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12th January 2012, 08:56 AM
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#1 |
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diy newbie
diyAudio Member
Join Date: Sep 2011
Location: norway
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cayin 270p
Just wanted to share this schema..... I have to of this amps, bought them new for about 15 years ago, and now they produse a low sound in mid and high when idling... caps changing perhaps? any toughts?
they also been to the seller for a upgrade abouth 7-8 years ago... where there was added some transistors and what not... dont know if that really helpt. will post pics on that later. anyone ever owned these amps.. thought on quality?? they served me well, so no regrets, but want to adress the zzzzzzumming when idling. zumming on both amps= same problem? also want to know what the different trimpots r... ie bias, dc and so on thanks for any input Regards
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" If you're going throu hell, keep going" Last edited by oiphy; 12th January 2012 at 08:58 AM. |
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25th January 2012, 03:07 PM
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#3 |
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diyAudio Member
Join Date: May 2006
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The design seems reasonable, I never heard of this manufacturer.
Caps would be the right place to start, the main power supply ones and then the ones following voltage regulators. Id try put a small value cap of say 47uF accross DW107 zener. |
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25th January 2012, 06:26 PM
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#4 |
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diy newbie
diyAudio Member
Join Date: Sep 2011
Location: norway
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homemodder. producer is cayin sparks.... they do alot of hifi. low cost from china but supprisingly good stuff. .was thinking about the caps. you know what the different trimpots adjust?
regarding zenercap what will be the purpose? thanks
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" If you're going throu hell, keep going" |
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25th January 2012, 07:59 PM
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#5 |
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diyAudio Member
Join Date: Apr 2004
Location: Norwich, UK
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R106 adjusts DC offset. VR101 adjusts the current in the VAS stage. VR102 adjusts the idle bias current.
A capacitor across DW107 would filter any noise the Zener produces. I would say your issues are caused by capacitors near the end of their life. |
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20th April 2012, 06:15 PM
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#7 |
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diy newbie
diyAudio Member
Join Date: Sep 2011
Location: norway
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recapping
so started the job of recapping when i found this little rascal...
 63v on a 75v rail...... think that was a problem  anyhow... now changing to kendeils all over psu.
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" If you're going throu hell, keep going" |
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20th April 2012, 07:46 PM
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#10 |
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diyAudio Member
Join Date: Jan 2005
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The schematic, it has one Vbe multipler between the bases of the driver transistors with the pot for bias adjust, then another fixed Vbe multipler between the bases of the output transistors, something i've never seen before.
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