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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 22nd Jul 2020, 4:02 pm   #201
Refugee
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Default Re: Ferguson IKC2. Something went BANG!

Still it did not stir the smoke up like the vacuum cleaner did
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Old 22nd Jul 2020, 4:21 pm   #202
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Default Re: Ferguson IKC2. Something went BANG!

I wonder how many electrical appliances were binned in terror when the mains filter failed? They were used in everything including lawn mowers and just about every electrical appliance. Such a waste of good gear.
You don't know what a stink is! When you can smell a failed tripler in the porch of a customers house before you actually enter you will realize there is no comparison. Rotten eggs and sewage farms come to mind.. John.J.
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Old 22nd Jul 2020, 6:08 pm   #203
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Default Re: Ferguson IKC2. Something went BANG!

Quote:
Originally Posted by Heatercathodeshort View Post
I wonder how many electrical appliances were binned in terror when the mains filter failed? They were used in everything including lawn mowers and just about every electrical appliance. Such a waste of good gear.
My Mum and Dad binned a Kenwood Chef in such circumstances last year, I was saddened to learn. But perhaps at age 86, she just felt like she fancied a new one
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Old 22nd Jul 2020, 9:56 pm   #204
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Default Re: Ferguson IKC2. Something went BANG!

The vacuum cleaner got fixed after the smoke had been chaised out of the windows and the fire alarm had stopped screaming.
Cleaning then resumed.
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Old 25th Jul 2020, 1:50 pm   #205
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Default Re: Ferguson IKC2. Something went BANG!

They do not even need power applied.
They just split open even if NOS.
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Old 25th Jul 2020, 2:05 pm   #206
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Default Re: Ferguson IKC2. Something went BANG!

Last time I replaced one I found a Phillips computer screen fly back cap rated at 1700V.
It was a lower value but it did stop the unit making radio4 long wave crackling.
It was only about 10n.
I have seen a failed one. It just had a little melted blob on the end and was open circuit.
There was no tar deposit.
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Old 25th Jul 2020, 10:35 pm   #207
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Default Re: Ferguson IKC2. Something went BANG!

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Originally Posted by Refugee View Post
Last time I replaced one I found a Phillips computer screen fly back cap rated at 1700V.
It was a lower value but it did stop the unit making radio4 long wave crackling.
It was only about 10n.
I have seen a failed one. It just had a little melted blob on the end and was open circuit.
There was no tar deposit.
They are supposed to fail open circuit without exploding, catching fire or behave dangerously. The flyback cap might fail dangerously.

In the mid 70's Grundig and (German) ITT sets (probably others also) had a three legged cap instead of these x-rated Rifas. They were cylindric about 2 cm in diameter an 4 cm tall. They were grey or yellow radially mounted. Two of the connectors were connected together. (SC) I think they were intended to fail in a way that opened the circuit between the two shorted connectors and cut the power to the device. I had a set burn because a cap like that exploded. Anyone remember these caps?
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Old 26th Jul 2020, 1:51 am   #208
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Default Re: Beware Rifa Class X Capacitors!

Those flyback caps always had a little blob filled with carbon on the end and were open circuit with no mess on the board. They eventually made the transistor fail.
The three to five leaded filters just used to split to reveal shredded paper in the crack.
They added a bit of inductance as well as filter capacitors.
The later ones are built into the input connector and are no more reliable.
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Old 26th Jul 2020, 10:39 am   #209
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Default Re: Beware Rifa Class X Capacitors!

Those yellow 3-legged fire-bombs (if I remember correctly ITT) were a replace on sight part. After removing the back off the set you could usually smell whether it had given up, some more spectactularly than others.

The replacements were grey and seemed to be OK. Many german manufacturers used the yellow ones and we came accross quite a few charred PCBs but luckily no major fire damage.
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Old 26th Jul 2020, 8:38 pm   #210
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Default Re: Beware Rifa Class X Capacitors!

Those Grundic filter caps. The yellow ones were 220v rated, hence failure on UK 240v mains. They were an FOC replacement from Grundig as I recall. The grey replacements were 250v rated (may have beed 240v, I still have some, could check.
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Old 26th Jul 2020, 8:40 pm   #211
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Default Re: Beware Rifa Class X Capacitors!

They also failed here in Germany as regular as clockwork - on, at that time a nominal 220V~ mains supply
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Old 26th Jul 2020, 11:18 pm   #212
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Default Re: Beware Rifa Class X Capacitors!

They were said to have caused house fires and CRT implosions.
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Old 27th Jul 2020, 10:49 pm   #213
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Default Re: Beware Rifa Class X Capacitors!

