Scored Free HP 3455A, has issues to say the least - Page 1
Forum section: electronics / testgear

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: December 15, 2015, 04:53:05 pm
content: Last night I sold some vintage 70's Infinity speakers and picked up some vintage radio work for a guy that works for Dolby now and use to go on the road with Bonnie Rate and The Beach Boys. Really cool guy but in my opinion he gets ripped on his audio test equipment! For example he was just gonna give me the meter and an old HP 50hkhz scope. So I brought my laptop sig gen to test the scope and it died. He pulled a little plastic box out which was an audio tone generator and told me it cost him $1000 bucks, holy shit! A dds or VCXO and some knobs with a micro is 30 bucks at the most!!Anyways when I turn the meter on it just wigs out but I think all the buttons need a through cleaning! If there is more wrong with it than that is it worth the effort to fix? Any common problems with these guys? I have a 5.0000v ref but theres no way I can get a full six digit calibration on the thing at home... what would be the least expensive option to get a cal done? I checked on e-bay and in good working calibrated condition these are 700 bucks! Right now Im in a struggling position only doing consulting while I am primary parent to my 18 month old daugther so money and time are both valuable resources. I guess im wondering at what point do I scrap it with a heat gone or sell broken on e-bay?

author: macboy
author_rank: Super Contributor
timestamp: December 15, 2015, 05:16:56 pm
content: 3445A 3.5 digit Nixie tube voltmeter? Or did you get the model number wrong? Maybe 3456A? Old HP service manuals are frequently available for download, sometimes directly from Keysight, sometimes from elsewhere. Try to find it.Check the power rails first, for DC level and AC ripple. Many failures are due to power supplies. The point at which you put down your multimeter or soldering iron and pick up a big hammer is up to you.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: December 15, 2015, 08:14:36 pm
content: Im sorry 3455A no nixie tubes, 6 digit meter I believe. The truth is I could use a 6 digit meter but this thing is a lot more bulky than I wanted lol. If it is an easy fix than I am all for it but I dont want to spend days trouble shooting the thing I guess. Id rather sell it as is and by a 40,000cnt meter if it will be a PITA. Im thinking about fixing it up and selling it anyway just because I cant afford to CAL the thing most likely

author: nidlaX
author_rank: Frequent Contributor
timestamp: December 15, 2015, 08:24:12 pm
content: Quote from: rwgast_lowlevellogicdesin on December 15, 2015, 08:14:36 pmThose eBay prices are hugely inflated. I wouldn't expect to get more than $100 + shipping for one in working condition. That is considering what the 3456As and 3457As sell for.

author: TAMHAN
author_rank: Frequent Contributor
timestamp: December 15, 2015, 10:02:57 pm
content: Hello,why bother with Cal? If you work only for yourself (and/or a batch of clients who dont give a rats fart about calibration to NIST), I would suggest my approach.Whichever device currently is the most accurate in your lab, is considered the "standard". All other units are then calibrated against it.Voltnutters can now beat me, but I am well on the way to a 10k process computer order with this setup...

author: lowimpedance
author_rank: Super Contributor
timestamp: December 15, 2015, 11:43:40 pm
content: "Wigs out" in what way??, random display, all ------- etc . Without looking into the service manual I would suggest the problem is most likely in the power supply area.The switches of this era HP always have 'that clicky feel' so I would not be looking there straight up first (unless they are visually dirty).some linkshttps://www.eevblog.com/forum/testgear/hp-3455a-teardown/http://bama.edebris.com/manuals/hp/3455a/

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: December 16, 2015, 12:13:25 am
content: Ya the display just shows a bunch of random stuf - voltages positive voltages all over the place. The buttons do no seem to make any difference when I press them but they feel weird like they all need a good cleaning and maybe a bunch are stuck down, that is my first thought abut why it is going nuts. Fan works powers on seems ok. I dont have a ton of time to put in to it right now havent even opened it up yet. See I only have a 5.0000v reference and im not sure I will even be able to cal all the ranges based on that. Will boosting that voltage with opamps do the job for higher ranges or will the opamp cause instability issues?Basically I just want to use it for higher end ADC work, i.e maybe a 24bit ADC with a 1 volt reference or maybe a 30 volt reference who knows... but that is really the biggest use I can see for this thing and it is HUGE.

author: Vgkid
author_rank: Super Contributor
timestamp: December 16, 2015, 12:37:46 am
content: Download the manual, then run the self test. If it is like the 3456A the failing psu will cause a bunch of errors.

author: cncjerry
author_rank: Unknown
timestamp: December 16, 2015, 09:42:00 am
content: I've repaired a bunch of the meters. The buttons can't really be fixed unless there is soda or something in them, which is unlikely. Many 3455a meters have sticky buttons but still function correctly. If it powers on without a self test code, then most likely the meter is functional. Many of the units I've repaired hang at power on with just a few buttons lit up or all ranges display as OL. Having one that at least tries to display a number is a great start. I've contributed a number of repairs to a thread a while back. Search on 3455a in the repair forum.I have 4 or 5 functional 3455a meters. I have a black face one I use often. They are great old meters and I find them easy to repair if you have more than one as you can split them internally. Even a calibrated 3455a is only worth about $175, max, in good shape, because the odds of it holding cal is low as these meters are getting old and prone to failure.I buy broken ones for around $40 plus shipping, usually like $20, and treat them as a puzzle to pass the time. The 3456a is a great, stable meter for its age. I love the large, bright, red displays on them.Post a picture of your meter operating.