Hello everyone,
I have a Harman kardon avr 265 amplifier. I have a problem with obvious low sound on the left channel. There is no such problem on any of the other channels, only the left channel.
Recently, when I first turn on the device, the opening screen appears and freezes. When I press any button, it goes into stand-by mode and does not turn on. When I unplug it, plug it in and turn the device on again, it turns on and works without any problems.
Here's what I've tried so far regarding the sound problem in the left channel:
-different speakers. It didn't work.
-different cable. It didn't work.
-I tested it from different analog and digital inputs, it didn't work.
What do you think is the problem?
Thanks in advance to everyone who will help.
I have a Harman kardon avr 265 amplifier. I have a problem with obvious low sound on the left channel. There is no such problem on any of the other channels, only the left channel.
Recently, when I first turn on the device, the opening screen appears and freezes. When I press any button, it goes into stand-by mode and does not turn on. When I unplug it, plug it in and turn the device on again, it turns on and works without any problems.
Here's what I've tried so far regarding the sound problem in the left channel:
-different speakers. It didn't work.
-different cable. It didn't work.
-I tested it from different analog and digital inputs, it didn't work.
What do you think is the problem?
Thanks in advance to everyone who will help.
Welcome to the forum!
Do you have any repair experience, equipment, tools, etc?
There's a good quality service manual on the site listed below. I tried to attach, but the file is too large.
Within the manual, there's a procedure for resetting the processor. I doubt this will resolve your problem, but it's simple and worth a try.
The facts that the problem seems isolated to the left channel and seems to recover readily with cycling of power is encouraging. I can offer some very wild guesses about the problem, but I'd like to learn more about your comfort level regarding diagnosis and repair.
Good luck!
https://elektrotanya.com/harman_kardon_avr265-230_rer0.pdf/download.html#dl
Do you have any repair experience, equipment, tools, etc?
There's a good quality service manual on the site listed below. I tried to attach, but the file is too large.
Within the manual, there's a procedure for resetting the processor. I doubt this will resolve your problem, but it's simple and worth a try.
The facts that the problem seems isolated to the left channel and seems to recover readily with cycling of power is encouraging. I can offer some very wild guesses about the problem, but I'd like to learn more about your comfort level regarding diagnosis and repair.
Good luck!
https://elektrotanya.com/harman_kardon_avr265-230_rer0.pdf/download.html#dl
Thank you,
I have repaired a very simple amplifier before, but I have never repaired a device as complicated as this.
If we can find a solution to the problem, I can have it solved by someone who is skilled and equipped in this field. One of my main problems here is that the people I show the device to do not have any knowledge about the problem. Some said it was caused by the integrated circuit, some said it was caused by a part called the distributor, and they did not give a guarantee that the problem would be completely solved. That's why I wanted to do it myself.
I tried resetting the processor but it didn't work.
Thanks for the document.
I have repaired a very simple amplifier before, but I have never repaired a device as complicated as this.
If we can find a solution to the problem, I can have it solved by someone who is skilled and equipped in this field. One of my main problems here is that the people I show the device to do not have any knowledge about the problem. Some said it was caused by the integrated circuit, some said it was caused by a part called the distributor, and they did not give a guarantee that the problem would be completely solved. That's why I wanted to do it myself.
I tried resetting the processor but it didn't work.
Thanks for the document.
I disassembled the amplifier neatly. Now all the capacitors and processors are visible in front of me, but I don't know where to look for the problem
There are a few swollen capacitors that catch my eye, I think I'll start by measuring their values.
I surmise you have have soldering and repair skills.
Do you have a voltmeter or any other equipment? Are you comfortable probing live circuitry and can you be safe doing that? I don't want you to risk yourself or further damage to your equipment.
From your description, it sounds like you've localized the problem to that one power amp section. It could be a defect in the PA itself, or it might be a problem in the fault monitoring circuit--- we can try to determine which. I have the impression the microcontroller behaves in a sensible way and isn't really under suspicion?
Do you have a voltmeter or any other equipment? Are you comfortable probing live circuitry and can you be safe doing that? I don't want you to risk yourself or further damage to your equipment.
From your description, it sounds like you've localized the problem to that one power amp section. It could be a defect in the PA itself, or it might be a problem in the fault monitoring circuit--- we can try to determine which. I have the impression the microcontroller behaves in a sensible way and isn't really under suspicion?
I have a voltmeter and soldering equipment. I'm not sure if I can control a live circuit, an accident could possibly happen.
How can we test for the causes of the problem? If necessary, we can also test the microprocessor. Even if I cannot do these, if you guide me, I can at least convey what I want to do to someone who is skilled in this field.
I can send photos of the motherboards and other components if you want.
How can we test for the causes of the problem? If necessary, we can also test the microprocessor. Even if I cannot do these, if you guide me, I can at least convey what I want to do to someone who is skilled in this field.
I can send photos of the motherboards and other components if you want.
If I understand correctly, your original post indicated that the amp can be coaxed into working, and then behaves properly. After being turned off for a period, the amp then has trouble restarting with trouble evident in only the left channel. But it can be power cycled and again will behave normally. Is this a good description?
Since the amp seems to work OK with a little prodding, I recommend against replacing caps until the amp is again working normally. Then you can replace suspicious caps, one or two at a time with rechecks for normal operation. Replacing caps while the amp is in an erratic state risks confusion if a new problem arises--- you don't know if a new problem has been introduced during repair or if the original problem has worsened.
I suggest some initial testing with no speakers or test loads applied. Monitor DC output on speaker terminals on each channel, with special scrutiny on the problem left channel. What is Left output voltage? Is the output voltage more erratic than other channels? Is DC offset drift behavior worse immediately after power on?
That next test is to perform bias current adjustment as described in page 151 of the service manual. Any surprises? Repeat inspections outlined above.
If everything looks nominal with the PA but the start-up problem persists, then there's increased suspicion of the protection circuit. I'll need to study a bit, but will try to devise some experiments to confirm and localize the defect.
Since the amp seems to work OK with a little prodding, I recommend against replacing caps until the amp is again working normally. Then you can replace suspicious caps, one or two at a time with rechecks for normal operation. Replacing caps while the amp is in an erratic state risks confusion if a new problem arises--- you don't know if a new problem has been introduced during repair or if the original problem has worsened.
I suggest some initial testing with no speakers or test loads applied. Monitor DC output on speaker terminals on each channel, with special scrutiny on the problem left channel. What is Left output voltage? Is the output voltage more erratic than other channels? Is DC offset drift behavior worse immediately after power on?
That next test is to perform bias current adjustment as described in page 151 of the service manual. Any surprises? Repeat inspections outlined above.
If everything looks nominal with the PA but the start-up problem persists, then there's increased suspicion of the protection circuit. I'll need to study a bit, but will try to devise some experiments to confirm and localize the defect.
I may have expressed it wrong, English is not my native language
The sound problem in the left channel is a constant problem. It is not something that depends on the operation of the amplifier.
I have been experiencing the sound problem in the left channel for about 2 months, and the problem of turning on and freezing has been around for about two weeks.
Thank you for your suggestions. I will try it and report the results.
The sound problem in the left channel is a constant problem. It is not something that depends on the operation of the amplifier.
I have been experiencing the sound problem in the left channel for about 2 months, and the problem of turning on and freezing has been around for about two weeks.
Thank you for your suggestions. I will try it and report the results.
I measured the value of the transistors connected to the cooler and I suspect one of them (the one whose photo I attached, underlined in blue in the D1560 section on the paper).