Capacitor identification "RS"

[JellyBelly]

Hi I am looking to replace these capacitors in a Rogers HG88 MK11. I have looked at the schematic (which doesn't match very well with reality) and it suggests they are Electrolytic?? I found a thread about capacitors which mentions these but does not state what type they are.

[Station X]

Hello and welcome to the forums.

Those don't look like electrolytic capacitors to me, as they have no polarity markings.

Is there a value in uF or pF written on them somewhere?

[ms660]

Dubilier made for RS, poss. mixed film type.

Lawrence.

[bikerhifinut]

What makes you think they need replacing?
A quick butchers at the photo suggests they may already have replaced some original capacitors as the resistors underneath look to be more modern carbon films compared to the other resistors there which look like Erie ceramic body jobs and carbon composition stuff.

I can't be certain on this but I think those grey RS jobs were early plastic film jobs, and if so will be likely to be still OK.
I could be mistaken however as there were some plastic body caps that had old style paper in oil innards.

I haven't got a circuit diagram to look at so someone else with a working knowledge of the HG88 will no doubt enlighten us.

Andy

[JellyBelly]

different values 0.022, 0.047, 0.1 uf all 600v

[JellyBelly]

I not sure they need replacing depends on what type they are. i found some on ebay which say they are MD, which could mean Mixed Dielectric ??

[bikerhifinut]

They will most definitely not be electrolytics at those small values.
OK well IF they really are in need of replacement and if plastic films its unlikely but I'll assume they are faulty, then just go and get any plastic film capacitor (Polyester, polypropylene) rated at 630V as being the nearest commonly found working voltage to 600 in modern values.
None of them are odd values so you'll get them at any of the regular component suppliers.

I'll repeat the original question however, what's the fault that suggests these capacitors are faulty?

A.

[vidjoman]

My HG88 had Mullard Mustards as originals. Someone has already changed these for the RS ones. Probably was unnecessary as the Mullards rarely fail even after nearly 60 years.

[JellyBelly]

all are 600v 0.022uf 0.047uf and 0.1uf
so could be replaced with standard polyester film capacitors?

[Nuvistor]

Originally Posted by ms660

Dubilier made for RS, poss. mixed film type.

Lawrence.

Agree mixed dielectric, paper and film, very often leak like paper type but worth testing on rated voltage before replacing.
RS ones were grey, Dubilier blue/white or blue/yellow.

[DMcMahon]

Originally Posted by JellyBelly

Hi I am looking to replace these capacitors in a Rogers HG88 MK11. I have looked at the schematic (which doesn't match very well with reality) and it suggests they are Electrolytic?? I found a thread about capacitors which mentions these but does not state what type they are.

Quickly looking at one lot of documentation, the schematic and parts list correctly identifies the capacitor types, i.e. only electrolytics are shown/listed as electrolytic.

The ones in question which I assume are coupling capacitors are listed as Paper, so it does look like the RS ones are not the originals.

David

[Radio Wrangler]

They are certainly not electrolytic ones.

They are in a place where paper or plastic film types will be fine, and the ones there may not be the original ones.

Paper capacitors suffer from the slow ingress of moisture from the air, making them progressively, electrically, leaky. It can take many years in better quality parts.

You'll get mixed advice, depending on where and who you ask. On this forum the general consensus is to test capacitors and replace if necessary, although there are several types known to be troublesome and worth changing on sight. On many hifi fora, you'll see the word 'recapping' and they'll advise you to swap every capacitor in the thing and possibly for several feet around it. Doing this all in a oner without testing as you go has a track record of introducing new faults, scattered around the unit. On high-end audiophile fora, the advice is usually to replace them all, but with special audiophile boutique grade parts at eye-watering prices.

Replacing parts isn't risk-free. Other things are stressed in soldering and freeing wire leads from tag strips or PCBs. This is the reasoning behind people asking you why you've decided to change them.

David

[JellyBelly]

Quickly looking at one lot of documentation, the schematic and parts list correctly identifies the capacitor types, i.e. only electrolytics are shown/listed as electrolytic.

The ones in question which I assume are coupling capacitors are listed as Paper, so it does look like the RS ones are not the originals.

David[/QUOTE]

hi David do you have a good quality schematic for this amp as the one i have is very blurred, or my eyes dont work so well!!

[JellyBelly]

Hi Graham
thanks for the welcome. a quick question, when someone replies to my post i dont get any notification, is that normal?
thanks

[DMcMahon]

No do not have a good quality schematic, the one in Post # 4 of this linked thread is the best of several that I have seen.

https://www.google.com/url?client=in...DEj0i5sIUaOHSO

The Mk. III schematic (similar to the Mk. II) from Post # 2 of this thread is quite good.

https://www.google.com/url?client=in...N5sJkvVXdyOPnx

David

[vinrads]

I would be replacing both capacitors and the 220k anode load resistors , for low noise ones ,Mick.

[barrymagrec]

I've no idea how these caps which I remember as "mixed dielectric" age, but when used as mains snubbers back in the seventies they failed short circuit frequently - and yes, they were the wrong type of cap for that purpose.

[Cobaltblue]

Originally Posted by JellyBelly

Hi Graham
thanks for the welcome. a quick question, when someone replies to my post i dont get any notification, is that normal?
thanks

You will only get a notification if you subscribe to the thread.
You will find the subscribe options in "additional options" when you post.

Cheers

Mike T

[dazzlevision]

Originally Posted by barrymagrec

I've no idea how these caps which I remember as "mixed dielectric" age, but when used as mains snubbers back in the seventies they failed short circuit frequently - and yes, they were the wrong type of cap for that purpose.

That’s true, but UK mixed dielectric types (from TCC, Dubilier and Hunts in the main) such as these were the only ones generally and economically available to UK consumer electronics manufacturers.

[David G4EBT]

I've just thrown away 200 of those grey RS 600V 0.1uF capacitors.

They were 'New Old Stock' and though I'd had them for some years (no doubt a rally purchase), they looked brand new. I'd intended to offer them on the forum if they tested OK for capacitance and leakage. I'd assumed that as they were branded 'RS' that they'd be good quality. However, their values were all over the place from .05 to 0.5 uF. Having tested twenty and not finding one that measured 0.1uF, I binned the lot.

It could of course be that they were out of spec rejects rather than simply surplus stock when sold on a rally stand, so I wouldn't want to imply that they're all dodgy, but if I came across them in equipment, I'd want to lift one end and check to be sure.