What thermal fuse temp would be safe to use here?

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Joined: 22/10/2019
Location: Australia
Posts: 816
Posted: 01:35am 27 Jul 2023      

As some of you may know, I earn my living fixing circuit boards and regularly get asked to fix boards I've never seen before and with zero documentation.

Anyway, the local meatworks brought in this board with an open circuit thermal fuse  ...  and they had a replacement for me to fit. Problem is the replacement is 184 degree and I'm pretty sure that's not a good idea.

See image, but it sits alongside a 22 ohm 7 watt resistor and inline with a normal fuse  ...  so I expect that it's meant to fail if the resistor gets too hot.

The board has 46 scratched onto it  ...  but the old fuse has been damaged and can only really read the 6 and degree marks. The only fuses I can find ending in '6' are 76 or 126 or 216  ...  and the lowest I can find is 70  degrees.

What temp would you choose? Thanks.