GR5000 Posted September 3, 2003 Share Posted September 3, 2003 Hello everyone: I have an old Denon Pro Logic receiver (AVR-900 to be exact). A few months ago, the surround speakers simply stopped working. If I listen very closely, I can hear some static coming out of them but that is it. This occurs no matter what surround mode I pick (Pro Logic, Concert Hall, etc.). It turns out that the same problem happened years ago, when I first purchased the receiver. At the time, of course, it was under warranty, and I had it fixed. I remember speaking briefly to the person who fixed it. He explained that he had replaced a component inside (he didn't mention which one). Now the receiver would cost more to repair then it is worth. So I have resolved to attempt to fix it myself. I am armed with a multimeter and some basic knowledge of electrical circuits... I am perfectly willing to solder in a new component if need be. I'm curious to know if anyone has any advice for me going into this. Are there any websites that explain the internal layout of a receiver? Are there any resources that I could go to that may aid me in my effort? Any advice would be much appreciated. I still like this receiver, and it would be great to get it working again! Regards Greg Quote Link to comment Share on other sites More sharing options...
JohnA Posted September 3, 2003 Share Posted September 3, 2003 Buy the factory service manual. Quote Link to comment Share on other sites More sharing options...
STL Posted September 3, 2003 Share Posted September 3, 2003 I second that! Without it your chances of finding the problem are slim to none. Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted September 3, 2003 Share Posted September 3, 2003 Yes the schematic diagram and service manual for the receiver would be invaluable. However, when speakers cut-out like that or simply don't play I would suspect the speaker switching relays. Unplug the unit, remove the top cover, near when the surround speaker input terminals are located on the rear of the unit, the pins from the terminals should be connected to a PCB board inside the unit. Near where they are connected their should be a small square or rectangular box (on the same PCB), this is the switching relay. Sometimes they get stuck due to oxidation, moisture, or smoke if you are a smoker. Tap on it gently with the back of a screwdriver. See if the speakers will play afterwards, if not you will have to remove the relay's cover and spray it with some Caig's DeOxit. If the cover on it is not removable it will have to be replaced. I hope this works for you. Also prior to doing any of this check any and all internal fuses, remove them, wipe them off and reinstall them as a precautionary measure. Quote Link to comment Share on other sites More sharing options...
GR5000 Posted September 3, 2003 Author Share Posted September 3, 2003 I really appreciate everyone's advice. I'm trying to figure out where I can get the service manual. Frzninvt-- Thank you so much for your comments. The fuses seem good. I see the relay switch that you are talking about. I've tapped it a few times to no effect... I'm working on trying to figure out how to open it. In the meantime, I've done some more testing and it seems like the surround speakers are playing after all -- just at a very low volume. For example, when I run the test tones in Pro Logic, the front left, center, and front right speaker tones are very strong. When the surround tone comes on, you cannot hear -- unless you turn the volume way up. It seems like it is like this with standard prologic signals as well. For example, if I disconnect the front and center speakers, and turn the volume up (very high) I do hear the surrounds, with a good amount of static. So if anyone has any other advice given this new info. please let me know! Thanks Greg Quote Link to comment Share on other sites More sharing options...
kenratboy Posted September 4, 2003 Share Posted September 4, 2003 DO NOT TOUCH THE CAPACITORS!!! They are NOT fun Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted September 4, 2003 Share Posted September 4, 2003 Don't expect much out of those surrounds in that old Pro Logic receiver. You may be only getting like 10-20 watts to them as that was all that was necessary in the old DPL receivers. There will only be sound present in those speakers if there is a noise or effect that is sent to the rear. That receiver will not send a 20Hz-20Khz signal to those speakers like modern day receivers. The primary speakers that play in a DPL receiver are the front three, it is perfectly normal to get little or nothing out of the rears, they are strictly there for ambient sound only. Your receiver is working correctly. The rears should sound hissy and echoey in those old receivers it is the DSP chip that generates the noise. To put it bluntly Dolby Pro-Logic sucks! Get a newer receiver and you can enjoy full range sound out of the rears. Quote Link to comment Share on other sites More sharing options...
STL Posted September 4, 2003 Share Posted September 4, 2003 Frzninvt, I disagree with you; I do not think his rec'r is working correctly. Yes DPL does not send the full spectrum to the rear and it's likely powered much less than the front channels, but what he describes still sounds like a problem. I do agree with you that he should just buy a new 5.1 (or better) rec'r -- then delegate that old one to stereo use elsewhere (like a garage, bedroom, or basement). Quote Link to comment Share on other sites More sharing options...
GR5000 Posted September 10, 2003 Author Share Posted September 10, 2003 I just wanted to touch base and thank everyone again for their response. A friend (who knows far more than I do) and I worked on the receiver for a while, running several different tests. It seems like the surround processor is blown. From speaking to another person at an audio repair shop, this is not an uncommon problem with these Denon Pro Logic receivers. I'm not sure yet whether or not the processor is still available. I'm checking into that. In the meantime, I'm trying to decide whether or not to replace it. I'm beginning to come around to STL's conclusion that it is not worth fixing. So let's see what happens with it. Regardless, it's been fun working on it, and I've learned a lot through the experience. Regards Greg Quote Link to comment Share on other sites More sharing options...
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