollo Turbo 040, 128MB Fast, 40gb HDD, CD-ROM (needs internet)
C64: 1541U-II, MixSID, WiFi, LumaFix64
ZX Spec, A1200, CD32, MacPlus/SE, A500, BBC Turbo Master (NASA), 2600, Acorn 4000, VIC-20, IBM 5155, GameBoy
Clym5
 
Posts: 284
Joined: Tue Jul 08, 2014 5:23 pm
Location: Meadowbank, Auckland

Re: Capacitor ratings

Postby RonTurner on Fri Jan 30, 2015 10:38 pm

The number is on the top, not the side if its one of those yellow blocks.

So you removed the filter and it stopped working ? I havent heard of that before, I have had no trouble powering up computers after removing the filters before ?

I dont see how this unit could rely on an A/C filter as it has no effect on voltages etc, just clamps spikes in the power.
RonTurner
 
Posts: 339
Joined: Tue Dec 17, 2013 9:43 pm

Re: Capacitor ratings

Postby Clym5 on Sat Jan 31, 2015 1:18 am

Ah, alright. The component is mounted in such a way that obscures the view of the top of it. The other caps have "Carli" on top, but that's it. I'll have a look at the top of it later this morning.

The filter is still in the circuit, but it is bulging and smells bad when powered up, but the device no longer works. Everything else seems to be fine. Maybe it went open-circuit?
Amiga 4000: Apollo Turbo 040, 128MB Fast, 40gb HDD, CD-ROM (needs internet)
C64: 1541U-II, MixSID, WiFi, LumaFix64
ZX Spec, A1200, CD32, MacPlus/SE, A500, BBC Turbo Master (NASA), 2600, Acorn 4000, VIC-20, IBM 5155, GameBoy
Clym5
 
Posts: 284
Joined: Tue Jul 08, 2014 5:23 pm
Location: Meadowbank, Auckland

Re: Capacitor ratings

Postby RonTurner on Sat Jan 31, 2015 9:55 am

Clym5 wrote:Ah, alright. The component is mounted in such a way that obscures the view of the top of it. The other caps have "Carli" on top, but that's it. I'll have a look at the top of it later this morning.

The filter is still in the circuit, but it is bulging and smells bad when powered up, but the device no longer works. Everything else seems to be fine. Maybe it went open-circuit?


Its not the filter causing the problem, the filter will not go open circuit, it sounds like its ready to blow which is perfectly normal for old filters.

Sounds like the device is faulty and more significant issues else where preventing it from working.

Filters have hard shells that cannot bluge, they crack open and sometimes violently,

I have experienced dozens of filter failures, there can be a loud crack or a tinny pop but always followed by a big cloud of stinky smoke, not one device stopped working during or after failure, they also powerup fine when the filters are simply removed.

Filter caps dont have polarity.

Filters appear next to the power plug before other components and join the two live A/C wires.

You can remove the filter and still power up the device, not all computers have them, for example the system 80.

You may find its 0.01 uf and 0.47uf if its larger.

Take precautions to protect your eyes when close to the device, lids off and your powering up....
RonTurner
 
Posts: 339
Joined: Tue Dec 17, 2013 9:43 pm

Re: Capacitor ratings

Postby arjoll on Sat Jan 31, 2015 10:10 pm

Clym5 wrote:I've come across some X2 main filter caps in some old gear, but I can't figure out the damn rating on it! It's a "1.0K 280V X2 MPP" Metallized Polypropylene I guess would be the MPP bit.

K will be the tolerance. I'd expect that the value of this component is 1.0 uF, 10% tolerance.

The value will either be three numbers - two significant digits and a number of zeros, such as 104 = 100000pF = 100 nF = 0.1 uF - or a directly written value. In this case it sounds like a value, which is most common on all the X2 caps I've come across - and from the application microfarads is most appropriate. 1.0 uF seems a little higher than normal, but it depends on the application.

Smaller caps, such as ceramics and polyesters, usually use the three number code.
'arjoll' on Trademe
Wishlist: BBC model B, Spectrum 48k and anything Sord.
arjoll
 
Posts: 109
Joined: Thu Apr 02, 2009 7:27 pm
Location: Invercargill

Re: Capacitor ratings

Postby arjoll on Sat Jan 31, 2015 10:22 pm

RonTurner wrote:Its not the filter causing the problem, the filter will not go open circuit, it sounds like its ready to blow which is perfectly normal for old filters.

They do generally fail open circuit. They self-heal to a degree from over-voltage, but the failure mode we're all familiar with on the RIFA caps is gradual moisture build up in the paper dialetric caused by breakdown of the epoxy case. They start acting more like a resistor, the cap heats up, the moisture wants to escape, but the resin is still usually intact enough to create a pressure build-up. On the final breakdown and loss of magic smoke they split open and fail open circuit - anything else and you'd have a far more violent end, and probably blackened pins on the mains plug and a tripped MCB or fuse!

RonTurner wrote:You can remove the filter and still power up the device, not all computers have them, for example the system 80.

