I have a Yamaha RX V 2090 and it goes to protect mode as soon as I on it. I do repairs for amplifiers. I checked all outputs and driver transistors and other small components on the main board and cannot find any issue. I also checked voltages on the main board according to the service manual and each stage voltages are fine. Regulators also give the correct voltages. Does anyone have any experience with this amplifier? any tip to check power supply board including octocupler and other parts. how do I make sure whether problem in the main board (amplifier) or dsp board or other area. other amplifiers I can simply disconnect the dsp board and try but this amplifier I cant find any option to do that. hence dont know where the problem is. Appreciate if anyone can help.
Thanks
Thanks
i am not expert but.check psu caps?or soft start relays cirquit?check for cold joints if posible disconect amp section or other boards to locate where the problem is amp or psu.
Since about two weeks I have been checking this amplifier and couldn't find any fault. however today I am bit happy as I managed to find some issues.
I checked microprocessor's voltages in all 80 pins and below differences are found when cross check with the schematic voltages in page 42.
Pin 1 found voltage as 1V
pin 13 found voltage as 4.9 V
pun 21 found voltage as 4.9 V
pun 41 to 56 found voltage as 26.4V or near
pin 58, 59, 60 found as 2.4V
pin 61 and 65 found as zero Volts
pin 73 found as 0.2V
pin 80 found as 2.9V
rest all pins found according to the schematic voltages.
based on these could you please tell me whether the problem is in the microprocessor or some other parts associated with it
I checked microprocessor's voltages in all 80 pins and below differences are found when cross check with the schematic voltages in page 42.
Pin 1 found voltage as 1V
pin 13 found voltage as 4.9 V
pun 21 found voltage as 4.9 V
pun 41 to 56 found voltage as 26.4V or near
pin 58, 59, 60 found as 2.4V
pin 61 and 65 found as zero Volts
pin 73 found as 0.2V
pin 80 found as 2.9V
rest all pins found according to the schematic voltages.
based on these could you please tell me whether the problem is in the microprocessor or some other parts associated with it
I'm not familiar with this unit and am relying on the service manual.
The manual has a diagnostic procedure starting on page 5. What clues does it provide?
Easy check: what are DC output voltages on each power amp ahead of speaker relays?
The manual has a diagnostic procedure starting on page 5. What clues does it provide?
Easy check: what are DC output voltages on each power amp ahead of speaker relays?
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I have exactly the same problem with a high-end Yamaha soundbar and I can't find it either.
I tried everything including a hard reset but nothing worked, it's as if the processor had saved the fault in its ROM and refused to change its mind.
I wouldn't be surprised if there was a brand-specific software story.
I tried everything including a hard reset but nothing worked, it's as if the processor had saved the fault in its ROM and refused to change its mind.
I wouldn't be surprised if there was a brand-specific software story.
Pin 13 on the processor (an input, IRQ) is at logic 1, which suggests DC on an amp output. Since you don't find DC on any amp output, there's the possibility that one of the paths that signals DC fault has failed--- that it's generating a false positive. This an optimistic outlook, as repair should be should be relatively easy compared to other fault mechanisms (eg. the processor, an actual power amp defect, etc.) I hope my guess is correct.
The next step is to try find the path that is producing +5V on pin 13. I won't be in a position to offer much advice for a few days, but the block diagram on page 25 suggests that Q565---Q658 are fault detecting transistors, so I would begin exploring there. They seem to be in a "wired OR" arrangement, so any active path can trigger pin 13.
The next step is to try find the path that is producing +5V on pin 13. I won't be in a position to offer much advice for a few days, but the block diagram on page 25 suggests that Q565---Q658 are fault detecting transistors, so I would begin exploring there. They seem to be in a "wired OR" arrangement, so any active path can trigger pin 13.
Yes I have been in your shoes also. Nothing apparently wrong with circuitry. I found out that you could get software and use an interface to reset and also power up in diagnostic mode. long story short though it was telling me to update software after I did it still did not fix it. I was told that they had firmware issues with that software but would not give me the firmware bc I was not a Yamaha service facility.
Usually lots of dry joints on power supply module near front. Also, if the unit has been dropped, you might need to check for hairline fractures in the PCB's as they are very thin/brittle and break easily.
I have a bit more exploratory advice to offer.
Earlier, I referred to processor pin 13 as being related to protect mode. That may still be the case, but I suspect a more immediate path may be processor pin 17, labeled PAI, or maybe PRI--- label is too fuzzy to decipher with certainty. The wiring is a maze, so with power power off, I suggest confirming with ohmmeter tracing that processor pin 17 finds its way to R729 which connects to collector of Q655. It's on page 45, 2 H on the schematic location grid. All this to verify path from uP to Q655 collector.
If my guesswork is correct, when power is applied, you'll find processor pin 17 switches to +5V. This is due to Q655 turning on. If this behavior is confirmed, you should be able to trace the fault path from there. Could be shorted Q655 itself, or any of several paths that drive the transistor's base.
I hope this speculation proves to be helpful. Good luck!
Earlier, I referred to processor pin 13 as being related to protect mode. That may still be the case, but I suspect a more immediate path may be processor pin 17, labeled PAI, or maybe PRI--- label is too fuzzy to decipher with certainty. The wiring is a maze, so with power power off, I suggest confirming with ohmmeter tracing that processor pin 17 finds its way to R729 which connects to collector of Q655. It's on page 45, 2 H on the schematic location grid. All this to verify path from uP to Q655 collector.
If my guesswork is correct, when power is applied, you'll find processor pin 17 switches to +5V. This is due to Q655 turning on. If this behavior is confirmed, you should be able to trace the fault path from there. Could be shorted Q655 itself, or any of several paths that drive the transistor's base.
I hope this speculation proves to be helpful. Good luck!