Exploding X2 capacitor - Page 4 - UK Vintage Radio Repair and Restoration Discussion Forum

Station X · 16th Jan 2018, 9:41 pm

Quote:

Originally Posted by Station X

This evening I was using my ancient Singer electric sewing machine to repair my boiler suit. Suddenly the machine started racing and smoke came out of the foot pedal. I switched off at the wall socket, but not before it had done about six inches of unwanted stitching which will need to be unpicked.

On opening up the foot pedal, which is a very crude device, I found that a Rifa Class X Capacitor had exploded and in doing so gone short circuit. It was wired across the OFF/ON contacts which accounted for the machine not stopping when the pedal was released.

I snipped out the Rifa and all was well again. I'll replace it tomorrow.

Having replaced the Rifa, the bad news is that in "running away" the machine snapped several teeth off a plastic bevel gear. This upset the synchronisation and snapped the needle.

I have a new gear on order and fortunately have found a useful website showing how to replace it and resynchronise the machine.

Refugee · 16th Jan 2018, 10:49 pm

So that Rifa is guilty of killing a sewing machine. We need to call the capacitor police and get it jailed

turretslug · 20th Jan 2018, 3:58 pm

Maybe I should hold off applying power to this NOS 3-phase filter/rectifier panel until November 5th.... All 9 Rifas are well cracked.

Refugee · 20th Jan 2018, 4:01 pm

That looks like a jumping jack waiting to go off.

MrBungle · 20th Jan 2018, 4:05 pm

I'd turn it on outside!

Refugee · 20th Jan 2018, 4:07 pm

Defuse it first and save on cleaning the board.

Philips210 · 20th Jan 2018, 7:05 pm

Hi

The worst part of the saga has to be cleaning up the horrible mess that's often left on a PCB or whatever after the blow-up. Repacing the cap is the easy bit. That reminds me, I must check my Philips 'scope to see if it has one of the horrors installed.

Regards
Symon.

MrBungle · 20th Jan 2018, 7:18 pm

It’s pretty difficult to get off isn’t it. I would check your Philips scope. I’ve had two Philips scopes blow one of these up on me now.

Philips210 · 20th Jan 2018, 7:25 pm

Hi.

Yes, it's awkward removing the brown mess. Carefully scraping and wiping off as much as possible first before using a solvent soaked tissue or cotton bud. I've never really worked out the best thing to use for removing the mess. What is the best approach to cleaning the board etc?

Regards
Symon.

MrBungle · 20th Jan 2018, 7:31 pm

When one went off in my scope, I used IPA. I couldn’t completely clean it off if I’m honest so got the worst off mostly.

G6Tanuki · 20th Jan 2018, 7:32 pm

I've found aerosol car brake-cleaner:

https://www.screwfix.com/p/holts-aer...er-600ml/1396g

to be rather good for removing the evidence.

[Also good for removing the sticky splurges when an old-style paper-waxie "mains decoupler" capacitor has let-go]

Philips210 · 20th Jan 2018, 7:51 pm

Hi

I tried WD40 and IPA which works to an extent but I'll get hold of some of that brake cleaner which sounds to be useful.

Slightly OT but when removing the etch resist ink from a PCB after etching, I found by experiment that meths or white spirit on their own don't work well. If however they are mixed it seems to be quite good at removing the ink. What the reason for this is I don't know.

I am beginning to think the design of those caps is starting to show it's cracks.

Regards
Symon.

MrBungle · 20th Jan 2018, 7:59 pm

RS 99% IPA works nicely in etch resist. (Well marker which is what I use as etch resist anyway)

Philips210 · 20th Jan 2018, 8:05 pm

Thanks for that. I must admit to not trying IPA for the task. When I've used enamel paint for large areas of etch resist then Nitromors does the trick. I'd better get back OT.

Regards
Symon

Refugee · 20th Jan 2018, 11:14 pm

In my vacuum cleaner the air flow got rid of the worst of it.
I just needed to put the motor filter in hot water and washing up liquid.

evingar · 29th Jan 2018, 9:46 pm

Quote:

Originally Posted by evingar

Mine got replaced a few weeks ago - a mere youngster at 1999 vintage, but still had that "crazed" look about it - They often start looking crazy before they act accordingly

.... Following on from this, I mentioned to Mum (in her 80s') that hers might need checking. She replied that her Henry had actually filled the kitchen with smoke a few months back, but she left it outside to "cool off" and then continued to use it. That's the war child generation for you

On investigation, I of course found the usual foul smelling stick mess inside. !!

turretslug · 29th Jan 2018, 11:18 pm

One time, sorting out a Rifa-stricken appliance at my parents, Dad (an ex- military and civil pilot) said, "It was exactly the way Canberra cockpits used to smell"- apparently having experienced several electrical failures.

