Component symbol on circuit board
Hi,
Can anyone tell me what the component thp601 is please. On the board it has a few coloured bands round it like a resistor
Thanks
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Hi @liamc73810
According to the parts list on p.15 of the service manual, THP601 is a PTC¹ type thermistor
¹ PTC = Positive Temperature Co-efficient = As the temperature increases, the resistance of the thermistor increases.
The part number is Sony 1-808-389-11 but unfortunately I couldn't find a replacement online when searching for the part number. You may have better luck.
What are the colours of the bands on the thermistor?
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Thanks for this. The manual I found online only has the circuit diagram. Colours are yellow, black, silver blue. Thp602 colours are different. Thanks again.
Apologies re TPH 602 no excuses its part # is 1-808 388-11 I simply misread it ;-(
I can't find the colour codes for 4 band PTC thermistors, only 3 band codes for NTC type and none are yellow - black - silver
Just testing the THP601 and it has continuity through it which I don’t think is right. Also the resistors next to it R601 and R602 have continuity through them which I also believe isn’t right. I took off IC601 and the pads were the components sat still have continuity.
Thermistors will always have continuity, unless they are faulty or are open circuit. The value of their resistance varies with the temperature.
With PTC (positive temp co-efficient) thermistors as the temp increase their resistance value increases. With NTC (negative temp co-efficient) thermistors, as the temperature increases their resistance value decreases.
Looking at the schematic R601 and R602 have resistance values of 2.4 Ohms and 39 Ohms and they are connected in parallel with THP 601 which I think has a resistance value of 0.4 Ohms - nearly a short circuit, whereas TPH602 has a value of 2K Ohms.
To know what each component actually is you would have to disconnect one side of each component from the board and then measure it individually.
