I have not found a BOM for an SX5 here yet so I have done my own poking...
Subject machine: SX5, fully intact, works 'cept for real bad distortion on the right.
For S&G's I cleaned up the pots and did the suggested idle current set. Left, I was able to dial in to 23.5mv, but I set it lower to 21mv - this uses a steel heatsink rather than AL and is packed tight so I wanna err on the side of cool.
Right side, could not set idle to save anyones life, yet I have sound so peeking at the SM I conclude that the Q326 (2SB686) side of the dual emitter resistor aint got nothing on it.
I have my +/- rails of +37.8ish and -38. The schematic says +/- 35, the PCB board diagram says +33.5/-33.5
Thinking, uh oh, aint I a little high I look at the schematic for the rails and see:
Which tells me as usual, the rails are directly off the rectifying diodes so WYSIWYG. I have to assume this is ok right?
I have not checked the outputs of Q403/Q404 for the +/- voltages of the other stuff just yet...
Anyways...thinking Q326 has failed open I check 322 just before it and instead of the desired -1.2v I find -13.3v.
pic from manual that I used to test:
Using the left side as a template, yeah, that side is ok.
However, using speakers, the left side is not distorted, but it sounds tinnish to the point of perhaps a hi-freq scratch? Diff inputs?
I am off the mind to do both sides from the 2SA798s on in.
I have exactly 4 virginal 2SA798s from many many years ago. I will use them unless someone says "no, you must use KSA992s matched and flipped...
So amp only, and figuring a recap (and yes, all the resistors with triangles of death are still intact and functioning I can replace nontheless if ordered to do so)
I get:
Outputs:
Q325,326 = 2SB686, replace with either 2SB817 or 2STA1694 or ?
Q327,328 = 2SD716, replace with either 2SD1047 or 2STC4467 or ?
Digikey has both the STA/STC pair are half the price
Q321-324 sets of 2SA850/2SC1735 with 512-KSA1220AYS/512-KSC2690AYS
Q315-318 2SC2603 replace with KSC945C or KSC1815 (got a bunch of them)
Q307,308 2SC1845 replace with KSC1845
Q309,310 2SC2362 replace with KSC1845
Q313,314 JC501 replace with 2SC945A?? (this was a recommended onkyo fix from somewhere)
Q311,312,319,320 2SA1115 replace with???? Im drawing a blank here.....
And if I want to replace D306-309 (WZ046 - 4.6v zener) is there a preferred part?
and the plethora of 1S1555's...I know everyone uses 1N4148s, but I got a bajilion 1N914s which some say are 'electrically equivalent' - ok to use?
Any insights on the missing parts and comments on my selections thus far?
thanks guys...
edited to remove double pics and correct some tranny number typos
Subject machine: SX5, fully intact, works 'cept for real bad distortion on the right.
For S&G's I cleaned up the pots and did the suggested idle current set. Left, I was able to dial in to 23.5mv, but I set it lower to 21mv - this uses a steel heatsink rather than AL and is packed tight so I wanna err on the side of cool.
Right side, could not set idle to save anyones life, yet I have sound so peeking at the SM I conclude that the Q326 (2SB686) side of the dual emitter resistor aint got nothing on it.
I have my +/- rails of +37.8ish and -38. The schematic says +/- 35, the PCB board diagram says +33.5/-33.5
Thinking, uh oh, aint I a little high I look at the schematic for the rails and see:
Which tells me as usual, the rails are directly off the rectifying diodes so WYSIWYG. I have to assume this is ok right?
I have not checked the outputs of Q403/Q404 for the +/- voltages of the other stuff just yet...
Anyways...thinking Q326 has failed open I check 322 just before it and instead of the desired -1.2v I find -13.3v.
pic from manual that I used to test:
Using the left side as a template, yeah, that side is ok.
However, using speakers, the left side is not distorted, but it sounds tinnish to the point of perhaps a hi-freq scratch? Diff inputs?
I am off the mind to do both sides from the 2SA798s on in.
I have exactly 4 virginal 2SA798s from many many years ago. I will use them unless someone says "no, you must use KSA992s matched and flipped...
So amp only, and figuring a recap (and yes, all the resistors with triangles of death are still intact and functioning I can replace nontheless if ordered to do so)
I get:
Outputs:
Q325,326 = 2SB686, replace with either 2SB817 or 2STA1694 or ?
Q327,328 = 2SD716, replace with either 2SD1047 or 2STC4467 or ?
Digikey has both the STA/STC pair are half the price
Q321-324 sets of 2SA850/2SC1735 with 512-KSA1220AYS/512-KSC2690AYS
Q315-318 2SC2603 replace with KSC945C or KSC1815 (got a bunch of them)
Q307,308 2SC1845 replace with KSC1845
Q309,310 2SC2362 replace with KSC1845
Q313,314 JC501 replace with 2SC945A?? (this was a recommended onkyo fix from somewhere)
Q311,312,319,320 2SA1115 replace with???? Im drawing a blank here.....
And if I want to replace D306-309 (WZ046 - 4.6v zener) is there a preferred part?
and the plethora of 1S1555's...I know everyone uses 1N4148s, but I got a bajilion 1N914s which some say are 'electrically equivalent' - ok to use?
Any insights on the missing parts and comments on my selections thus far?
thanks guys...
edited to remove double pics and correct some tranny number typos
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