Denon S-302 DIY Repair for Overheating, lockup, freeze - AVS Forum
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post #1 of 8 Old 02-03-2011, 11:51 AM - Thread Starter
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This is a DIY repair for a US model Denon ADV-S302 manufactured September 2007. I'm not sure how similar the international versions are.

I picked up a used Denon S-302 a little over a year ago and love the sound and simplicity of the unit. However, don't let the clean lines deceive you from its capabilities.

The only downside is the absence of blue ray built in and a nagging design issue (at least in the US and my opinion). Several have commented on the S-302 freezing or locking up with the only remedy being to unplug from the wall receptacle or disconnecting the 25 pin back connector from the bass/amp unit. As soon as the unit cools down everything appears normal until it overheats again. My unit would lockup after about 10 minutes while watching a DVD. My family wasn't impressed with my latest toy so I set about finding a resolution.

My unit was used and not covered by a warranty. If you have a warranty use it. I did check into returning the unit for repair but wasn't keen on paying for shipping and not guaranteeing a reasonable repair. Call me gun shy after getting burned recently by Casio but I digress. What did I have to lose at this point if I took it apart and ended up with spare parts after reassembling? Not much, so I ordered a repair technical manual online for about $10 and went about trying to decipher hieroglyphics.

The short answer that I discovered is the 12 volt fan in my unit was being powered at 8.5 volts and not providing adequate airflow. Jumpering some circuits bumped the voltage to 12V and greatly improved the airflow. I also clipped one leg disabling the over temperature thermistor feeding to the main microprocessor so it won't cause a shut down. The downside of disabling the thermistor is that it may permanently "nuke" if it overheats.

Read on if you want the details of the modification. It's only been one day so far but I've successfully made it through several DVDs and all other functions work unchanged.

I quickly (ha!) honed into the microprocessor pinouts for over temperature detection, fan on/off, and fan high/low speed. Why the fan would ever need to be off when the S-302 is turned on baffles me. I can understand the high/low feature but the circuitry has some components purposely missing to function like the technical manual schematics show. Call it a late production cost saving measure (&#$!).

My hands are not steady enough to measure the fan high/low signal at the IC201 microprocessor pinout (#67 if you have bigger stuff than me). The closest component I could get to showed the fan high/low signal was always high which kept the fan in low speed and hence only 8.5V driving the fan!

The fan on/off signal from pinout #66 of IC201 did appear to function correctly. When the S-302 was turned on, the signal (again from the closest component) correctly turned on the fan.

Okay, so now I only had to figure out how to best rewire the fan to 12V without overloading a power source. There are several 12V sources available: on DB25 power supply board, video boards, and the intended source on the main board. I could have snagged a jumper from the main board 12v source but wanted to keep some of the integrity of the fan circuitry functionality. Besides butt splices right to the fan isn't very elegant. My solution was to jumper from the 12V leg of fan circuitry TR202 to the positive leg of fan circuitry capacitor C278. The fan now functions with 12V and higher air flow. Voila!

The next step I did may not be wise but figured I wanted to ensure the microprocessor wasn't being too sensitive in it's over temperature shutdown. I clipped a leg of thermistor S201 so it never feeds an over temperature condition to the microprocessor. This might cause permanent damage if it overheats but the S-302 unit wasn't doing me any good by only watching 10 minutes of a DVD. Call this the belt and suspender solution.

The S-302 ended up one screw short after reassembly which is better than other projects. It also seems to work fine and no longer locks up. Time will tell though. For now, I'm back to enjoying my Frankenstein S-302 as it was intended.

I would rate this repair as moderate. You do have to dissect the S-302 to the bowels and the components are mostly surface mount which makes it difficult (at least for me) to get a good solder connection.

Enjoy
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post #2 of 8 Old 02-03-2011, 11:58 AM
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Looks like a decent kludge to get the fan working, but I certainly wouldn't call what you did a repair...
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post #3 of 8 Old 02-04-2011, 08:37 PM - Thread Starter
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Gee, thanks, I think... It wasn't working before but now works; guess it must not be repaired
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post #4 of 8 Old 02-05-2011, 03:36 PM
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Quote:
Originally Posted by S-302 Abuser View Post

I clipped a leg of thermistor S201 so it never feeds an over temperature condition to the microprocessor. This might cause permanent damage if it overheats...

Great "repair"... You got it running enough that it can destroy itself.

Like I said, decent kludge, but not a repair...
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post #5 of 8 Old 02-05-2011, 05:05 PM - Thread Starter
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Colm,

Okay, I'm all ears and smiles. How would you repair given the conditions I described?

Clint
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post #6 of 8 Old 02-05-2011, 06:39 PM
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Who knows? I might do just what you did, except cutting the lead on the thermistor. I still wouldn't call it a repair, but rather a kludge. If you took your car to a mechanic because it was overheating, and instead of finding the cause and fixing it he wired the fan so that it was always running at full speed, would you call that a repair?
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post #7 of 8 Old 05-07-2011, 11:43 PM
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Hi S-302 Abuser

I am looking for the 302 service manual, can you please advise me where to purchase and download ?

Best Regards
Peter
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post #8 of 8 Old 07-02-2013, 03:59 PM
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Related issue, I think ...

I recently bought a broken s-302 (completely dead), hoping I could repair it. I have secured and searched the service manual, phoned Denon, phoned the authorized repair facility, and still don't really know the following, which I'm hoping someone can help with:

Starting with all cords disconnected, when the subwoofer power cord is plugged in, the red "protection" light on the back of the subwoofer turns on and stays on (very bright). Does this mean there is a problem with the subwoofer / power supply? I had hoped that this would isolate the problem to the subwoofer, but the Denon shop guy said not necessarily.

When the system connector cable and the S-302 receiver are then plugged in, the red light goes out. The receiver then shows no signs of life at all.

Does the red light give any clues as to whether the problem is in the subwoofer or in the receiver? What is the light supposed to do if there are no problems? The manual says it will flash if it overheats, but says nothing about staying on or staying off.

If someone has a working system, can you tell me whether the red light is on when everything (except power) is disconnected, and then if it is on when the S-302 is connected?

Does the Protection light ever turn green? (The Denon guy said it would, but nothing else I have seen says it does)

Thanks!
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