Technics SE-A100 Thermistor value - help needed

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Hi Everyone,

I have been looking to find some information on a thermistor that is used in a Technics SE-A100 amplifier. The component in question is TH151. There is no resistance value or part number listed in the service manual.

Can someone help me identifying this part ?
 

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Hi MAAC0,

Thanks for trying to help.

I can not measure anything as I don't have this thermistor. I want to source a replacement component.

Strangely another and different thermistor used elsewhere in the circuit is listed with value and part number in the documentation.
 
Hello,

There's a nice person in Germany who posted some detailed pictures here. As far as I can tell, Technics decided to replace R153+Th151 combo with a 470 Ohms(?) resistor. You can measure that resistor for sure and, knowing from schematics that R153 is 1.8KOhms, you'll have thermistor's value at 20*, as @MAAC0 said.

Regards,
Cosmin
 
Hi Cosmin,

Thanks for trying to help me and for the link.

As I had indicated in my previous post, I do not have the thermistor. I am looking for one or for a suitable replacement. Believe me, if I had one, I would have measured it already.
 
Hi MAAC0,

thanks again for trying to help.

So I guess you measured something with the circuit intact. I am not sure if this measurement would be valid.

What was the temperature at the time you took this measurement ?

Can you remeasure at two additional temperature points ?

Ideally, the thermistor is measured by itself without the circuit around it.


So both are in parallel. 1800 in parallel with 640 gives 472 Ohm.
I would try a 630 or 640 Ohm thermistor.
 
Hi all,

I think that position of VBE multiplier made Technics to not use the thermistor in the final product. This transistor is not directly placed on heatsink but on a prolongation of it... and so, is placed in an area (volume in fact) which otherwise would be covered by thermistor. If I'm right, Th is not needed indeed.

Regards,
Cosmin
 
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