HP 3312A function generator maintenance - Page 1
Forum section: electronics / repair

author: dimkasta
author_rank: Regular Contributor
timestamp: February 10, 2017, 02:11:45 pm
content: A few years back I bought a used HP3312AI use it mostly on audio frequencies and have no serious problems with it.However, the setting knobs are a bit jumpy, so I thought I should do some maintenance work on it.I have located the service manualhttp://literature.cdn.keysight.com/litweb/pdf/03312-90004.pdf?id=734381I was thinking to try and clean the pots and check any electrolytic caps for aging problems.Any advice on how I should approach this? Any other things I should check for?Thanks in advance

author: wn1fju
author_rank: Frequent Contributor
timestamp: February 10, 2017, 05:35:43 pm
content: Sounds like you are on the right track. Always consider mechanical issues before electrical. That is, a careful cleaning/lubrication of all the pots and pushbuttonswitches often cures all ills. I wouldn't think faulty electrolytics would cause your issues as they are probably mostly used in the power supply and faulty oneswould either render the unit completely dysfunctional or cause some massive distortion on your output. Start with alcohol or a mild cleaner like the Caig Deoxitproducts. Don't expect the unit to work right away after cleaning - it usually takes an hour or two for all the cleaning fluid to dry up.

author: dimkasta
author_rank: Regular Contributor
timestamp: February 10, 2017, 10:38:46 pm
content: You got to love engineering that looks nice, tidy and squeeky clean 30 years later

author: banzas
author_rank: Newbie
timestamp: June 30, 2021, 03:59:33 pm
content: Hi,I have been experience some offset problems, any thoughts?

author: wn1fju
author_rank: Frequent Contributor
timestamp: June 30, 2021, 11:31:20 pm
content: You would probably get more people to respond to you if you described the specific problem. Just saying "offset problem" doesn't tell us anything.However, 1) check the positive and negative power supplies, 2) check the offset control potentiometer, 3) check for any loose or disconnected wiring, 4) check the op-amp that the offset control uses to inject the offset voltage, and 5) check the output transistors.You will need to download a service manual of course.

author: Chris56000
author_rank: Frequent Contributor
timestamp: July 01, 2021, 08:38:31 pm
content: Hi!QuoteHave you seen the one that is available?It's so bloody furry and appallingly badly scanned that it's impossible to read anything on the circuit diagrams!It's so bad that I'm going to use a page of this as an example of a badly copied manual in the last chapters of my T & M Theory and Repair Book!Chris Williams

author: wn1fju
author_rank: Frequent Contributor
timestamp: July 01, 2021, 08:51:09 pm
content: To Chris56000:Yes, the free service manual download leaves much to be desired.I got mine from Artek Manuals ($7.50US for electronic download). It is perfectly fine.However, be warned that at some date, HP redesigned the A2 board on the 3312A. Apparently, a schematic of the newer board may be unobtainable. There were some forum posts about this a while ago and I don't remember the final outcome.