Can anyone tell me what this is?

I have nothing else, sorry - just the part. No markings or labels on it.

Came out of a Brother laser printer- I was clever enough to salvage neat-looking parts from it, but not clever enough to document where each was taken from...

There was a heating element inside one of the rollers. Near that roller were:

1) a thermostat (CH-152-35),

2) this thing,

3) a G16C Thermistor in an amber sheet housing with a black base similar to the one on the posted item.

Exact locations unknown, I didn't document it. But all near the heated roller.

ItemToBeIdentified Black marks are toner residue not burn marks. Wiped them off the outside of the amber plastic.

Back side of unknown component A better look at the side not shown well in the last pic.

Thermostat near posted item The thermostat. I love part numbers, makes newbie research easier.

Thermistor near posted item The thermistor. Again, I love it when they print useful part numbers on stuff that you can Google!

  • 7
    \$\begingroup\$ It's called a "ruler". Asfor the thing at left, it's hard to say. \$\endgroup\$ Feb 27, 2018 at 22:03
  • \$\begingroup\$ Which part of the printer was it in? \$\endgroup\$ Feb 27, 2018 at 23:25
  • \$\begingroup\$ It was buried near the heating tube part - but there was also an actual thermostat (CH-152-35) down there. \$\endgroup\$
    – 111936
    Feb 27, 2018 at 23:44

4 Answers 4


It is a thermistor.

I am posting HOW I found out, for any future readers:

The answer wasn't forthcoming by visual inspection of exchange members, and my prior Googling had not yielded useful results.

The problem was that I and others here were focused on the picture of the part itself. I changed focus to the printer (in my case a Brother HL-5240), and any documentation I could find.

I accidentally found the service manual for it. In that manual were the circuit diagrams. It took a very long time for me to read through them and figure out how to follow the circuit as it went through a few different drawings. (I'm a novice and this is the first large diagram I've tried to use - 9 pages of drawings!).

Eventually I found a symbol for a thermistor (the resistor zigzag symbol inside a closed oval), and googled the number next to it: "TP835". And sure enough - I got Google hits with pictures of similar parts. Had to look at a bunch, and eventually I found matching items.


It looks like it could be a bimetallic temperature switch. These are made from two metals that have different expansion coefficients so that they bend when heated up. They are often used to turn something off when it gets too hot. It looks like it is supposed to be connected to some external contact on the black rounded bump.

  • 1
    \$\begingroup\$ That doesn't look like a bimetallic strip. \$\endgroup\$ Feb 27, 2018 at 23:27
  • \$\begingroup\$ Black base is plastic of some sort - was mounted in a plastic of some sort receiver. So black bit is just a holder for the bronz-y bit. \$\endgroup\$
    – 111936
    Feb 27, 2018 at 23:46

The two leads imply that it is a temperature or pressure detector, changing its resistance with pressure or temperature. The dark spot is the sensing element.

The long copper leads are just for spacing, and an elastic behavior, which leads me to think it is for position sensing.

It may be functional if the OP uses an ohm meter to test it.

NOTE: If the OP says there is a temperature sensor already there, then this device is not likely another temperature sensor. If so, it would be the tubular 'bullet' type used as an emergency cutoff. The material looks damaged-metallic spray, as if it were a fusable link designed to fit in a tight spot. If so it is a custom design.

Picture of molten metal with scorch or burn marks: enter image description here

  • \$\begingroup\$ Editing OP to add info related to other components found near it. \$\endgroup\$
    – 111936
    Feb 27, 2018 at 23:53
  • \$\begingroup\$ So are you thinking 1) sensor [Thermistor], 2)normal shutoff [thermoSTAT], 3) emergency shutoff [the item I posted] ? Thus maybe a fuse? I see how that makes sense - does the item really look like one? \$\endgroup\$
    – 111936
    Feb 28, 2018 at 0:07
  • \$\begingroup\$ Look at the zoomed-in picture. Molten metal with scorch and burn marks. Whether it was a emergency fuse or not, it is blown. \$\endgroup\$
    – user105652
    Feb 28, 2018 at 0:09
  • \$\begingroup\$ @Nixt. Did you find any damage or burn marks anywhere? \$\endgroup\$
    – user105652
    Feb 28, 2018 at 0:11
  • \$\begingroup\$ Will add one more image in a sec - of the other side of the object. No burn marks or other signs of damage aside from one capacitor in a completely different part of the printer being 'bulged' at the top. The printer was fully functional when dissected! It had no $ value left in it so got recycled here before going to the 'pro' electronics recycler. \$\endgroup\$
    – 111936
    Feb 28, 2018 at 0:16

From the heavy crimped-on connector lugs in the thick white wiring, it seems this is a spot heater.
The small thermal sensor possibly senses near the spot heater- sensor looks like a solder dot.

The can is similar to a variety of thermostats (switching according to temperature) that might be associated with whatever is being heated.

  • \$\begingroup\$ A spot heater that burned out? Very possible. \$\endgroup\$
    – user105652
    Feb 28, 2018 at 0:32
  • \$\begingroup\$ I'm confused - there are no black wires on any of the three components shown. Two wires, both white, on the object I'm asking about. \$\endgroup\$
    – 111936
    Feb 28, 2018 at 0:55
  • \$\begingroup\$ @Nixt -My fault: fourth pic 'the thermistor' looks like white and black (probably just shadow of the white wire). \$\endgroup\$
    – Whit3rd
    Feb 28, 2018 at 5:09

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