If the customer had been slower with extingushing the set, he would have lost his house. Those sets burned very fast when first ignited.
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Old 27th Jul 2020, 11:07 pm   #214
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Default Re: Beware Rifa Class X Capacitors!

Hi.

Yes, I recall those 3 lead mains filter capacitors in the ITT hybrid sets CVC8-9 but don't think they were used in the earlier CVC5 but could be wrong. Virtually all the sets I came across had the later grey type fitted.
It's a long time back but I think the early ITT solid state sets such as the CVC20/30/32 may have used them too. In the hybrid sets they were located on the PCB (part of the customer control panel).
The CVC30/32 series also had a safety issue with the mains switch which is soldered to the control panel, The solder joints became embrittled posing a potential fire risk. The recommended action was to use two jumper wires from the switch to the copper print.

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Old 8th Oct 2020, 11:05 pm   #215
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Default Rifa cap nearly causes fire!

Hi All,

I dug this ASA Futura TV out of storage for a run and I left it on in the workshop when I went into the house. I got a phone call and between one thing and another I was out of the workshop for nearly an hour.

When I returned to the shed I was greeted by the usual smell and quite a bit of smoke. This didn't bother me too much as I knew what it was straight away. The TV was dead which I thought odd as the many times I've had Rifa's fail before the sets had continued to work.

When I removed the back and hinged down the chassis I was greeted by this scene. The degausing coils had caught fire! Luckily it didn't take off!

Perhaps it might not be a bad idea to check for Rifa's and similar types of caps in your equipment, I know I'll be more wary of them from now on.
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Old 8th Oct 2020, 11:44 pm   #216
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Default Re: Rifa cap nearly causes fire!

Ooh nasty. I’ve eviscerated them from everything i own. Found one in the Kenwood mixer and the Henry hoover
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Old 9th Oct 2020, 2:42 am   #217
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Default Re: Rifa cap nearly causes fire!

The ones in Henry cleaners release there smoke the fastest of all.
Mine filled the room with smoke in a couple of seconds.
It looks like a rewire for those coils.
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Old 9th Oct 2020, 8:47 am   #218
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Default Re: Rifa cap nearly causes fire!

I must confess, the lock-down & working from home has given me the opportunity to put my Portable Appliance Tester to good use, and has highlighted a number of hidden 'gems' just waiting in the wings(!)

A few surprises came through, some of my truly vintage test equipment passed with flying colours, and a couple, really didn't, and have since been addressed.

Needless to say, as Mr B has put it, I too no longer have Rifa products in my instruments or workshop equipment. These have been replaced by Wima or Kemet. I've even made an Excel spreadsheet of the gear & test results, plus labelled the 'tested/ok' items. Excessive, perhaps.

It was all many, many years overdue and has saved the smoke plumes, or in one case, a fatal injury of the equipment, or myself ... An RFI cap had gone resistive, making the whole instrument case half mains! It was only the BNC lead grounding away this 'leakage', but imagine the result had it gone short & I remove said BNC whilst holding the case and connector.

That would shift some earwax!

I've yet to address my 1960's anglepoise, the base & arm are grounded, the metal shade (where the power-switch lives), sits at just below half mains! In times passed, I've nudged the shade out of the way with my forehead, whilst working on powered sets. Eeeek, that would be a sharp'ner!

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Old 9th Oct 2020, 8:48 am   #219
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Default Re: Rifa cap nearly causes fire!

the last time I saw the degauss coils catch fire was when the client had put silver foil around the blown fuse. The posistor was arcing through and degaussing continuously. Was the burned Rifa in a similar circuit?

Luckily the plastic that TVs are made from is supposed to be self-extinguishing for just this sort of occasion!
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Old 11th Oct 2020, 3:07 am   #220
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Default Re: Rifa cap nearly causes fire!

It looks to me like the arcing/burning capacitor tried to physically set fire to the wiring of the degaussing coil. Luckily it was somewhat self extinguising, but don't count on it. ITT paper capacitors have caused house fires and were even recalled.

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Needless to say, as Mr B has put it, I too no longer have Rifa products in my instruments or workshop equipment. These have been replaced by Wima or Kemet. I've even made an Excel spreadsheet of the gear & test results, plus labelled the 'tested/ok' items. Excessive, perhaps.
Kemet is Rifa by another (newer) name. What you should do is not avoid the brand (or actually that too), but the type of capacitor. A Kemet PME will smoke sooner or later, as will a Wima MP3. Just make sure not to use paper capacitors but use polypropylene (MKP) instead.
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