| Electronics > Repair |
| Marantz SR5200 amp damaged center channel + DAC issues |
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| mzacharias:
It's been a while but if I recall correctly, I just looked for output at the related op-amps, and then replaced the CS4391 that was feeding it. Since then - I've seen the problem so many times I just replace IC720. Haven't missed yet. It was a very common problem. P.S. They had a lot of problems with the volume control rotary encoders, too. Obviously doesn't directly cause your problem, and you would see the poor response on the VFD display. |
| poot36:
In my case would IC720 being bad result in no sound out even in surround mode due to the way it is attached to IC719? If I remove it would I at least get sound from the surround channels but not the FR and FL channels? |
| mzacharias:
As best as I can recall - yes, no or low sound in any mode, and can be somewhat intermittent. You could try just re-flowing the solder on IC720. I always wondered if it was a solder problem; the chip gets a little warm - but I have always just replaced the chip. I'm retired now but even still, I keep one of those chips on hand. They're cheap, and I really like the SR-7200 model. If one becomes available for very little, I might acquire another. |
| poot36:
Well you were right, IC720 is part of the problem. It was shorting out the SCL line of the I2C bus causing multiple chips to not work. I have removed it. Now I have data on the 3 SDIN pins on IC719 and SDATA on the IC720 pin when switching between the surround modes. I still don't have sound from the surround channels though and when changing the surround mode I still get unwanted sound coming out of all channels like the mute is working backwards. I will order a replacement chip but it will probably take about 2 months to get here from China. In the meantime why are the surround channels not working correctly? |
| mzacharias:
--- Quote from: poot36 on November 29, 2018, 06:22:52 am ---Well you were right, IC720 is part of the problem. (snip) In the meantime why are the surround channels not working correctly? --- End quote --- Don't know really but I'd be surprised if all was not well after you get that IC720 replaced. When the receivers were still pretty new, Denon tech support could only say the DSP board was bad, but they didn't stock them so if under warranty the receiver just got replaced, otherwise the customer was on his own. Much later, during some slack time in the shop, I was able to troubleshoot as I said before - looking at the appropriate op-amp outputs, then referring back to the chip that was driving them - IC720. Since then I've replaced at least 1/2 dozen for the same problem. Other than this and the front panel tact switches, the receivers are quite reliable in my experience. The tact switches are important, though. They can cause a variety of symptoms, no response to a source selection, wrong source selected, lock-ups, etc. By the way - here is the reset procedure. It is undocumented both in the user manual and the service manual, if I recall correctly. 1. Unit unplugged 2. press-hold A/D , F/P, and Dimmer. 3. Plug in, hold til unit turns on. Unit is reset if initial volume is -75db |
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