Capacitor Shield ?

[jurb...@gmail.com]

https://dl.dropboxusercontent.com/u/29948706/KR-4070%20Caps.jpg

In a Kenwood receiver. It is steel, not aluminum.

What is its purpose ?

[M Philbrook]

In article <4395ae50-6c53-4fa3...@googlegroups.com>,
jurb...@gmail.com says...

>
> https://dl.dropboxusercontent.com/u/29948706/KR-4070%20Caps.jpg
>
> In a Kenwood receiver. It is steel, not aluminum.
>
> What is its purpose ?

Not sure, I don't think it's being used a Mu metal, cause
I don't see anything alarming there?

It could be there to enclose the rupthure if the caps
explosed I guess ? Who knows. :)

Jamie

[Mark Zacharias]

"M Philbrook" <jamie_...@charter.net> wrote in message
news:MPG.30a5d74ea...@news.eternal-september.org...

What was the original question?

Mark Z.

[Michael Black]

"Capacitor shield?"

At least, that was in the subject header.

Michael

[Jeff Layman]

And, whatever it does, why is it asymmetric?

--

Jeff

[N_Cook]

Is there any trace of someone having been in there before?
On the extended part of the "U" , into the large heatsink, is there a
purpose made anchor point there also ?
A part left over, buggered if he could remember where it came from, but
thought it best to leave it inside somewhere, JIC.
Haven't we all been there at sometime , with odd bits of metal work?
On that front I picked up one of those dash-board cam gizmos last week ,
with 1 second spaced stills setting, recording to SD, to suspend over
the banch for when disassembling the next complicated mechanism, with no
exploded views in a manual

[Mark Zacharias]

"Michael Black" <et...@ncf.ca> wrote in message
news:alpine.LNX.2.02.1...@darkstar.example.org...

Really tells me nothing. I work in audio, but Kenwood also is a major player
in the amateur radio biz. SO, I would like to know more details. Type of
equipment, model number, problems / issues, whatever.

Maybe I can be of help, maybe not. I cannot know until I have:

MORE DETAILS.

mz

[gghe...@gmail.com]

Blast shield so when the caps let go they don't
spread goo onto the nearby circuit. :^)

(Maybe electrostatic shielding it looks to be on the caps right
after the rectifiers???)

George H.

George H.

[Geo]

On Fri, 6 Nov 2015 05:55:46 -0800 (PST), gghe...@gmail.com wrote:


>(Maybe electrostatic shielding it looks to be on the caps right
>after the rectifiers???)

My guess too.
Post-production development.
They have used an existing board fixing hole.
Possibly radiation into audio channel as one capacitor can will not be
at ground potential - although if the cap was doing its job...

Remove and listen for difference.

[Tom Miller]

<gghe...@gmail.com> wrote in message
news:c145e6f7-4793-466c...@googlegroups.com...

I there a fan for forced air cooling? If so, maybe it is for directing
cooling air?

Just another guess.

[jurb...@gmail.com]

Pretty sure that is a Kenwood KR-4070. The question was originally posed on Audiokarma by a guy who services and restores vintage audio.

He also noted that he worked on one with a later serial number and it had no such shield.

That's pretty much all we got.

[et...@whidbey.com]

That is a GREAT idea! I am now going to buy one. I do mostly
mechanical stuff and even though I try to document everything I take
apart I sometimes make a misteak. Thanks for posting your idea.
Eric

[N_Cook]

I've always been in the habit of felt-tip marking the joins of plates ,
ith a straight line across the join, before taking apart. And small
boxes for sub-sections that go together. But even then I sometimes end
up with unplaced parts.
This dash-cam is Nikkai ER-130V. Make sure whatever you get comes with a
viewer that allows selecting single frames

[et...@whidbey.com]

I would have though that viewing single frames would be standard.
Thanks for the heads up. Lots of the stuff I take apart has to be
cleaned and this removes marks. Right now I try to take pictures but
it can be a hassle. But just being able to hold an assembly in focus
and not have to stop and take a picture would be great.
Eric

[Cydrome Leader]

looks weird, like an afterthough.

Is there anything fastening the metal "shield" to the PCB below? Maybe
they had that board rattle apart of break loose with the large caps and
bridge rectifier attached to it. I'd almost expect the caps in something
of that age to be screwed down with a collar and have wire wrap terminals
or something weird like they did then.

There's quite a bit of stress on the parts in those big heavy receivers as
they get shipped across the world.

