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 Post subject: Thermal Cutoffs for QSC A41 Power Amplifier
PostPosted: Jan Wed 11, 2017 11:32 pm 

Joined: Sep Fri 06, 2013 9:29 pm
Posts: 32
Location: Spruce Pine, NC
I am currently working on a QSC A41 Power amplifier that has some shorted transistors.
The unit is from 1980. The transistors have a date code of 52 week of 79.
The output wattage is 330 watts per channel.
I have found the transistors, but I am also in need of the Thermostats that are attached to the lower heat sink.
They are marked on the back Elmwood Sensors model 2450. Which I believe is now a Honeywell 2450 and solder type T101.
Then they have the following numbers stamped on them.
The 1st sensor has 88-257 L185 79/F
The 2nd sensor has 88-261 F130 79/G

What I need to know is what is the cut off temperature are these thermostats.
One works but the other one is open.
I tried heating the working one with a heat gun and measured the cut off temperature at around 100 degrees F., which I am thinking is a little low.
Any Help would be greatly appreciated.
Pics are included

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Tube Glow and Tube Sound, Awesome!
 Post subject: Re: Thermal Cutoffs for QSC A41 Power Amplifier
PostPosted: Jan Sat 14, 2017 7:29 pm 
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Joined: Jul Fri 18, 2008 10:02 am
Posts: 2039
Location: near ST Louis Mo 62002 ... yAjw3AXsuw

70 degrees C if normal or 160 F

(Conti the brain damaged robot )

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