MaccaAu
17-05-2019, 20:45
Dont want to bore with the long story, basically the amp had to recapped, and also ICs replaced due to slip of probe and a few bad caps.
She was working perfectly, this one day on fire up high pitch sound much worse on phono:eek:, with the decouping caps removed, no more issues. Either the OPA1642 was oscillating or a faulty part - lucky I was, a board come up and i have a new used board.
Installed LME49860 soic - dip adapter, electros on the phono are Pano FR and Nichicon PW( image 2 C123/124 47uf25v) near IC. Another thing, there isnt cross talk which was much worse before the new board:D, which is good
Kept the orignal phono cable this time inside the amp? was thinking of replacing it also ( can see the outer shield has a bit of oxidation, but maybe changing cable would introduce crosstalk:scratch:.
Currently decouping cap is a Wima FKP, was thinking of using a standard Auricap?
Changed resistors in signal path ( 2 of them yellow on image 2 R 144/143) to Vishay Dale RN65e
Wima cap? or Nichicon ES or Auricap? ( C118/117 red image 2)
Wonder if caps are best kept or removed filter ones C119/120 0.0047uf (gold cross image 2)
thanks Sam :)
image phonostage schematic
http://i64.tinypic.com/5d56jn.jpg
image 2 close up IC
http://i65.tinypic.com/2gwb382.jpg
She was working perfectly, this one day on fire up high pitch sound much worse on phono:eek:, with the decouping caps removed, no more issues. Either the OPA1642 was oscillating or a faulty part - lucky I was, a board come up and i have a new used board.
Installed LME49860 soic - dip adapter, electros on the phono are Pano FR and Nichicon PW( image 2 C123/124 47uf25v) near IC. Another thing, there isnt cross talk which was much worse before the new board:D, which is good
Kept the orignal phono cable this time inside the amp? was thinking of replacing it also ( can see the outer shield has a bit of oxidation, but maybe changing cable would introduce crosstalk:scratch:.
Currently decouping cap is a Wima FKP, was thinking of using a standard Auricap?
Changed resistors in signal path ( 2 of them yellow on image 2 R 144/143) to Vishay Dale RN65e
Wima cap? or Nichicon ES or Auricap? ( C118/117 red image 2)
Wonder if caps are best kept or removed filter ones C119/120 0.0047uf (gold cross image 2)
thanks Sam :)
image phonostage schematic
http://i64.tinypic.com/5d56jn.jpg
image 2 close up IC
http://i65.tinypic.com/2gwb382.jpg