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Old 27th January 2012, 07:14 PM   #1481
SY is offline SY  United States
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However I got deferred from the draft for another reason.
Not that there's anything wrong with that.
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Old 27th January 2012, 07:17 PM   #1482
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Tvr, I have a Dyna Mk4 tube amp that has a cap problem. It actually MOTORBOATS when I turn it on. I have a Marantz 10, (not 10B) with a cap leakage problem. OF COURSE, caps fail, but WHY change them when they still work OK? So what, a little extra ESR? You have mid-fi anyway, like having a Chevy and getting a valve job every 30,000 mi. Are you racing? If not, wait till the compression drops so much that the engine misses.
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Old 27th January 2012, 07:18 PM   #1483
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Did they defer you SY?
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Old 27th January 2012, 07:27 PM   #1484
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Nope.
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Old 27th January 2012, 07:32 PM   #1485
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Erno Borbely.
Thanks ...

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Originally Posted by john curl View Post
Tvr, sorry for your problem with increasing age, in my case, I have difficulty seeing well. However I got deferred from the draft for another reason.
Wanted to carry your scope ...


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Nope.
You carried your scope ...?
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Old 27th January 2012, 07:32 PM   #1486
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Nope.
I recieved the "Greetings" letter and sent back a request for appeal on the grounds that I had forgotten to renew my 2S, several months later I got a letter that the lottery had ended for that year so I got a permanent deferment.
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Old 27th January 2012, 07:46 PM   #1487
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THAT Corporation 300-series Low-Noise Matched Transistor Array ICs
Of interest?
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Old 27th January 2012, 08:51 PM   #1488
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I have not posted a picture in so long, I have no clue what site I used to link to. Any advice? I have the cleaned up DH 120 drawing.
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Old 27th January 2012, 09:13 PM   #1489
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Anatech, Point well made that vintage equipment is likely far from its original performance. I did replace the electrolytics as they have practical life expectancy of 7 to 10 years. As a side benefit, the newer parts have lower ESR.
7 to 10 years is very pessimistic for good quality electrolytics... try 20 years or more.

My current AV receiver is coming up on 19 years old (I only use it as a stereo amp) and although its had a couple of minor repairs including two small signal driver transistors in one of the main output channels none of the caps have been replaced or needed to be replaced.

For many years I had an early 70's Sony amp as a spare amp (a TA-1150) and again, it had a couple of repairs over the years including new output transistors after being subjected to shorted outputs before it was given to me, but as far as I know or could see none of the caps had ever been replaced, nor needed to be, and apart from a slightly scratchy volume control it was still working perfectly when I gave it away a couple of years ago, by which time it was close to 40 years old...

As far as I can see electrolytics made in the last 30-40 years are a lot more reliable than we give them credit for, they generally either fail from excessive heat, or lack of use. As long as the design doesn't place them in a location that gets hot and the equipment gets occasional regular use so the oxide coating is maintained they can last a long time indeed.

Leave the equipment turned off for 10 years and you might have a problem, yes.
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Last edited by DBMandrake; 27th January 2012 at 09:18 PM.
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Old 27th January 2012, 09:52 PM   #1490
tvrgeek is offline tvrgeek  United States
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5 to 8 is manufactures spec. Feel free to verify, I did. We had a lot of trouble when I was in industry as we did have that hot warehouse. I was in the failure analysis lab at the time and had to look into this problem. Performance mattered and we measured, as opposed to "sounds OK to me". People are touchier when they pay hundreds of thousands for equipment. Anyway, as I said, I change at about 20. The point originally being made is vintage equipment is not only older design and older component design, but some may not be up to original spec for other reasons. Aluminum electrolitics are one of those. Pots, connectors, switches, relays, and the bad habit or wire wrap posts are others. But then again, there is no such thing as a GOOD pot, connector, relay...... Any adjustment may not be correct, like bias or symmetry.
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