Posted by Thrint [ 205.188.116.67 ] on September 05, 2005 at 09:47:24:

In Reply to: Fisher 500C-how hot is too hot? posted by hurdy_gurdyman on September 04, 2005 at 08:22:40:

a 7591 running at +400 is going to pull less than 70 mA before developing plate glow. So, what is creating the heat? I-squared-R in the primary winding? What is primary DCR? Do the calculation, and measure idle current.

Is there any other source of heat? you mentioned the rectifier a bit ago.

Have you actually measured temp? 8 seconds is a long time when holding your paws to heat. There is a diff between hot and inducing damage, and hot and able to burn fingers. 85-C is not going to allow 8 seconds of good finger contact, I can assure you...

Still, none of my OPTx's run hotter than I can stand, so I would urge you to discover the heat source.

There is *NO* magic involved, so examine it thoroughly.
cheers,
Douglas

Replies:

• Re: that's power iron hot... - hurdy_gurdyman 10:38:28 09/05/05 (0)