nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239 
|
Post by nashou on Nov 13, 2016 21:16:31 GMT -5
I know it looks wrong but that's what I am getting unless the 9.8 k resistor I am measuring off of is not the right one. But it has to be.
The board layout diagrams suck. I have an original manual on its way. Hopefully I can then know exactly what part is what.
No resistor numbers on PCB.
|
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 13, 2016 21:21:47 GMT -5
Get me voltages on both sides of R116 and R118. One side of R116 is 4.10 the other is in the mV's one side of R 118 is -9.20 the other I -21.85 |
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 13, 2016 21:38:02 GMT -5
Here is a pic of the bottom of the PCB R117 notation is between the North and south of resistor. understand?   |
|
|
|
Post by mastertech on Nov 13, 2016 22:14:33 GMT -5
At this point your pictures do not match the schematic and I see what you mean about the board layout pics. So it is probably best to wait until you get that manual. Let me know if you need help.
|
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 13, 2016 22:25:24 GMT -5
At this point your pictures do not match the schematic and I see what you mean about the board layout pics. So it is probably best to wait until you get that manual. Let me know if you need help. It seemed strange to me as well. There have been known PCB's marked wrong and/or schematics wrong in the yamaha line. Might be one of them here ! ugh Hopefully The original service manual will clear up some things. but when I look at the other channel, its laid a bit different but they match up and corraborate the bad channel .  Nashou |
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 14, 2016 17:52:30 GMT -5
|
|
|
|
Post by mastertech on Nov 14, 2016 19:01:59 GMT -5
That is much better. Did you want to continue on your own now or still want assistance?
|
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 14, 2016 19:06:27 GMT -5
Ok Mac figured it out!!!! The Schematic is wrong. They have R117,R118 and D109 and D110 swapped . The Resistors should connect to Film Capacitors C107 and c108 for their respective channels. So R117 should be where D109 is and D109 should move to where R117 is.  Right? EDIT, still need help Athanasios |
|
|
|
Post by mastertech on Nov 14, 2016 19:11:58 GMT -5
Yes, I saw that. Good job.  Ok, back to where we left off. Get me voltages on both side of R115 and R116. |
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 14, 2016 19:25:32 GMT -5
Yes, I saw that. Good job. Ok, back to where we left off. Get me voltages on both side of R115 and R116. R115 -11.09 and -4.9 R116 +4.04 and +189.3 mV the +/- 4 voltages are on the transistor side of TR103,104 |
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 14, 2016 19:43:49 GMT -5
Ok I was looking at the schematic to see why i am getting voltage on the Gates of that side of TR107. SO I looked at what could have shorted or be acting strange from that gate. going straight
from the gate along the straight line you come eventually to C123. I measured voltages on either side where as on C124 i get mV. It was -21 on one side and -4.5 on the other.
I forgot what voltage was on the Negative side of the cap let me go check again.
-21 is on positive side of cap.
|
|
|
|
Post by mastertech on Nov 14, 2016 19:50:03 GMT -5
I would prefer not to jump around just yet.
I assume TR107,TR103,TR105 are still removed.
Remove TR108,TR104,TR106 and retest voltages on R116.
|
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 14, 2016 19:57:55 GMT -5
-6.96 and -13.7 forget the previous numbers I forgot to plug amp back in !!!
-6.96 goes to TR104
|
|
nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239
|
Post by nashou on Nov 14, 2016 20:02:34 GMT -5
And now I am getting voltages on C124 just for reference .
|
|
|
|
Post by mastertech on Nov 14, 2016 20:06:26 GMT -5
-6.96 and -13.7 forget the previous numbers I forgot to plug amp back in !!! -6.96 goes to TR104 This is with TR108,TR104,TR106 removed? |
|
