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Denon DRA-685
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Peenerpunch
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PostPosted: Sat Sep 09, 2006 2:26 am    Post subject: Denon DRA-685 Reply with quote

I also have a Dra-685 that has began going straight to protection as soon I turn it on. I have looked all over for a schematic diagram so that maybe I could fix the problem but have thus far been unsuccessful. If anyone knows where I might get one please let me know or if you know the problem and know what needs to be done please let me know. Thanks.
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Adepera
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PostPosted: Sat Jan 27, 2007 1:00 am    Post subject: Denon dra 685 Reply with quote

I have the same problem with my DRA-685, did you solve it? Let me know how!
Thanks
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MitchB



Joined: 28 Apr 2007
Posts: 1

PostPosted: Sat Apr 28, 2007 2:22 am    Post subject: DRA 685 "Protection" Error Reply with quote

R105 and R106 are underrated resistors. In my receiver, both of them failed.

Replace them both with 1.0 Ohm, 1 Watt Flameproof resistors.

To verify that this is the problem, measure between chassis ground and the front board connector labeled "+15V" and "-15V". If either or both of these voltages is/are missing, the resistors have likely failed.

The correct repair would be to fully disassemble the receiver and solder from the bottom side of the board, but you can test your fix by clipping out the old units leaving leads long enough to solder new resistors to.
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PostPosted: Tue Oct 28, 2008 8:32 pm    Post subject: Reply with quote

Thanks for the info, my Denon has these symptoms. However, my eyes nor my son's good eyes can find r105 106. If there's anyone out there, can you give us a clue? thanks
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Wed Oct 29, 2008 1:37 am    Post subject: Reply with quote

Looking from the top of the board, both R105, R106 are next to a CN2 connector. As it was said, use a 1 ohm, 1 watt resistor in place of them. They are underrated and simply act as a protection for plus/minus 15V lines.



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jkadhfjkafjh
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PostPosted: Mon Aug 23, 2010 3:27 am    Post subject: Similar Issues with DRA-685 Reply with quote

I had the persistent "PROTECTION" at start as well. When I tested the +15 and -15 volts, they were there. I still replaced R105 and R106 on a hunch. It completely fixed the problem. Took 30 minutes!
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rx35285



Joined: 01 Sep 2010
Posts: 1

PostPosted: Wed Sep 01, 2010 12:28 am    Post subject: Denon DRA-685 repaired! Reply with quote

I had bogus voltage readings at CN1 so I snipped out both R105 and R106, which were pinned very close to the board. I couldn't get reliable readings on the old ones. Practically had to burn holes in the board to get the new resistors installed, but it WORKED! Got about 15.5 V +/- at CN1.

Mitch and vtech, you saved me ~$200 and a couple of weeks without a receiver. The parts cost me $4.07 (they are monsters compared to OEM) and I enjoy this sort of tinkering. This is my first time on the site and I need to find a way to contribute in appreciation for your contributions.

Many thanks!
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Dave in Cedar Falls, Iowa, USA
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Wed Sep 01, 2010 2:24 am    Post subject: Reply with quote

You are welcome. Glad to be of help Very Happy
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togusdream
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PostPosted: Sat Sep 11, 2010 5:16 pm    Post subject: DRA 685 protection message Reply with quote

Thought i had hit the jackpot with your info....snipped out the R105 106, but receiver still goes to PROTECTION after showing a good display for 5 or 6 seconds....any other suggestions? I have disconnected speakers, should i have? Just can't give up on this great equipment!
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Sat Sep 11, 2010 7:13 pm    Post subject: Reply with quote

There was no need to disconnect the speaker and keep in mind that the missing plus/minus 15 happens to be one of the many possibilities for the PROTECTION. In your case, you may have a bad channel or perhaps a syscon problem or even another missing supply voltage?
Do you have a multimeter and are you capable of basic troubleshooting? I used to work with many of these units and strictly volunteer my time here to help out. Due to the limited time, you may not get an answer right away.

One way is to monitor the DC voltage on the base of the output transistors. (Q15~Q18). Make sure the volume control is set to min and be careful for the probes not to slip and short out against the adjacent connections; Normal reading should be below 1 volt (plus or minus in respect to the transistor type) minus for the 2SAxx & plus for 2Scxx. There should be a close balance between the two base voltages which usually indicates that output transistors are still good...
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