"Leland C. Scott" wrote in message
...
Thanks again for the info.

Exactly the same thing happened to me. It's fortunate I found a
service manual for my frequency counter on eBay or I might never
have diagnosed the problem. The manual states that the normal
operating temperature for the oscillator is 80-84C. I bought new
thermal fuses from Digi-Key. Investigating the properties of these
devices I found that the exact temperature at which they open isn't
a simple thing to determine. To be safe but avoid the fuse opening
again under normal conditions, I selected a Panasonic "N124" type
rated at 130C. The Digi-Key catalog number is P10922-ND. This
turned out to be a bit larger than the original part. I suggest
you try the smaller "F130" part, catalog number P10913-ND. Just
to be safe, of course, verify these part numbers before ordering.

Taking apart the oscillator is a bit nerve-wracking if you don't
know what to expect, but the fuse replacement isn't at all hard
to do.

Have fun.

-Henry