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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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https://dl.dropboxusercontent.com/u/...070%20Caps.jpg
In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? |
#3
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"M Philbrook" wrote in message
... In article , says... https://dl.dropboxusercontent.com/u/...070%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 What was the original question? Mark Z. |
#4
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On Thu, 5 Nov 2015, Mark Zacharias wrote:
"M Philbrook" wrote in message ... In article , says... https://dl.dropboxusercontent.com/u/...070%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 What was the original question? "Capacitor shield?" At least, that was in the subject header. Michael |
#6
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On 06/11/2015 01:48, wrote:
https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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 |
#7
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"Michael Black" wrote in message
news:alpine.LNX.2.02.1511052201300.16969@darkstar. example.org... On Thu, 5 Nov 2015, Mark Zacharias wrote: "M Philbrook" wrote in message ... In article , says... https://dl.dropboxusercontent.com/u/...070%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 What was the original question? "Capacitor shield?" At least, that was in the subject header. Michael 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 |
#8
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On Thursday, November 5, 2015 at 8:48:39 PM UTC-5, wrote:
https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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. |
#9
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On Fri, 6 Nov 2015 05:55:46 -0800 (PST), 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. |
#10
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![]() wrote in message ... On Thursday, November 5, 2015 at 8:48:39 PM UTC-5, wrote: https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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. I there a fan for forced air cooling? If so, maybe it is for directing cooling air? Just another guess. |
#11
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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. |
#12
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On Fri, 06 Nov 2015 08:40:34 +0000, N_Cook wrote:
On 06/11/2015 01:48, wrote: https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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 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 |
#13
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On 06/11/2015 17:21, wrote:
On Fri, 06 Nov 2015 08:40:34 +0000, N_Cook wrote: On 06/11/2015 01:48, wrote: https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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 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 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 |
#14
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On Fri, 06 Nov 2015 17:52:19 +0000, N_Cook wrote:
On 06/11/2015 17:21, wrote: On Fri, 06 Nov 2015 08:40:34 +0000, N_Cook wrote: On 06/11/2015 01:48, wrote: https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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 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 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 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 |
#15
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wrote:
https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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. |
#16
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On 6/11/2015 12:48 PM, wrote:
https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? **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 |
#17
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On Fri, 6 Nov 2015 10:43:40 -0500, "Tom Miller"
wrote: wrote in message ... On Thursday, November 5, 2015 at 8:48:39 PM UTC-5, wrote: https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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. I there a fan for forced air cooling? If so, maybe it is for directing cooling air? Just another guess. 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. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
#18
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#19
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wrote:
https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? I have used steel plates to help cut magnetic feed to sensitive circuits. Steel changes the magnetic path. Can't say otherwise. Greg |
#20
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![]() 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. |
#21
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On Sun, 8 Nov 2015, Ron D. wrote:
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. 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 |
#22
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#23
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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. |
#24
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On Thu, 5 Nov 2015 17:48:33 -0800 (PST), wrote:
https://dl.dropboxusercontent.com/u/...070%20Caps.jpg In a Kenwood receiver. It is steel, not aluminum. What is its purpose ? 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 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#25
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I'd agree with that.
Probably there was a hum or buzz in the low level magnetic phono circuits which are very sensitive. Mark |
#26
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On Sun, 8 Nov 2015 18:59:21 -0800 (PST), 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. 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. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#27
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Jeff Liebermann wrote:
On Sun, 8 Nov 2015 18:59:21 -0800 (PST), 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 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. |
#28
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gregz wrote:
Jeff Liebermann wrote: On Sun, 8 Nov 2015 18:59:21 -0800 (PST), 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. Greg 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. |
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