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Sugden P28
Sugden P28
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Old 26th February 2013, 06:40 PM   #151
egelundvej25 is offline egelundvej25  Denmark
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Join Date: Jan 2008
Location: Esbjerg, Denmark
No Sorry Michel - I have ordered both power transistors (2SB776 & 2SD896) and drivers (BC639 & BC640) - since I can read that they (the drivers) offen is making trouble. The insulators looks like they are transparent but I will double check when power transistors are changed.

Regards, Michael
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Old 22nd March 2013, 02:45 PM   #152
makalu is offline makalu  France
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Join Date: Feb 2013
Location: Pont de Beauvoisin
Hello Michel ( Michael?).
I have also a Sugden A28 ( not A28II) . Is it possible to send me a schematic of this amplifier ? . I have to repair it , and whithout schem... How to say ...
It would be fantastic .
Thanks . MAKALU
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Old 29th March 2013, 10:57 AM   #153
makalu is offline makalu  France
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Quote:
Originally Posted by makalu View Post
Hello Michel ( Michael?).
I have also a Sugden A28 ( not A28II) . Is it possible to send me a schematic of this amplifier ? . I have to repair it , and whithout schem... How to say ...
It would be fantastic .
Thanks . MAKALU
My adress : chamechaude@voila.fr
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Old 30th March 2013, 03:53 PM   #154
korben69 is offline korben69  France
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Join Date: Nov 2006
Location: Lyon
Hi makalu

YGM as requested
Last time I've heard about makalu it was a long time ago...
I was wearing some free clothes furnished by French Army.
As far as I remember, it makes me wonder about gloves...
Regards

Phil

PS : I'm gathering new caps for my A28
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Old 3rd April 2013, 03:54 PM   #155
makalu is offline makalu  France
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Join Date: Feb 2013
Location: Pont de Beauvoisin
Hello .
As Marc 22 ( post Nr 113) , my A28 is broken . Zener diode( near R620 Ohm , wirewound ) is in short circuit , and the value is unreadable. Is anybody able to help me please ? And I would like to get a schematic of A28( not A28II ) with locations , if they exist ...
Thanks
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Old 3rd April 2013, 04:33 PM   #156
korben69 is offline korben69  France
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Hi makalu

ZD1 seems to be 30 or 33V/1W.

Phil
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Old 3rd April 2013, 05:23 PM   #157
Michel is offline Michel  Canada
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Join Date: Nov 2004
Location: L'Assomption, QC
Hello Makalu,

Have you received the Sugden A28 documents I sent you?

Michel
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Old 4th April 2013, 08:04 AM   #158
makalu is offline makalu  France
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Join Date: Feb 2013
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Hello Michel . I well received the documents . Thanks . It's wonderful
Dom.
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Old 4th April 2013, 08:07 AM   #159
makalu is offline makalu  France
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And thanks also to my neighbour KORBEN69 . The zener diode is realy a 30v (or 33v ?) one .
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Old 16th April 2013, 11:28 AM   #160
makalu is offline makalu  France
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Join Date: Feb 2013
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Hello ! In the original A 28 , Operating voltage after rectification and filtering is given to 57 V in the diagram. It doesn't correspond to my circuit measures. I have 78v. Some talk on the forum from 71 to 73 v. It must depend on the transformer of power supply, I guess. ..anyway I will control.the 4700μf caps . They look good in capacitance, but in operation, according to ESR and aging ,it's less certain. Result, tensions in the circuit are rather different from those of the diagram alone, mostly around two potentiometers for setting final stages. Is a Forumer could send me some measurements of voltages around the transistors of the driver stage (Q9, Q17 and BC639 top of the diagram which 47.7 v on the collector) and the initial 73v too. Similarly the power transistors? Thanks

Makalu
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