No voltage on pins 8-19 on SX-1050 awr 103 board????!!!!

While I'm sure Mark and Steve deserve a monumental thumbs up for this project, I think Cheryl is the hero in this story. "Behind every great AK'ers is a great woman.":thmbsp::music::music::music:
 
I have 733's but no 992's, Iwill swap out transistors this evening.

one pair at a time, just swap for now, no substitutions.

And I changed my mind, do the Q7 / Q8 swap first.

Just for reference:
The 2sa725 is BCE layout
The ksa733 is EBC layout
The ksa992 is ECB layout and is low noise.
 
Haven't had time to swap transistors, however I went back and checked effect of controls on static. with no speakers connected, (headphones only) all inputs deselected, I tested effects of control switches. The tone controls DO have an effect, Bass and treble do alter the overall tone but not the Volume of static. 30Hz and 8kHz filters seem to have no affect.(with tone switch to on)
 
Does the volume of the static go up and down with the volume control? Does moving the balance to the left elminate static on the right (and vice-versa)?
 
No balance and volume controls have no affect. volume at min.= static on right channel, balance left= static on right channel. stereo mono set to mono= static on right channel.with music source if volume is increased volume of music will overcome static. static sometimes is louder sometimes softer.
 
Bypass the tone controls (tone = off). Static?

Edit: You MUST ensure all switches are clean. Take the red DeOxit tube, and with the front panel off, slip the tube between the spring and the shaft of the pushbutton switches near the bottom right or left of the shaft...there's a small opening there where you can shoot a liberal amount of cleaner into the switch (don't worry about making a mess, but a plastic cover or newspapers on your table are a good idea). Do this on each switch (all of them), work the switches about 50 times each, then go back through them once more.

The toggle switches must also be clean, but these aren't as easy.
 
E.W. thanks for the advice, I will have to buy some more DeOxit, as I seem to have used all I had or loaned it to my son for his projects.should have known better (he never returns anything) I tried cleaning them once a while back, and thought that I had suceeded, I'll have to try again.
 
Ok, standard questions re: static...

has it been thoroughly deoxited? all switches?

Both channels? NO? just one...
phono 1/phono2/aux affect it? no?
Stereo/mono affect it? no?
muting (-20db no effect?) ??no??
loudness no effect? ??no??
balance control affect it? no?
Volume control affect it? no?
tone on /off affect it? (off is a total bypass of the tone amp) no?
30hz filter in/out affect it ? no?
8khz filter in/out affect it? no?
BOTH 30hz and 8khz OUT affect it? (that's a total bypass of the filter amp) no?

looks like flat amp between the volume control and the output. After that the tone bypass and filter bypass eliminate all other active devices (but not the bypass switches).

Quick test is to swap Q5 & Q6 (2sk30aw)(repl:ksk30yta) and see if it moves
and then Q7 and Q8 (2sa725) (do you have any ksa733's or (ln)ksa992's?)
and see if it moves...

flat amp is behind the front panel and has volume control and a lot other panel stuff on it.

I guess I could have stressed it more, that the signal is going through several switches (which can generate that type of noise), and the signal goes through those switches even when it does NOT go through any more transistor circuits and instead uses the bypass paths.

plus instead of saying "affect" I should have said "eliminate". The tone controls and filters when operating will affect the tonal balance of the noise, but we were looking for where the noise STARTS.
 
Mark I swapped Q7 and Q8 Static disappeared. is it possable it may have been a cold solder joint on Q8? I went back and checked DC Balance and Idle Current readings, all are fine. I will leave her running for a while and see what happens. Fingers,Toes and Eyes are crossed.
 
Mark I swapped Q7 and Q8 Static disappeared. is it possable it may have been a cold solder joint on Q8? I went back and checked DC Balance and Idle Current readings, all are fine. I will leave her running for a while and see what happens. Fingers,Toes and Eyes are crossed.

Mine too

The heat from soldering could have affected the transistor. Give it time.
 
Been on all night, so far so good,leaving it on all day,
Oh and by the way, Have a Happy Thanksgiving, To one and all at AK. I'm off to my sons house to enjoy the Grand Kids. Later.
 
I'm going to go back and check all voltages later and make any adjustments needed. That light at the end of this very long tunnel seems to be getting brighter.
 
Careful checking those voltages one last time. I slipped once and had to start all over again :sigh:


If you check the thread, he learned that lesson already. On the bright side, he now has 8 new On-semi mj21193/94 outputs for really robust output stages.
 
Lesson was learned very well! everything is looking real good, I'm beginning to think we may be at the end. I think I see daylight, if she remains stable, she will take her rightful place as the crown jewel of my audio system. Ijust listened to over 3 hours of the sweetest music I have heard in a long time. she is looking complete.
 
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