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
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
