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Post by fuxtor on Aug 28, 2016 17:56:22 GMT -5
I am getting as follows
Pin 34
Standby + 1.8 mV
Power on +5.2 mV
Pin 71
Standby and power on +3.3dcv
cp404 harness disconnected still
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Post by mastertech on Aug 28, 2016 19:24:22 GMT -5
Ok, that is what should of happened. So the circuit is working properly on this board.
So remove that solder from that resistor location so it is back to original.
Reconnect the harness to CP404.
Now you need to go to the amp board to look for the problem. Since you have a problem on both pins 34 and 71 you must have at least 2 channels with a problem. So you must disconnect each channel 1 at a time and test the pins for voltage after each disconnect. I will give you the list of resistors that you will have to remove to disconnect each channel. Hopefully you can remove resistors without much disassembly because it would be best to test the pin voltage after each resistor to know which channels allow the pin voltage to rise to the 3.3v that you got when you soldered the 2 pads. Here are the resistor list: R542,R499,R455,R412,R585,R628,R671.
If these resistor were in reach with your DMM probe while assembled and powered on then you could test for voltage variances to locate the bad channels. But it is usually not within easy reach.
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Post by mastertech on Aug 28, 2016 20:24:42 GMT -5
I was just thinking and before you do the above test you should probably check a couple resistors on that CPU board first just to make sure they are not blown. They would be R253,R254,R255. They should each ohm test at 100 ohms.
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Post by fuxtor on Aug 28, 2016 20:54:13 GMT -5
I was just thinking and before you do the above test you should probably check a couple resistors on that CPU board first just to make sure they are not blown. They would be R253,R254,R255. They should each ohm test at 100 ohms. They test good, so back to previous testing.... |
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Post by fuxtor on Aug 28, 2016 23:23:35 GMT -5
I was actually able to take voltages from all the resistors!!
They were all reading basically 0 dcv
except for R499 which I got a reading of - 53dcv.
I also noticed that R493 was burnt , I'm pretty sure it occurred when the solder bridge was intact and the unit was staying on, I noticed smoke and turned power off. Afterwards unit shuts off after 3 seconds as before.
Edit: I just thought to mention that i tested each resistor with a lead on both ends and then applied power.
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Post by mastertech on Aug 29, 2016 9:07:33 GMT -5
Looks like you at least have a problem with the center channel. Which channel have you already made repairs on?
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Post by fuxtor on Aug 29, 2016 22:56:34 GMT -5
Q422 was replaced along with the pair of emitter resistors R474 and R475 . R 483 was also no good and replaced.
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Post by fuxtor on Aug 30, 2016 21:22:06 GMT -5
Tonight I will recheck components on center channel.....
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Post by fuxtor on Aug 30, 2016 21:22:46 GMT -5
Tonight I will recheck components on center channel..... I believe this is the front right channel... |
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Post by fuxtor on Aug 30, 2016 21:26:36 GMT -5
Ignore that last comment ( was meant to answer Master techs previous comment on which channel was replaced )....
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Post by fuxtor on Aug 31, 2016 8:32:32 GMT -5
Well, right again Mr.Mastertech...., Found a bad center channel transistor along with some fried resistors. Replaced the transistor and a few of the resistors on that channel. I will check for more bad stuff later today and check in.
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Post by fuxtor on Aug 31, 2016 22:36:09 GMT -5
found a few resistors to replace on center channel, put back together and still getting the overheat shutdown? where do you think i should keep checking? i checked over the smaller signal transistors but they seem all good....
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Post by mastertech on Aug 31, 2016 23:11:05 GMT -5
Are you still getting voltage on R499?
Did you value test R493?
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Post by fuxtor on Sept 1, 2016 8:25:58 GMT -5
I still have voltage at R499 , I will check for the value of the other resistor tonight..... Excuse my lack of hindsight! I should have retested the same way afterwards as your instructions in previous posts. Essentially if I have no voltage at resistors you listed I assume the components for that channel should be good yes?
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Post by fuxtor on Sept 2, 2016 18:37:45 GMT -5
OK, barely any voltage at R499. Burnt resistor R493 replaced and measuring 33 ohm. Still stuck at Overheat message, gone through basically every component? Is it possible that something keeps frying from powering the unit on?
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