Re: [time-nuts] HP 5372A Fan
At 12:44 AM 3/10/2010, Ed Palmer wrote... It would seem to make more sense to have the fan blowing hot air out the back and drawing the hot inside air over the temperature sensor. The reason to have a fan blow in is so you can put a filter on it. It also creates more turbulence inside the box, for more effective heat removal. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A Fan
Good point about the filter, but it doesn't appear that the 5371a or 5372a ever had a filter. Unless it was just done out of habit because other HP units did have a filter. Ed Mike S wrote: At 12:44 AM 3/10/2010, Ed Palmer wrote... It would seem to make more sense to have the fan blowing hot air out the back and drawing the hot inside air over the temperature sensor. The reason to have a fan blow in is so you can put a filter on it. It also creates more turbulence inside the box, for more effective heat removal. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A Fan
Mike S wrote: At 12:44 AM 3/10/2010, Ed Palmer wrote... It would seem to make more sense to have the fan blowing hot air out the back and drawing the hot inside air over the temperature sensor. The reason to have a fan blow in is so you can put a filter on it. It also creates more turbulence inside the box, for more effective heat removal. You want to collect dust before it comes into the electronics, yes. I have never had a problem with hot air blowing at me in front of a HP5372A, and I have spent many ours in front of one. The HP5372A has many good places for venting air, even if the air-tunnel effect is far from optimum, but kind of typical for its age. I have yet not found an instrument that fully replaces it either even if several outperform it in resolution (200 ps) and memory-depth (8192 time-stamps can be stored). Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A Fan
Ed Palmer wrote: Good point about the filter, but it doesn't appear that the 5371a or 5372a ever had a filter. Unless it was just done out of habit because other HP units did have a filter. If you want to toss a filter on it because your environment isn't exactly clean, it is trivial. Maybe that is part of their rational. I am by no means a fan and air-flow expert, but I seem to recall something about it being easier to push air into a box than pulling it out of it. Higher pressure air should also have a slightly higher ability to remove heat (more molecules to heat), but I guess heating-gurus can tell me it is of marginal effect. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A Fan
Ed, From your description of the fan noise, I have one concern. If the fan speed seems to increase without a good cleaning or change in the supply voltage, then it's likely that the airflow has been decreased, an obvious speed up is not good news. Pete Rawson On Mar 9, 2010, at 10:44 PM, Ed Palmer wrote: I have a question for owners of the HP 5372A (and probably 5371A) Time Interval Analyzer. Is the fan on the back blowing out or sucking in? I was looking at mine to see about replacing the fan with a quieter one and I was surprised to see that mine is sucking in. This doesn't make sense to me for two reasons: 1. It blows hot air out the front and bottom straight at the operator. Uncomfortable on a hot day. 2. Just inside the unit at the back on the motherboard there's a temperature sensor that controls the fan speed. Why would you blow cool outside air over the temperature sensor? It would seem to make more sense to have the fan blowing hot air out the back and drawing the hot inside air over the temperature sensor. I experimented with this configuration and found that the noise level went up because the fan was turning faster - no big surprise there. I can't find any info in the manual (service or operating) about this. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A Fan
Yes, the fan is variable speed and it's 12V DC. It's described in the motherboard section of the service manual on page 11-4 (pdf page 503). That's why I thought it was so odd that the fan is blowing cool outside air over the thermal sensor on the motherboard. I guess they could have calibrated the system to work on the basis of ambient temperature variations, but it seems backwards to me. Ed Mark Sims wrote: Are you sure that it has a variable speed fan? My 5372A has a pretty quiet fan and I have never tried to change it. I am assuming that it uses the same 117V fan as the 5371A. That thermal switch may be a power supply shutdown. I have a couple of 5371A's that are a different matter. Utterly obnoxious fans. I put in much quieter 12V fans. I powered them with a separate wall wart module mounted inside the box with velcro. I used Nidec Beta V TA450DC fans rated at 250 mA. Again, I checked the before/after thermal environment and found no changes. I have some even quieter NMB Smartfans with a thermal sensor. They draw around 150 mA until the temp reaches 35C, then they kick in at 750 mA and scream bloody murder. _ Hotmail: Trusted email with powerful SPAM protection. http://clk.atdmt.com/GBL/go/201469227/direct/01/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