Heard from one guy that sent to the factory where they had audio gear
manufactured that the power transformers were all being screwed down
wrong, with the spring washer in the wrong place. He told the production
people that's not going to work, but they ignored that.

By the time the stuff made it to the US, every transformer busted free. It
all had to be reworked in the US. Whoops.

[Trevor Wilson]

**Looks suspiciously like a DIY'er addition to me. The only time I've
ever seen covers on caps are ones on old mains suppression caps.

--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Chuck]

No there wasn't. This receiver is from the late 70's and had a more
than adequate heat sink. Worked on quite a few of these back in the
day and I don't remember this piece of metal.

[Reinhard Zwirner]

jurb...@gmail.com schrieb:

> https://dl.dropboxusercontent.com/u/29948706/KR-4070%20Caps.jpg
>
> In a Kenwood receiver. It is steel, not aluminum.
>
> What is its purpose ?

Maybe just to fix the capacitors (instead of using glue)?

Not really convinced

Reinhard

[gregz]

I have used steel plates to help cut magnetic feed to sensitive circuits.
Steel changes the magnetic path. Can't say otherwise.

Greg

[Ron D.]

No real clue except an explosive shield.

There is a polarity on non-polarized caps. It is suggested that the "foil side" go to the low Z point in the circuit. Typically this would be important in a vacuum tube circuit. Not all caps are marked alike, "Foil side" used to be a common marking.

[Michael Black]

Wait. That sort of "polarity" had nothing to do with DC voltage, but
about which side went to ground. And it was because paper capacitors were
so large, and could be a source of noise pickup if the outer side wasn't
going to ground.

It never really came up because by the time of transistors, the paper
capacitors had mostly faded away.

Michael

[M Philbrook]

In article <alpine.LNX.2.02.1...@darkstar.example.org>,
et...@ncf.ca says...

or dried out :)

Jamie

[Ron D.]

Mr. Black:

yes.

But, these https://www.tedss.com/2020024048 0.1V 600V modern caps are BIG too.
There is a youtube video of a guy that made a device to help you sort out the foil side. The foil side to the Low Z point makes a lot of sense.

[Jeff Liebermann]

Notice the blue and black pair of wires that are carefully routed
around the shield. My guess(tm) is that they carry AC power from the
xformer partly obscured at the top of the photo. Also note that both
ends of the steel shield are at chassis ground through mounting
screws. The steel shield possibly provides some reduction in 60 Hz
(hummmmm) coupling to the power supply filter caps. Later revisions,
that didn't have the shield probably re-routed the AC wiring.


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[mako...@yahoo.com]

I'd agree with that.
Probably there was a hum or buzz in the low level magnetic phono circuits which are very sensitive.
Mark

[Jeff Liebermann]

Something must be wrong. Nobody ever agrees with me.

Marginally related anecdote: The easiest way to tell what something
does is to remove it and see what breaks. I used to own a 1970 Land
Rover Series IIa. In order to replace the spark plugs, I had to first
remove a steel "heat shield". This bothered me as I could see no
reason why a heat shield was necessary in such an open and drafty
engine compartment, with nothing nearby to protect. So, I removed it.
Everything was normal until I hit 57 mph, when the engine compartment
turned into a giant low pitched whistle, which made enough noise to
attract the attention of all the nearby drivers on the freeway.
Apparently the "heat shield" detuned the engine compartment so that it
would not whistle at operating speeds.

Remove the amplifier shield and see what happens. My bet is some low
level hum, that could only be measured on instruments, but which would
affect the advertised noise levels.

[gregz]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Sun, 8 Nov 2015 18:59:21 -0800 (PST), mako...@yahoo.com wrote:
>
>> I'd agree with that.
>> Probably there was a hum or buzz in the low level magnetic phono
>> circuits which are very sensitive.
>> Mark
>
> Something must be wrong. Nobody ever agrees with me.
>

I didn't even notice the wire.

Greg

[Cydrome Leader]

gregz <ze...@comcast.net> wrote:
> Jeff Liebermann <je...@cruzio.com> wrote:
>> On Sun, 8 Nov 2015 18:59:21 -0800 (PST), mako...@yahoo.com wrote:
>>
>>> I'd agree with that.
>>> Probably there was a hum or buzz in the low level magnetic phono
>>> circuits which are very sensitive.
>>> Mark
>>
>> Something must be wrong. Nobody ever agrees with me.
>>
>
> I didn't even notice the wire.

I didn't see it either. The shield looks OEM, even with the weird shape.
The plating looks intact and it has no handling marks as if it was rigged
up by somebody- no cut marks, no scratches from pliers etc.