HP53131 fan always on? - Page 1
Forum section: electronics / testgear

author: S57UUU
author_rank: Regular Contributor
timestamp: December 01, 2023, 03:57:57 pm
content: Bought this counter, no oven options. As soon as I plug in the mains cable, the fan runs, regardless of the power button state. Is this the normal behavior for this counter? My lab is also a bedroom, so this is a bit annoying!

author: TheSteve
author_rank: Unknown
timestamp: December 01, 2023, 04:07:25 pm
content: Yes it is normal. If you have the high stability version it will keep the oven going at all times. There have been mods posted to change the power switch to a hard on/off.

author: Hexley
author_rank: Regular Contributor
timestamp: December 01, 2023, 05:37:55 pm
content: There is an interesting project that allows the front panel power switch of the 53131A to control the mains power through a small relay that can be mounted inside the instrument. Seehttps://sites.google.com/site/wayneholder/hp-53131a-power-off-mod.The key part is an adapter board that can be ordered from OSH Park, which breaks out the power switch signals. That board is still available, as I ordered one last year to implement this system in my own 53131A.I have attached a picture of the other part of the mod -- the relay board -- installed in the counter in case you are interested in knowing how it looks.

author: S57UUU
author_rank: Regular Contributor
timestamp: December 02, 2023, 05:33:27 am
content: Thanks for the info. I think I'll just install one of those "inline switches" (as used on small lamps) on the power cord. When I'll need high accuracy, I will just use a rubidium or a GPSDO.

author: artag
author_rank: Super Contributor
timestamp: December 02, 2023, 05:16:11 pm
content: I'm fussy about fan noise and I can't generally hear it. It could be that it's got old and a bit noisy.

author: S57UUU
author_rank: Regular Contributor
timestamp: December 03, 2023, 06:07:56 am
content: Yes, it's a HP, so it has more than 20 years on its back, might try a drop of oil.

author: kj7e
author_rank: Frequent Contributor
timestamp: December 04, 2023, 12:26:53 am
content: Ive replaced the old stock fan with Sunon HA40201V4, which are very quiet. I can hardly hear my 53132a in standby when I'm next to it.https://www.digikey.com/en/products/detail/sunon-fans/HA40201V4-1000U-A99/6198729

author: S57UUU
author_rank: Regular Contributor
timestamp: December 04, 2023, 02:57:52 pm
content: Looks nice, including the price. I'll probably go for it, thanks.

author: alan.bain
author_rank: Regular Contributor
timestamp: February 25, 2024, 04:02:45 pm
content: My HP53132 has a non functional fan. Have bought a Sunon MF40201V2-1000U-A99 which fits perfectly, but realise I don't know which way round it is meant to be. Can anyone help i.e. does it suck air into the case or blow it out?(It has the most useless timebase for a 12 digit counter - atiny TCXO which makes me wonder why the supply and fan are always on to keep a rubbish timebase stable....). I realise there were other options available...Alan

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 26, 2024, 01:52:54 pm
content: In my units the fan blows out.I also used four of these 'F-331-C8012' rubber fan mounts to quieten the fan even more to good effect. (I cut the extra length off them once I had it all installed, you'll see what I mean).https://www.digikey.jp/short/c29vmwp4On the topic of the crappy standard time base, I think the intention was for the purchaser to either option in one of the 3 OCXO options, or use an external reference if not.The included standard time base was just enough to run the unit and get a frequency reading, as unstable as it is...

author: alan.bain
author_rank: Regular Contributor
timestamp: February 28, 2024, 09:05:54 pm
content: Thanks to above mine now has been replaced, blowing out and is so much quieter.I have wondered about adding a better timebase - there seem to be PCBs for doing this out there which look very like the schematic in the CLIP. It would also be nice to add an input C, for now though I can reach for the HP5342A for that.

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 28, 2024, 11:27:43 pm
content: I have just finished the design of my own version of the optional input C board.If you are able to solder SMD parts, I can send you a kit of parts for what they're worth plus postage.

author: Tony_G
author_rank: Super Contributor
timestamp: February 28, 2024, 11:40:40 pm
content: Hey TERRA,Did you post about the Input C project anywhere? I took a quick web search and didn't find a post on the forum - I'm just interested to see what you did as my 53131A came with an original board from HP.Thanks,TonyG

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 29, 2024, 06:32:54 am
content: I have a thread on the HP groups.io site. I haven't made a post here or anywhere else yet.https://groups.io/g/HP-Agilent-Keysight-equipment/topic/101797284#142109I also put the design files up here:https://www.pcbway.com/project/shareproject/HP_53131A_53132A_53131A_3GHz_Input_Option_030_e0266e59.html