HP 6632A  fan replacement and front panel posts - Page 1
Forum section: electronics / testgear

author: mtdoc
author_rank: Super Contributor
timestamp: June 11, 2013, 07:07:51 pm
content: In my newbieness I'm putting together a lab and got a HP 6632A powersupply/load from fleabay a while back. As others have noted the fans are loud. So I replaced it withTHIStemperature controlled fan for $10 on newegg.Quiet now! Even when drawing full power the fan is barely audible. My lab bench is in a walkout basement utility room where the ambient temp is usually in the mid 60s F - so I doubt this fan will ever need to crank up to full speed.I also put in some front side binding posts which turned out to be pretty easy to do. There were premade holes in the plastic on the back side of the front panel with output tabs avaiable on the PCB next to them. All I had to do was drill through the metal front plate. Used 12 awg silicon wire for the connection.

author: Dave
author_rank: Super Contributor
timestamp: June 11, 2013, 07:54:09 pm
content: I suggest you grab your air compressor and go berserk on that heatsink with a duster attachment. I cleaned my 6632B (bought off eBay) that way, and you wouldn't believe how much fine dust came out the other side.

author: mtdoc
author_rank: Super Contributor
timestamp: June 11, 2013, 11:47:18 pm
content: Quote from: Dave on June 11, 2013, 07:54:09 pmThanks. I already did that. Yes, lots of "cough, cough" dust....

author: bingo600
author_rank: Super Contributor
timestamp: June 12, 2013, 11:45:33 am
content: Where did you get the front posts from ?They look HP alike/BingoWho just discovered that those fan's can't be bought in EUMeaning i have to get them for $10 + $10 in shipping from US.And the stupid DK customs rules says i have to get the two i need in two different shipments ($12 goods value limit), else i have to pay $35 in VAT on top.

author: mtdoc
author_rank: Super Contributor
timestamp: June 12, 2013, 06:16:09 pm
content: Quote from: bingo600 on June 12, 2013, 11:45:33 amRadio ShackLINK-Who'd a thunk ?

author: grenert
author_rank: Frequent Contributor
timestamp: June 16, 2013, 01:30:21 pm
content: I've been favorably impressed with those Radio Shack binding posts. They seem to be really durable, without brittleness, and as said, they mimic the original HP ones very closeley. Interestingly, I noticed that some packages of these plugs are made in the UK!! Wonder who the OEM is?

author: Andy Watson
author_rank: Super Contributor
timestamp: August 06, 2013, 08:49:04 pm
content: Quote from: bingo600 on June 12, 2013, 11:45:33 amJust noticedhttp://www.rapidonline.com/their product numbers 17-3270 and 17-3271. Looks very similar to the HP part.

author: george graves
author_rank: Super Contributor
timestamp: June 23, 2014, 05:27:40 am
content: Interesting temp controlled fan. But isn't that fan blowing air *into* the heat sink, and getting it's air from outside (more of less)Looks like the fan's sensor in built into it, so how does it know when it needs to ramp up?

author: AlfBaz
author_rank: Super Contributor
timestamp: June 23, 2014, 09:18:56 am
content: Quote from: george graves on June 23, 2014, 05:27:40 amShame the one photo I was interested in is over-exposed. that being said isn't the yellow wire possibly the temperature sensor?

author: george graves
author_rank: Super Contributor
timestamp: June 23, 2014, 09:39:18 am
content: I think the yellow wire is for PC type motherboard RMP detection.

author: Andy Watson
author_rank: Super Contributor
timestamp: June 23, 2014, 09:46:13 am
content: Quote from: george graves on June 23, 2014, 05:27:40 amYes, the fan does blow into the heatsink. I don't know how the OP has wired his new fan, but manual has this to say about the fan control.Quote

author: mzzj
author_rank: Super Contributor
timestamp: June 23, 2014, 10:29:42 am
content: Quote from: mtdoc on June 11, 2013, 07:07:51 pmJust to be sure I would measure the heat sink temperature after 30 mins or so full load(max current to short-circuit).6632A/B has rather special output stage resulting in massive idle losses and even worse full-load losses.

author: nctnico
author_rank: Super Contributor
timestamp: June 23, 2014, 11:29:20 am
content: I agree. Mounting a fan which doesn't provide the designed airflow is asking for trouble. OTOH HP power supplies usually have temperature protection which kicks in soon enough.

author: macboy
author_rank: Super Contributor
timestamp: June 23, 2014, 12:34:08 pm
content: A temperature controlled fan is only effective when it is subject to the hot air that it is meant to exhaust. In your case, the fan is operating as an intake fan for the heatsink (it pushes air into the heatsink). It should be pulling hot air out, not pushing cold air in. Otherwise, it is operating based on the ambient (cold side) air temperature, not the hot side temperature.

author: mtdoc
author_rank: Super Contributor
timestamp: June 23, 2014, 12:59:33 pm
content: We'll, I'm in Montana right now and about 1000 mi from my lab so I won't be able to check until next week, but I sure thought I had mounted it to produce air flow in the same direction as the original. It sure doesn't look that way in the pics, does it!I may have reversed it after I took that pic. I honestly don't remember - it was quite a while ago.The yellow wire has nothing to do with the temp control. IIRC, the fan has a thermistor mounted near it's center on the intake side. Since you can't see it in the pic it makes me think the fan might actually be pulling air out of the heat sink as pictured despite the orientation of the blades.I can say that it's worked fine since the install including when used as an electronic load. But as I said earlier the ambient temp in my lab is usually on the cool side so maybe I've been lucky.I'll investigate more next week.

author: macboy
author_rank: Super Contributor
timestamp: June 23, 2014, 01:10:28 pm
content: Quote from: mtdoc on June 23, 2014, 12:59:33 pmIt looks like you mounted it the same way as the original, blowing air into the heatsink (and out the back of the unit I assume). That is the way the original fan was designed to work, but it wasn't a temperature controlled one. My point was that you can't really use the temperature controlled fan in this application, because the fan is on the cold side, not the hot side. If you could pull the thermistor out, and extend it to the hot side with a pair of wires, then it might work well.

author: mtdoc
author_rank: Super Contributor
timestamp: June 23, 2014, 01:23:06 pm
content: Quote from: macboy on June 23, 2014, 01:10:28 pmThat may be. As I think about it more I do recall pondering that issue a year ago when I did this. I do remember testing the temp response of the fan with a hot air gun.I can say that the fan speed does vary depending on the load and the unit has been working flawlessly.Lying in a tent, typing this on my phone whose battery is about to die...