Hello Bob and Patrick,
Of course, what I really should have asked is if I should be worried about the internal temperature because the fan seems to run at full speed all the time and still there's no obvious airflow (detectable outside), although there's no obstruction. I have measured the voltage at the red feedthrough capacitor as around 12VDC.
From your comments, I tend to conclude that there's no need to worry. While calibrating the 'scope a few weeks ago, I had an external fan blowing air over the hybrids in very low volume at a very low speed, hardly more than a draft. It was enough to keep all hybrids almost as cool as the environment, whereas e.g. U600 heats up to at least 50C (untouchable) in still air. So, together with your comments, I've answered my own question I guess.
Thanks again for your input!
Raymond
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--- In TekScopes@..., "Patrick Wong" <patwong3@...> wrote:
Hi Raymond,
I own a 2465A and 2467. At least with those models, there is only one fan speed as there is no thermostatic control. I do not think the fans are very noisy and the amount of air flow is not tremendous.
I suggest that you remove the rear plastic cover and measure the voltage from the feedthrough capacitor located in the upper left corner (when viewing the rear) to ground. Note that the fan receives DC power via that capacitor.
You should find this voltage is constant. If you agree that the voltage is constant, yet the fan speed varies, then the fan needs help (perhaps cleaning) or replacement.
Good luck,
Patrick Wong AK6C
--- In TekScopes@..., "raymonddompfrank" <r.domp.frank@> wrote:
Hi,
The following has been sort of haunting me for a while:
When I switch on my 2445B, the fan starts running at a low speed and is barely
audible. After a while, it increases its speed to what I consider its maximum.
It is quite audible by then.
