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Receiver Running HOT with Forte I's


Snakeman99

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Total newbie here with a likely amateurish question, but why is the amp in my Technics SA-GX505 AV Control Stereo Receiver (110 W per channel at 8 ohms) running so hot when paired with Klipsch Forte I's?  I recently purchased the speakers that I'd always wanted back in the day, but have drifted out of the "hobby" for almost 30 years. I dug out my old receiver and CD player and am VERY pleased with the sound. It's just what I was hoping to hear, but there's a problem.

 

When running at relatively low volume levels (4 on a scale of 0 to 20), the top panel of the receiver above the amp gets really hot after just an hour of playing. It's so hot that I can't even rest my hand on the panel for more than a few seconds without risk of burning my skin. I don't ever remember this thing running so hot. Can I assume this is a "bad" thing?

 

The receiver has a optional Load Impedance selector switch for both 8 ohm or 4-6 ohm settings. I've tried the both settings and don't really notice much (if any) difference in sound quality or apparent heat output. Should I be looking for a new power source or do I have a bit of troubleshooting to do???

 

Thanks for your help...

Edited by Snakeman99
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18 minutes ago, Snakeman99 said:

Yes, the receiver has a cooling fan but the manual states that " The cooling fan operates at high output power levels only". Maybe I'll pull it and check the fan anyways...

Probably could use a good cleaning as well if it’s been in storage for a long time. Good luck!

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I'm beginning to do more research and think I've found my answer:

 

" If you have read other reviews about the GX505 then you would know that this amp gets extremely hot to the point it hurts to touch it."

"The only issue that I noticed with it was that it did run really hot - I won't go so far as to say you could actually cook food on it, but it was uncomfortably warm to the touch after about a half hour or so of low volume listening."

"I would be cautious of buying a used GX505 because of the overheating problem"

"Technics designed most receivers (including the SA-GX series) with a fan that is programmed to run only when the volume reaches around 50-60% of the maximum output.  Despite the fact that the units all have beefy static cooler fins dissipating heat from the power hungry amplifiers transistors, if you are listening the unit at lower volumes, you won't see the fan active meaning that the unit will get very, very hot. After about 1 hour running at 20-25% volume, the unit can easily get so hot that you can't touch its top surface - especially on the top left corner near the VFD display. A common issue with these units is that the VFD display can become dim due to solder joint cracks due to the heating/cooling cycle. Thus, if you want to use the unit for prolonged time (over 30-40min at a time), avoid the risk of solder cracks, components fatigue, etc - you need to modify the standard stock fan.

 

Edited by Snakeman99
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7 hours ago, willland said:

Not much of a tech guy but maybe due to it's age it has drifted out of bias toward Class A which would definitely cause the receiver to run hotter.

 

Bill

 

The Technics amps/receivers were biased towards class A anyway and ran hot to begin with. They had fans for a reason. If the fans quit working, or anything else within that circuit falls out of sort, the heat could easily get "out of hand" so to speak and cause the issue described. This was not unusual with a number of Technics branded amps/receivers of that era; many people thought that was a defect, but in reality that they were set up to run towards the class A side of things, which gave them a certain sonic characteristic that made them fairly popular/well liked among those who took the time to listen to them (and especially true given the price point).....but also that they oft ran pretty hot, which I never really felt all that comfortable with. Supposedly normal, though.....

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15 hours ago, Snakeman99 said:

Yes, the receiver has a cooling fan but the manual states that " The cooling fan operates at high output power levels only". Maybe I'll pull it and check the fan anyways...

If it is drifted towards A over time, could be a reason for internal fan not operating when hot, if indeed but is operating at all.

Yes, proceed with caution. Operation in over 70 degrees f, if not up to snuff, a concern.

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