Anyone know what this is? Bullet shaped resistor?

[Crash85]

Attached is a picture of some sort of resistor or something. I have never seen it before, and it looks like it may have gotten hot. It inserts into lugs in the circuit board and then the wires are bent out. It doesnt get soldered in for some reason.

I am working on some lab equipment for my school. We have a special camera for the Gel-Dock that wont work for some reason. The fan isnt working, and I am currently searching for a replacement as well. We can't afford an $8k replacement! Im hoping the fan, and possibly whatever this is are the culprits.

Possible text on this piece: (may not be correct, very difficult to make out)
DY1
N7LS
BF72S
and the last line is completely unreadable.

Thank you!

 

[davenn]

hi there
welcome to the forums

Its not a resistor, its a thermal fuse

cheers
Dave

 

[Crash85]

Awesome! Thanks for the reply. That is very promising information. It seems that this camera uses heating elements to keep the sensor warm, but also a cooling tower to cool down. Hopefully when the fan died, it popped this fuse. I will check for continuity when I get home.

Do these numbers indicate an operating temperature at all? I was looking at radio shack for a new fuse, but the numbers dont match. Is there any website with cross reference info?


Thanks!

 

[davenn]

the temperature is normally indicated on them
just a wild guess ... the 72 may well indicate 72 deg F

Dave

 

[KrisBlueNZ]

Try Googling those numbers along with "thermal fuse". They could be part numbers and/or temperature numbers; the 72 could mean 72 degrees Celsius.

Also I think the colour of the plastic bit is different for different temperatures.

I wouldn't bother with Radio Shack; their range will be pretty limited and their documentation won't be very good. Try Digikey or Mouser. They will also give you a list of manufacturers, whose websites you can visit to learn more about thermal fuses generally.

 

[davenn]

They could be part numbers and/or temperature numbers; the 72 could mean 72 degrees Celsius.

I was considering deg C but thought that's pretty damn hot

Dave

 

[Crash85]

Im thinking it is a Cantherm thermal cutoff. The red plastic indicates a certain temp, and In Cantherms pdf, they have a DF72S part number. The 72 is the Celsius temp. Fahrenheit would be too low.


unfortunately there is continuity across the cut-off. But I am going to replace it anyways because it looks like it has gotten warm. And the couple of extra bucks to rule out the possibility of replacing an $8000 camera seems worth it! Lol

 

[(*steve*)]

I was considering deg C but thought that's pretty damn hot

Not for these devices. A quick search says they range from as low as 66 degrees C to as high as 240 degrees C.

72F is rather lower than you'd expect as these fail open, never to close again and 72F is room temperature. If you bought any of them you'd have to get them delivered by refrigerated transport!

The holding temperatures are lower, but that's a different issue.

'72' on the part number could refer to a temperature or it might not... Assuming it does, it's probably in C but may still describe the holding or the breaking temperature. I expect the breaking temperature is more likely (and will also fail safely if you get it wrong).

So it may be one of these

 

[(*steve*)]

unfortunately there is continuity across the cut-off.

Then it hasn't failed... Guaranteed.

Watch out if you need to solder it back into place. You MUST take precautions that heat from the soldering iron doesn't cause it to fail.

 

[Crash85]

it wasn't soldered into place. It just inserted through two lugs in the board and then you bend the wires out to snug it down. I went ahead and ordered a new one for peace of mind.

Will a 2 wire fan that has failed be able to trigger a safe mode in a device? Or would it need to be a three wire fan?

I remember having a tv once that wouldn't turn on because it had a dead fan. It was a 5 dollar part, and as soon as I swapped it, it worked like a champ again, but I was thinking it was a three wire fan.

 

[(*steve*)]

it wasn't soldered into place. It just inserted through two lugs in the board and then you bend the wires out to snug it down. I went ahead and ordered a new one for peace of mind.

It's a bit like replacing tyres on your car because someone told you they could go flat, but suit yourself.

Will a 2 wire fan that has failed be able to trigger a safe mode in a device?

Unlikely, but not impossible

Or would it need to be a three wire fan?

Anything is possible

I remember having a tv once that wouldn't turn on because it had a dead fan. It was a 5 dollar part, and as soon as I swapped it, it worked like a champ again, but I was thinking it was a three wire fan.

Same problem, you're thinking about what you've seen or heard of happening elsewhere and ignoring (or not looking for) evidence in the failed device.

 

[Crash85]

the only evidence to be found in the failed device at my skill level is a slightly burnt thermal fuse and a failed fan. I'll spend the 98 cents on a fuse when the only other option the manufacturer has given us is to buy a new $8000 camera.

Im definitely open to any resources that can repair CCD cameras