Hi guys,
I'm trying to repair a Linn AV 5150 subwoofer with hum. I acquired it from a gentleman here in Dallas. He tried to repair it unsuccessfully and was simply fed up with it so I picked it up trying to have some fun with it and maybe learn a little bit about electronics along the way.
When I inspected the board I saw a bad thermistor. (I was told that the board was sent to a repair shop where they replaced the capacitors and the board was tested OK). Any ways, I have the schematics for the power supply, the amp, the LED and the Fan controller. The schematic for the power supply shows a temperature sensor where the bad thermistor is. I have very limited education in electronics so I can't figure out the specs for the thermistor just by looking at the schematics. Can anyone here give me a pointer on how to take a guess at the specs of the thermistor?
BTW, Linn is no help. I sent them an email couple weeks ago... They haven't responded.
The attached PDF shows the temperature sensor on p. 3 where the thermistor is highlighted.
Any help is greatly appreciated. Thanks a bunch in advance.
I'm trying to repair a Linn AV 5150 subwoofer with hum. I acquired it from a gentleman here in Dallas. He tried to repair it unsuccessfully and was simply fed up with it so I picked it up trying to have some fun with it and maybe learn a little bit about electronics along the way.
When I inspected the board I saw a bad thermistor. (I was told that the board was sent to a repair shop where they replaced the capacitors and the board was tested OK). Any ways, I have the schematics for the power supply, the amp, the LED and the Fan controller. The schematic for the power supply shows a temperature sensor where the bad thermistor is. I have very limited education in electronics so I can't figure out the specs for the thermistor just by looking at the schematics. Can anyone here give me a pointer on how to take a guess at the specs of the thermistor?
BTW, Linn is no help. I sent them an email couple weeks ago... They haven't responded.
The attached PDF shows the temperature sensor on p. 3 where the thermistor is highlighted.
Any help is greatly appreciated. Thanks a bunch in advance.
Is to sense the temp and to cut the supply if to high.
Looks like it has to be >5k at normal temps and go under 4k if a critical (80°C ?) is reached.
Mona
Looks like it has to be >5k at normal temps and go under 4k if a critical (80°C ?) is reached.
Mona
Thank you so mumch for the pointer. Why so you think the hum changed pitch after I took the thermistor off?
The thermistor has nothing to do with hum.
I think manipulating the circuit change the condition of a bad contact (soldering ?) someware.
Mona
I think manipulating the circuit change the condition of a bad contact (soldering ?) someware.
Mona
Thanks for the response. I just heard back from Linn after sending a different email with specific question about the thermistor. They told me the thermistor is a NTC disc 33k. I just ordered the thermistor and hopefully it'll give a clearer picture after it's is installed on the board as to what causes the hum. Thanks again.