Refugee · 29th Jan 2018, 11:50 pm

Well post#75 is our second Henry to have one go off in it (smiley for pooh).

16th Jan 2018, 10:49 pm	#62
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Exploding X2 capacitor So that Rifa is guilty of killing a sewing machine. We need to call the capacitor police and get it jailed

20th Jan 2018, 3:58 pm	#63
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,394	Re: Exploding X2 capacitor Maybe I should hold off applying power to this NOS 3-phase filter/rectifier panel until November 5th.... All 9 Rifas are well cracked. Attached Thumbnails

20th Jan 2018, 4:01 pm	#64
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Exploding X2 capacitor That looks like a jumping jack waiting to go off.

20th Jan 2018, 4:05 pm	#65
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Exploding X2 capacitor I'd turn it on outside!

20th Jan 2018, 4:07 pm	#66
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Exploding X2 capacitor Defuse it first and save on cleaning the board.

20th Jan 2018, 7:05 pm	#67
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,573	Re: Exploding X2 capacitor Hi The worst part of the saga has to be cleaning up the horrible mess that's often left on a PCB or whatever after the blow-up. Repacing the cap is the easy bit. That reminds me, I must check my Philips 'scope to see if it has one of the horrors installed. Regards Symon.

20th Jan 2018, 7:18 pm	#68
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Exploding X2 capacitor It’s pretty difficult to get off isn’t it. I would check your Philips scope. I’ve had two Philips scopes blow one of these up on me now.

20th Jan 2018, 7:25 pm	#69
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,573	Re: Exploding X2 capacitor Hi. Yes, it's awkward removing the brown mess. Carefully scraping and wiping off as much as possible first before using a solvent soaked tissue or cotton bud. I've never really worked out the best thing to use for removing the mess. What is the best approach to cleaning the board etc? Regards Symon.

20th Jan 2018, 7:31 pm	#70
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Exploding X2 capacitor When one went off in my scope, I used IPA. I couldn’t completely clean it off if I’m honest so got the worst off mostly.

20th Jan 2018, 7:32 pm	#71
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,996	Re: Exploding X2 capacitor I've found aerosol car brake-cleaner: https://www.screwfix.com/p/holts-aer...er-600ml/1396g to be rather good for removing the evidence. [Also good for removing the sticky splurges when an old-style paper-waxie "mains decoupler" capacitor has let-go]

20th Jan 2018, 7:51 pm	#72
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,573	Re: Exploding X2 capacitor Hi I tried WD40 and IPA which works to an extent but I'll get hold of some of that brake cleaner which sounds to be useful. Slightly OT but when removing the etch resist ink from a PCB after etching, I found by experiment that meths or white spirit on their own don't work well. If however they are mixed it seems to be quite good at removing the ink. What the reason for this is I don't know. I am beginning to think the design of those caps is starting to show it's cracks. Regards Symon.

20th Jan 2018, 7:59 pm	#73
MrBungle Dekatron Join Date: Jun 2016 Location: London, UK. Posts: 3,687	Re: Exploding X2 capacitor RS 99% IPA works nicely in etch resist. (Well marker which is what I use as etch resist anyway)

20th Jan 2018, 8:05 pm	#74
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,573	Re: Exploding X2 capacitor Thanks for that. I must admit to not trying IPA for the task. When I've used enamel paint for large areas of etch resist then Nitromors does the trick. I'd better get back OT. Regards Symon

20th Jan 2018, 11:14 pm	#75
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Exploding X2 capacitor In my vacuum cleaner the air flow got rid of the worst of it. I just needed to put the motor filter in hot water and washing up liquid.

29th Jan 2018, 11:18 pm	#77
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,394	Re: Exploding X2 capacitor One time, sorting out a Rifa-stricken appliance at my parents, Dad (an ex- military and civil pilot) said, "It was exactly the way Canberra cockpits used to smell"- apparently having experienced several electrical failures.

29th Jan 2018, 11:50 pm	#78
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Exploding X2 capacitor Well post#75 is our second Henry to have one go off in it (smiley for pooh).