mcintosh 240 part identification for repair

[jasonv]

my amp didnt turn on when i plugged it in and found out the piece of metal was the issue. it looks like the weld broke apart as when I clamped it together the amp turned back on.

does anyone know what part this is?

is it soldered on or welded on? looks like a piece of metal for all the ground wires to go to.

 

[Chris Hornbeck]

That's a thermistor; Mc variously specifies it as " >25 Ohms cold" and "79 at 25C". Exact value isn't terribly critical.


YOS,
Chris

 

[jasonv]

would you recommend replacing it or just soldering it back on? i cant find original mcintosh thermistor online.

 

[jasonv]

just did a quick search on google. looks like this is the replacement.

https://www.mouser.ca/Circuit-Protection/Thermistors/_/N-axfus?Keyword=CL-90&FS=True

but the specs are 120ohm which is very different than 25.

 

[ahankinson]

The “cold” resistance doesn’t matter very much, since the resistance decreases as it warms up. It’s basically a slow start mechanism to give the tubes time to heat up before they start conducting. The resistance will decrease to near zero when it heats up. I wouldn’t go below 25 ohms, but higher values just mean a slightly longer warmup time.

You could try a CL-190 if you wanted to keep the same cold value though.

https://www.mouser.ca/ProductDetail/Amphenol-Advanced-Sensors/CL-190/?qs=oS5/4SvoscEBAoSaABbyJQ==

 

[jasonv]

in that case. cl-190 is original spec. but cl-90 would be a better fit because of better resistance.

 

[rayma]

would you recommend replacing it or just soldering it back on? i cant find original mcintosh thermistor online.

No, you need a new one, the old one is defective, and there is no "McIntosh" brand part. Buy the CL-190
like McIntosh does. I would not second guess McIntosh about which spec of thermistor to buy.