Capacitor Question

[DonaldStott]

Just a quick question hoping that someone can remind me what these capacitors are called, make, composition etc.



Values are listed in the Service Sheets.

[dazzlevision]

Originally Posted by DonaldStott

Just a quick question hoping that someone can remind me what these capacitors are called, make, composition etc.

Attachment 268395

Values are listed in the Service Sheets.

I'm pretty sure these were made by Dubilier (the UK company) and are sometimes referred to as a "bumblebee" type. The dielectric is paper, so they degrade over time and should be replaced. In the 1960s, the outer case was replaced by a grey plastic encapsulation, but they still had the curved ends (and still failed over time).

[ms660]

We used to call them rat turds, also used in some Murphy TV's amongst others.

They were failing back in the '60's when I started in the servicing trade.

Lawrence.

[DonaldStott]

Thanks to dazzlevision and ms660 - that's all the information I require.

[wd40addict]

Awful things, on the same 'change on sight' list as Hunts and easily mistaken for resistors.

[cathoderay57]

Originally Posted by wd40addict

Awful things, on the same 'change on sight' list as Hunts and easily mistaken for resistors.

Agreed, but when they're at the bottom of an Eddystone coilbox you need to be a contortionist with your soldering iron or else do quite a lot of unsoldering for access....... Jerry

[Sideband]

Originally Posted by cathoderay57

Agreed, but when they're at the bottom of an Eddystone coilbox you need to be a contortionist with your soldering iron or else do quite a lot of unsoldering for access....... Jerry

Taking the coils out helps a lot as does removing the coupling shaft to the wavechange switches. It's still a bit tight but much more do-able!

[wd40addict]

Yup, learnt the hard way on my 770R!

[G6Tanuki]

Those rat-dropping capacitors are a nightmare; I had one that was used as 'that capacitor' in an Eddystone 730/4; when it went leaky-as-a-leaky-thing-with-bullet-holes-in-it, it led to the premature death of the EL91 and its associated output-transformer.

There was also one in my Eddystone 840A. Having a 600KOhm leakage-path from the AGC line to earth is really not a path to happiness or joy.

[high_vacuum_house]

I had a load of them in a Ekco T161 television. I thought they were produced by EGEN.
Most had failed by low insulation resistance. You can replace them with the yellow axial 630V DC rated MKT1813 type capacitors by Vishay, available from the BVWS stall, RS components, Farnell ECT. They are a direct replacement and usually have a smaller size than the originals. They are a much better quality.

Christopher Capener

[Sideband]

Originally Posted by G6Tanuki

Having a 600KOhm leakage-path from the AGC line to earth is really not a path to happiness or joy.

Oh....that was a good one then! Most of the ones I've measured are only a few tens of K...or s/c!