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AU9900 refurb question.....

slimecity

slimecity

Super Member
Hi - I have bought an AU9900 that has been totally reworked except (somewhat strangely) with respect to the fusing resistors and the VD1212 diodes. I intend pulling and replacing all of these before they cause issues. Quick question - there are some 1/4W fusing resistors - I'll replace those with 1/4W metal film types. What about the 1/2W fusing resistors - logically replace these with 1/2W metal film type equivalents? What do people think? cheers!
 
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slimecity said:
Hi - I have bought an AU9900 that has been totally reworked except (somewhat strangely) with respect to the fusing resistors and the VD1212 diodes. I intend pulling and replacing all of these before they cause issues. Quick question - there are some 1/4W fusing resistors - I'll replace those with 1/4W metal film types. What about the 1/2W fusing resistors - logically replace these with 1/2W metal film type equivalents? What do people think? cheers!
Click to expand...


In a word, yes ;)
 
Cheers thanks guys. Next question - the guy who part-refurbed this amp replaced some driver transistors but not others on the driver board (F2661). Im just curious about this. Ie: he's replaced TR's 19-22 (2SC1628, 2SC1811, 2SA818, 2SA896) with Onsemi types, however the original pre-drivers TR23-26 remain in place - I take it its OK to leave these, as they are (a) reliable (if still functioning), and (b) suitable replacements dont really exist for them? They are 2SD382 & 2SB537. He's done quite a good job actually, apart from as per my comments above.....thanks!
 
2SC1628 and 2SA818 are 'Uniwatt' transistors that are known to exhibit problems with age - like very low gain. 2SD382 and 2SB527s are not in this category, so shouldn't need to be replaced.

You really should read the threads on here about AU-9900 and AU-11000 reconditioning - and a lot of your questions will be answered. :yes:

http://audiokarma.org/forums/showthread.php?t=229708&highlight=AU-9900

http://www.audiokarma.org/forums/showthread.php?t=223020&page=2

http://audiokarma.org/forums/showthread.php?t=228092&highlight=AU-9900

http://audiokarma.org/forums/showthread.php?t=398717&highlight=AU-9900

http://audiokarma.org/forums/showthread.php?t=230851&highlight=AU11000
 
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