Ebay HP function generator 3314A - Page 1
Forum section: electronics / testgear

author: Applemac
author_rank: Regular Contributor
timestamp: January 03, 2019, 09:14:27 pm
content: Hi just received an HP 3314A functiong generator off of ebay. Opened it up before plugging inlook ok apart fron some dust. Went through self calibration fine looks ok. Anyway after turning the unit off to answer the door, the mains electric tripped and smoke was coming out of the unit. Took the plug out of the back of the unit left it a while, plugged it back in turn on went through calibration fine. No smoke that I could see. So turned it off, cant see any burn marks or smoke patches but there is a lingering pungent smell. Is this possibility the old dust or would this be something more serious?

author: Kean
author_rank: Unknown
timestamp: January 03, 2019, 09:47:39 pm
content: Very likely the smoke came from the aging capacitors in the AC input filter. Seen this happen many times on older test gear.See left side of schematic on page 205 of 1983 service manual available on Keysight website athttps://www.keysight.com/en/pd-3314A%3Aepsg%3Apro-pn-3314A/programmable-function-generator

author: lowimpedance
author_rank: Super Contributor
timestamp: January 04, 2019, 09:51:21 am
content: As Kean said ,the mains emi filter has flamed out. Many Post's here relating to this, search RIFA caps.Usually after the smoking event the offending component goes open cct and the gear goes on working.Find the cap remove then clean up and replace.

author: Kean
author_rank: Unknown
timestamp: January 04, 2019, 11:19:00 am
content: The failed filter cap is most likely an integral part of the mains input socket (based on schematic). if you pull it out for visual inspection, you can often see a skid mark where the smoke escaped.It is a good idea to replace it if you want to return the unit to original specifications, and more importantly try to get rid of the smell. The hassle is finding a physically identical replacement - some are very specific models that are obsolete.

author: Applemac
author_rank: Regular Contributor
timestamp: January 04, 2019, 08:15:11 pm
content: Funny thing is the unit is functioning it calibrates fine. Im going to give it a good cleaning as there is a lot of dust inside could of been this burning then im going to check the caps as advised thanks all for the helpful info it’s appreciated

author: Applemac
author_rank: Regular Contributor
timestamp: January 04, 2019, 08:32:57 pm
content: Hi you say page 205 if the manual i hv an orginal manaul theres no page 205 its split inti sections 8.69 ect do u know which section?

author: Kean
author_rank: Unknown
timestamp: January 05, 2019, 12:45:15 pm
content: Quote from: Applemac on January 04, 2019, 08:32:57 pmI only saw the schematics in the 1983 version of the service manual available for download at the web page I linked above, as I don't have the paper manual.See Part Number: 03314-90021 (Apr83) - pages 205 & 206 of the downloaded PDF is labelled as Fig 8-31 Power Supplies, and it also shows "8-69/8-70".That PDF may not be the correct service manual for your unit, but I guess is likely the same section "8.69" that you refer to from your manual.These mains input sockets are usually a metal sealed & potted box including the EMI filter components (inductors and capacitors), so they are not easy to repair.They come in various shapes and sizes. Google for "iec main input emi filter" and take a look at the associated images.