HP 3457a issues - Page 1
Forum section: electronics / testgear

author: Rick
author_rank: Frequent Contributor
timestamp: July 19, 2013, 10:02:17 pm
content: I have a broken 3457a which blows the line fuse when I turn it on. I am suspecting the primary of the transformer is shorted. I measure only 15 ohms with a multimeter. Is it normal? Does anybody have the specs of that transformer? When I got it there was a 1A line fuse inside, whereas it should have been a 200 mA fuse. Also it must have undergone a physical shock because there is a big dent on its metal cover (the transformer's cover) in one corner.Thank you.

author: Wim13
author_rank: Frequent Contributor
timestamp: July 20, 2013, 05:17:52 pm
content: Did you check this post from some time ago...https://www.eevblog.com/forum/testgear/just-got-3457a-and-then-boom/

author: Rick
author_rank: Frequent Contributor
timestamp: July 20, 2013, 05:33:02 pm
content: Yes I have read it some time ago and that came to my mind too but I shall look into it in detail. Thank you. The unit is very clean. No damage sign at all especially around the line filter. Actually I checked again my Schaeffner filter has the same type of bulge that "Bingo600" had. I shall replace it anyway.+But I think the line filter is still ok. I removed the connectors and measured the line voltage behind it, I get a reading of 230V.On the other hand the plastic cover of the transformer on the side where there are cables, seems to have overheated.

author: Rick
author_rank: Frequent Contributor
timestamp: September 08, 2013, 10:31:01 pm
content: Update on this topic: the transformer is shorted. It blows the fuse with everything disconnected. I knew that from the beginning but now it is confirmed. I shall get a new one wound by a local company and see if it works. Hopefully it will. Thanks a lot for all your help

author: Rick
author_rank: Frequent Contributor
timestamp: October 07, 2013, 11:43:05 pm
content: I have a new transformer and here is the video of the self test of the unit:It passes self-test but beeps a lot.Any idea why that may happen?

author: nanofrog
author_rank: Super Contributor
timestamp: October 07, 2013, 11:56:02 pm
content: Lost CAL data perhaps.

author: Rick
author_rank: Frequent Contributor
timestamp: October 18, 2013, 08:11:58 pm
content: Quote from: nanofrog on October 07, 2013, 11:56:02 pmWhen I try to run Auto calibration I get the following message : "9 not calibrated"If a unit loses its calibration data, does it still measure something, although the values would be wrong (like it is the case here) or it does not measure anything at all ?I may have placed the main controller card on a metal surfaceand when I measured the voltage across the battery it was recovering from 2.9x Volt to 3.0x V. Self test is still ok.With the ground connection established I still hear lots of beeps...

author: AlfBaz
author_rank: Super Contributor
timestamp: October 18, 2013, 10:36:06 pm
content: after the self test the annunciator above the error marker on the LCD is flashing. Press shift then error and see what it says. There are also a bunch of registers you can read which can give you extra diagnostics. Its all in the easily available user and service manuals

author: AlfBaz
author_rank: Super Contributor
timestamp: October 18, 2013, 10:40:31 pm
content: To check if you have lost all call data you may try the "CALNUM?" option. It indicates how many times the unit has been fully cal'd.Press BlueButton then C (Offset Comp) then the down arrow then enter

author: nanofrog
author_rank: Super Contributor
timestamp: October 18, 2013, 11:49:11 pm
content: I'm used to the unit still working once the codes have been cleared (via some combination of keystrokes). Check the manual, and see what the procedure is.BTW, if you don't have one, here's BAMA's page for the HP3457a (http://bama.edebris.com/manuals/hp/3457a/). The Service Manual has even been uploaded.

author: Rick
author_rank: Frequent Contributor
timestamp: October 19, 2013, 01:18:27 am
content: Quote from: AlfBaz on October 18, 2013, 10:36:06 pmRight I missed that. Thanks. I definitely need to go through the service manual.

author: Rick
author_rank: Frequent Contributor
timestamp: October 19, 2013, 01:19:42 am
content: Quote from: AlfBaz on October 18, 2013, 10:40:31 pmI remember having checked that when it first powered on. I think it must have been calibrated "14000" times or something.

author: Rick
author_rank: Frequent Contributor
timestamp: October 19, 2013, 01:20:34 am
content: Quote from: nanofrog on October 18, 2013, 11:49:11 pmYeah I downloaded all of them (user and service manuals). Time to readThanks.

author: AlfBaz
author_rank: Super Contributor
timestamp: October 19, 2013, 01:31:22 am
content: Quote from: Rick on October 19, 2013, 01:19:42 amhmm that seems like a very unlikely number