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SA-DX1040 Technics Receiver switching to "Protected Mode"

Hi there,

My 6-year-old Technics receiver has recently developed a problem with switching into protected mode (Overloaded appears on the display) after being switched on for a few minutes. Now this model ran extremely hot (couldn't even touch the top of the case) but this was apparently perfectly normal according to the people from Panasonic and other stuff I've read online. Unfortunately, I think the years of heat probably fried something in there.

I've tried the following without success:

-Switch speakers from channel A to B

-Replace speaker wire

-Replace speakers and try channel A and B

-Turning off both channels still make the receiver go into protected mode

-Running the amp without speakers attached

Since I suspected that this issue might be heat related I replace the fan at the back of the receiver with a 80mm computer fan wired to a 12V plug-in power supply. To my surprise, the receiver did not go into protected mode the receiver stayed cool to the touch. Although this work around enables me to use the receiver without any problems, I find it very annoying to have to plug in the fan every time I want to listen to music. Additional the hum of the fan is audible when the audio is at low volume.

I though about bringing it in to a shop for repair but most shops want $80 just to open the case...it gets more expensive from there. This is probably not worth the money for a 6-year-old receiver. I've read on the forums that Technics receivers a prone to soldier connection failure but I'm not sure where to start looking.

Any advice would be greatly appreciated.

Cheers,

Marc Savage

Reply to
Marc
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Marc: $80 to just open the case???? I don't think so..... usually shop charges for estimates on a stereo reciever would be in the area of $25 to $50 depending on the receiver and the shop... and of course, the estimate charge will apply to the repair invoice if you should choose to go ahead with the repair. TAKE your receiver to a different shop and get a first hand idea of what they charge..... phone calls won't do the trick.... TAKE it to the shop... and if reasonable, leave it there for an estimate and/or repair...-- Best Regards, Daniel Sofie Electronics Supply & Repair

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Reply to
sofie

Marc: $80 to just open the case???? I don't think so..... usually shop charges for estimates on a stereo receiver would be in the area of $25 to $50 depending on the receiver and the shop... and of course, the estimate charge will apply to the repair invoice if you should choose to go ahead with the repair. TAKE your receiver to a different shop and get a first hand idea of what they charge..... phone calls won't do the trick.... TAKE it to the shop... and if reasonable, leave it there for an estimate and/or repair...-- Best Regards, Daniel Sofie Electronics Supply & Repair

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Reply to
sofie

I'd suspect you're right. Most electronic components' MTBF are spec'ed at

85C, some are available in a higher temp model good to 105C. If it's too hot to touch that's BEGGING for something to fail. If you're lucky you've only dried out some (or all) of the electrolytic capcitors, particularly the ones in the power supply. If you're not lucky you may have fried some proprietary, impossible-to-find IC available only to "authorized service centres". There may be a thermal sensor someplace inside the unit which has degraded over time; could be that the output power transistors have aged and their thermal safety is tripping.; any number of other components. I'd look at a fan solution as you did. If the amp is designed with such low efficiency that it's got to burn off tons of excess wattage as heat, you have no choice but to get rid of the heat. Or get rid of the amp.

Do you mean that you can hear the fan's mechanical movements, or that the fan's motor noise is being amplified by your receiver and piped through the speakers as background? Different problems, different solutions. If it's a noisy fan and not causing any interference, look at buying a quieter one. Plug the fan PS into one of the "switched" outlets on the back of the receiver so that it turns on when the amp turns on.

You can generally diagnose solder-joint problems by wiggling the various boards. It's obvious if you wiggle a board and a problem occurs every time. Given that cool=works and bad=broke I'd guess that it's a heat-related component failure and not cold solder joints but then, I'm often wrong.

Reply to
Dave

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