It's possible to run without one, but probably best to reinstate it when you can. Snip the old one out as soon as you can though - they fail open circuit but it's never good to have any kind of damaged component across the mains.

I'd expect most switchers to have them for EMC - does the System 80 have a linear supply?

RonTurner wrote:You may find its 0.01 uf and 0.47uf if its larger.

Most are, but the one quoted is 1.0 uF. Replace like with like - the value would have been chosen to match the rest of the power supply, there will be a time constant which provides best suppression of whatever hash the supply wants to shove back into the mains.
'arjoll' on Trademe
Wishlist: BBC model B, Spectrum 48k and anything Sord.
arjoll
 
Posts: 109
Joined: Thu Apr 02, 2009 7:27 pm
Location: Invercargill

Re: Capacitor ratings

Postby Clym5 on Mon Feb 02, 2015 5:20 pm

Is it possible to replace this X2 filter cap with a regular MPP type cap of the same values? I usually do, but I've never come across one of the X2 type.

I'll get a 1 uF one, as everything seems to suggest it is. The bulging isn't too much, but there is a noticeable lump, and browning where it is. Nothing else seems too out of spec or damaged. Oh well, we'll see!

Thanks for the help!
Amiga 4000: Apollo Turbo 040, 128MB Fast, 40gb HDD, CD-ROM (needs internet)
C64: 1541U-II, MixSID, WiFi, LumaFix64
ZX Spec, A1200, CD32, MacPlus/SE, A500, BBC Turbo Master (NASA), 2600, Acorn 4000, VIC-20, IBM 5155, GameBoy
Clym5
 
Posts: 284
Joined: Tue Jul 08, 2014 5:23 pm
Location: Meadowbank, Auckland

Re: Capacitor ratings

Postby arjoll on Mon Feb 02, 2015 8:54 pm

Clym5 wrote:Is it possible to replace this X2 filter cap with a regular MPP type cap of the same values?

Possible? Yes. Wise? No. X2 caps are designed to be fitted across the mains - they are designed to cope with minor surges, self-heal after small overloads, and are designed to fail open-circuit. You might get away with something else, but X2's aren't expensive. If you really, really want to use something else then derate the voltage - don't go lower than 630 V, and potentially put in a 1 kV part.

X2's shouldn't be expensive. I see Jaycar don't do 1 uF, but they do a 470nF (0.47 uF) so you could two in parallel. Element14 have a Panasonic at $0.59+GST - there might be cheaper, it was just first on the list when I searched! http://nz.element14.com/panasonic-elect ... dp/1198302
'arjoll' on Trademe
Wishlist: BBC model B, Spectrum 48k and anything Sord.
arjoll
 
Posts: 109
Joined: Thu Apr 02, 2009 7:27 pm
Location: Invercargill

Re: Capacitor ratings

Postby Clym5 on Mon Feb 02, 2015 9:11 pm

arjoll wrote:don't go lower than 630 V, and potentially put in a 1 kV part.


Could the fact that it is 280v be the reason it failed? It isn't extraordinarily old.
Amiga 4000: Apollo Turbo 040, 128MB Fast, 40gb HDD, CD-ROM (needs internet)
C64: 1541U-II, MixSID, WiFi, LumaFix64
ZX Spec, A1200, CD32, MacPlus/SE, A500, BBC Turbo Master (NASA), 2600, Acorn 4000, VIC-20, IBM 5155, GameBoy
Clym5
 
Posts: 284
Joined: Tue Jul 08, 2014 5:23 pm
Location: Meadowbank, Auckland

Re: Capacitor ratings

Postby arjoll on Mon Feb 02, 2015 9:34 pm

Clym5 wrote:Could the fact that it is 280v be the reason it failed? It isn't extraordinarily old.

If it was X2 - no, that's a normal rating. If it wasn't X2 then yes.
'arjoll' on Trademe
Wishlist: BBC model B, Spectrum 48k and anything Sord.
arjoll
 
Posts: 109
Joined: Thu Apr 02, 2009 7:27 pm
Location: Invercargill

Re: Capacitor ratings

Postby Clym5 on Mon Feb 02, 2015 9:58 pm

Ah, I see. Thanks for the help Ron and Arjoll!
Amiga 4000: Apollo Turbo 040, 128MB Fast, 40gb HDD, CD-ROM (needs internet)
C64: 1541U-II, MixSID, WiFi, LumaFix64
ZX Spec, A1200, CD32, MacPlus/SE, A500, BBC Turbo Master (NASA), 2600, Acorn 4000, VIC-20, IBM 5155, GameBoy
Clym5
 
Posts: 284
Joined: Tue Jul 08, 2014 5:23 pm
Location: Meadowbank, Auckland

Re: Capacitor ratings

Postby RonTurner on Mon Feb 02, 2015 10:53 pm

Im betting on 0.47uf and 0.1uf
RonTurner
 
Posts: 339
Joined: Tue Dec 17, 2013 9:43 pm


Return to General

Who is online

Users browsing this forum: No registered users and 2 guests

cron