There is a diode on the rear trace side of board I don’t think it’s in the schematic it was there from factory a 10d1 it goes to positive end of the 100uf cap to the resistor 15k maybe I should remove it? I replaced it with a 1n5393
Sansui BA-2000 bias adjustment
- Thread starter quadmatrix82
- Start date
C617 has 7v to it and c618 has -1v to it connecting positive probe to positive leg and negative speaker terminal for the black probe
Tr6 612 emitter voltage -6.2v looks this one is an issue too
Tr604 e -67.2v c -18.2v b-67.2v
Tr604 e -67.2v c -18.2v b-67.2v
Tr608
C -68.2v
B -6.2v
E -5.6v
C -68.2v
B -6.2v
E -5.6v
Yes get rid of it - it seems from your description of where it is connected that this is exactly the problem.I am hopeful that removing this will resolve the issue.
BTW
TR616 is about as close to the issue as you can get - namely only 580mV across the 13V zener it is connected to - that's why I asked you to remove and test it in post #38.
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I am hopeful that removing this will resolve the issue.
BTW
TR616 is about as close to the issue as you can get - namely only 580mV across the 13V zener it is connected to - that's why I asked you to remove and test it in post #38.
We have music!!
I removed the diode on the rear trace here is a photo of the original one i wonder why it was fitted? It looks factory to me I wonder how this thing worked all these years…
You may recall d616 was removed from its location also a 10d1…maybe the factory or someone moved this diode to this location for some strange reason? Putting a new one in the correct location and leaving the trace side diode in place maybe caused more issues I didn’t experience previously…either way the trace side diode shouldn’t be there as Hyperion noted.
We now have +67v on pin 26 and -67v on pin 27 distortion is gone and Fleetwood mac is sounding great even on my test speakers
I’ll play it for a few hours and dial the bias back in before reassembling but it’s sounding promising.
Thankyou Hyperion for your patience and guidance, so grateful for this community and expertise. I learn something new from every project!
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Wow! - I knew I was on the right track, (pun not intended) but that added diode! - Jumpin Jehosephat!!! - that's enough to try the patience of a saint.
Perhaps needless to say, if I knew it was there I would have been questioning that diode a long time ago.
Anyway, I am glad it seems to be working much better now, I'll leave you in peace to get it readjusted and sounding great.
Perhaps needless to say, if I knew it was there I would have been questioning that diode a long time ago.
Anyway, I am glad it seems to be working much better now, I'll leave you in peace to get it readjusted and sounding great.
This one was certainly testing my patience too! I don’t know why I didn’t think of it earlier out of sight out of mind perhaps, also the manual has a lot of errors and board errors (colour codes don’t line up with the cables) so i thought it was another service manual error given how original it looked in place. It’s worked flawlessly all day and sounding better than ever so once again thankyou
