DH+ resistor temperature

Hi,

I’ve been doing some tests with a new PC based oscilloscope on DH+, just getting my settings right etc. To facilitate this I strung 1mtr of blue hose cable between 2 racks running on my table. Set my scope up ok, but i then noticed the termination resistors were really hot.

I’d used a 150ohm 1/2W resistor at each end.

Tried measuring the temperature On my fluke, and it got up to 70deg C.

Is this normal? I’m not one for going round feeling resistors - but I thought these were a bit hot....

Andy

No, not normal at all. Recommend disconnect and determine the cause. Those resistors should run at ambient temperature.

Thanks for the help. I’ve done some more testing.

The resistors that we’re running at 70degC we’re blue bodied ones.

I’ve done the same test again, but I’ve dug out some old resistors that were on some salvaged PLCs. One has a dark brown body, the other beige. Both are 150 ohm.

The brown resistor runs at 43 degC
The beige resistor runs at 45 degC

Looking at this it seems the brown resistors are a better option. Unless the blue ones I’ve got are not good quality.


Andy