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Post by mastertech on Mar 13, 2014 20:58:22 GMT -5
My board is from an SC1522 Elite. Has a hair line crack through a dozen or 2 traces, top and bottom. Could not even see it until I used my loupe. DMM on continuity found it though. Receiver turned on fine, had video but no sound out of anything and did not go into protect.
Class D amp. All voltages were good until I checked for +/-7v for the preamp section. Traced back to audio input board and had 7v in but not out to preamp. Used DMM on continuity to follow traces from input across board going from top to bottom a dozen times until I hit a spot with no beep. Then looked at board with loupe and saw the mess. Put it off to the side until Sat.. Off to jersey tomorrow.
I will look at schematics for yours as soon as I have a chance.
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Post by mastertech on Mar 13, 2014 21:10:53 GMT -5
Schematics for the A700 could be the same. Has the correct outputs. We can get back to this tomorrow maybe. I don't know what time I will be back though.
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nashou
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Post by nashou on Mar 13, 2014 21:13:07 GMT -5
sounds good. JBmeyer from the other site lives in Jersey what part are you going to?
Nashou
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Post by mastertech on Mar 13, 2014 21:20:52 GMT -5
Northern part. Only 1 1/2 hrs. from me. I bought a couple street rods and going to pick 1 up tomorrow.
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nashou
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Post by nashou on Mar 13, 2014 21:30:37 GMT -5
Northern part. Only 1 1/2 hrs. from me. I bought a couple street rods and going to pick 1 up tomorrow. Sweet !! We will want pics !!! Nashou |
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nashou
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Post by nashou on Feb 15, 2017 21:43:25 GMT -5
Ok Lets get back to this. I got the amp to go on by disabling the Protect circuit by pressing the Info and Tone Control and holding down the two buttons for 3 seconds and you can hear the
speaker relays click on. I checked the voltages on all outputs and got on all output devices:
E= mV range
C= 60 vdc
B= .5 volts
Now these are either + or - depending on device
They are 2SA1695's and 2SC4468's .
The display does not work it will flash sometimes at onset of power on then go dark.
Not sure where to go from here.
What else would cause the protect to go on if the amp is not the issue.
Diode testing those output devices showing them all ok.
nashou
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Post by mastertech on Feb 16, 2017 11:12:14 GMT -5
Did you try the procedure shown on page 27 on the SM for starting self diagnostic mode which includes pressing and holding the "main zone" button along with the "info" and "tone control" buttons. The display should be on in this mode.
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nashou
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Post by nashou on Feb 16, 2017 13:47:54 GMT -5
Did you try the procedure shown on page 27 on the SM for starting self diagnostic mode which includes pressing and holding the "main zone" button along with the "info" and "tone control" buttons. The display should be on in this mode. I'll try when I get home. But I wonder if it will go through with it since the protect mode kicks in. Maybe if I hold those three down as in how its done for overriding the protect mode it will allow it to stay on? Guess I'll have to give it a shot if it doesn't work the service Manual way. EDIT: Now that I am home and have the manual infront of me that is exactly what i did to get the amp to turn on so I could get the readings off the output amps. The display does not turn on. One thing I should mention is the ribbon cable and connector, that go to the display, both had some corrosion on them. I cleaned them up and think they are ok now. But maybe that had or has something to do with it? Nashou |
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Post by mastertech on Feb 16, 2017 18:11:03 GMT -5
Are you able to do voltage testing on the CPU pins (ic908) with the unit fully assembled and powered up?
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nashou
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Post by nashou on Feb 16, 2017 18:47:00 GMT -5
Are you able to do voltage testing on the CPU pins (ic908) with the unit fully assembled and powered up? I should be able to on the top board. But while probing around with it out of protect mode I found A cap that had voltage on both sides C4209. That led me to look at the IPVE line that should be 0 volts I believe and I am getting voltage at all points for that line. About 2.xx volts. But what should I look at at IC908 or should we investigate that IPVE line? Nashou |
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nashou
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Post by nashou on Feb 16, 2017 19:27:31 GMT -5
Ok Looks like I have some wrong voltages on ic908 around the pins for the DOCK_N_DET and others near it.
Ill go right to left
pin 36 ok
pin 35 1.324
pin 34 3.3
pin 33 1.324
pin 32 1.35
pin 31 1.356
pin 30 ok
pin 29 1.34
pin 28 ok
pin 27 ok
So whats next? Or do you have other ideas?
Nashou
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Post by mastertech on Feb 16, 2017 20:15:49 GMT -5
test voltage at pins 4,125,126,127,134,135
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nashou
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Post by nashou on Feb 16, 2017 20:45:30 GMT -5
All are good except 135 was .5 volts and i test 136 as well and it was only 354mV
Also while I was waiting for your response i was still searching out the 3.3 line at IC908 and found that the 3.3DSP voltage that I think
is part of that is also off. Its only half traced it back to Q9301 voltages are wrong there all lower. But Q9302 is on the underside
so It would be very hard for me to test voltage there.
But if this is the wrong track let me know.
Nashou
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Post by mastertech on Feb 16, 2017 21:01:10 GMT -5
I hope you have access to ic901. If yes then check voltage at pins 1,2,3,4,5
Where are you testing for that 3.3dsp?
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nashou
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Post by nashou on Feb 16, 2017 21:16:05 GMT -5
I hope you have access to ic901. If yes then check voltage at pins 1,2,3,4,5 Where are you testing for that 3.3dsp? Ill check now. At a few places Mostly the connectors on the Display board I think CB401 and at Q9301 Nashou |
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