Hello, (Excuse my english because I'm fench)
I'm an happy possessor of an excellent cambridge audio A3i since 1999.
I repair it sometimes and would share my experience (to Alex and all).
April 2001 :
- temperature drift problems -> change green leds and Q8/Q10 and R16/R18 with 3,3k 1/2 W (done by my dealer in France Patrick Chochoy from Michael Creek) and bias 18 mV between
Emiters of Q13/Q14 (recommandations)
- Error manipulation -> Short Circuit --> change 4A Fuse and Q11, Q12, Q9
May 2005 :
- Fuses 4A broken --> change fuses and bias
July 2005 :
- No sound on left channel -> clean contact relay and repair board circuit
February 2006 :
- after a while LED 1 extinguished and Q13 heats and fuse 4A brokes --> LED 1 HS -> change the four leds (identicals : VF = 2,10V @ 12,5mA)
October 2006 :
- LED1 weak -> Q10 HS ( Beta = 40) -> change Q101 (Beta = 126)
December 2006 :
- Q8 HS --> change (BC640)
- little dissipator on Q8/Q10 to prevent overheating problems
Today (July 2009) :
I think had a little fan in the amp
Questions :
how really adjust the bias (amp open ? amp closed ? how many time,...) ?
may i have the schematic ?
Thank's
I'm an happy possessor of an excellent cambridge audio A3i since 1999.
I repair it sometimes and would share my experience (to Alex and all).
April 2001 :
- temperature drift problems -> change green leds and Q8/Q10 and R16/R18 with 3,3k 1/2 W (done by my dealer in France Patrick Chochoy from Michael Creek) and bias 18 mV between
Emiters of Q13/Q14 (recommandations)
- Error manipulation -> Short Circuit --> change 4A Fuse and Q11, Q12, Q9
May 2005 :
- Fuses 4A broken --> change fuses and bias
July 2005 :
- No sound on left channel -> clean contact relay and repair board circuit
February 2006 :
- after a while LED 1 extinguished and Q13 heats and fuse 4A brokes --> LED 1 HS -> change the four leds (identicals : VF = 2,10V @ 12,5mA)
October 2006 :
- LED1 weak -> Q10 HS ( Beta = 40) -> change Q101 (Beta = 126)
December 2006 :
- Q8 HS --> change (BC640)
- little dissipator on Q8/Q10 to prevent overheating problems
Today (July 2009) :
I think had a little fan in the amp
Questions :
how really adjust the bias (amp open ? amp closed ? how many time,...) ?
may i have the schematic ?
Thank's